================================================================================ /***************************** MISSION TEMPLATE *******************************/ /* Template: Mission Template Rev: 1993-09-24 */ /* Note: Complete one template for each mission or campaign. Identify */ /* multiple hosts associated with the mission by repeating the */ /* lines beginning and ending with the MISSION_HOST values. For */ /* each instrument_host identified, repeat the 3 lines for the */ /* MISSION_TARGET object for each target associated with the host. */ /* Also complete a separate REFERENCE template for each new */ /* reference submitted to PDS. */ /* Hierarchy: MISSION */ /* MISSION_INFORMATION */ /* MISSION_HOST */ /* MISSION_TARGET */ /* MISSION_REFERENCE_INFORMATION */ /* MODIFICATIONS: */ /* 95-JUL-27 RMONARREZ */ /* Combined P12 and PVO into one template */ OBJECT = MISSION MISSION_NAME = "PIONEER VENUS" OBJECT = MSNINFO MISSION_START_DATE = 1968-06-01 MISSION_STOP_DATE = 1992-10-07 MISSION_ALIAS_NAME = "P12" MISSION_DESC = " Mission Overview ================ Pioneer Venus consists of two basic spacecraft: Orbiter and Multiprobe [COLIN1977]. The latter was separated into five separate vehicles near Venus. These were the probe transporter (called the Bus), a large atmospheric entry probe (dubbed Sounder) and three identical smaller probes (called North, Day, and Night in accordance with their entry locations). At Venus all six spacecraft communicated directly back to the Earth-based Deep Space Network (DSN) and, in the case of the Multiprobe mission, to two special receiving sites near Guam and Santiago (Chile). The Orbiter was launched on May 20, 1978, encountered Venus on December 4, 1978, was inserted into orbit on that same day after a Type II interplanetary cruise trajectory lasting 198 days and covering more than 500 x 106 km. Twelve scientific experiments were included in the instrumentation payload and a few radioscience investigations were planned using the S-band telemetry signal carrier and a special X-band beacon included as part of the spacecraft hardware. Scientific observations were made both in-cruise and in-orbit. The nominal in-orbit mission was designed to extend for one Venus year (243 days). At the time this Special Issue was submitted for publication the nominal mission was complete and the Orbiter was continuing into an extended mission phase. It appears that sufficient fuel remains to permit full operation through calendar year 1980, at least. During the nominal mission all but two experiments operated 100 percent successfully. One, the Radar Mapper, produced unusable data for a 32-day period from December 18, 1978 to January 19, 1979. The data lost will be acquired during the extended Orbiter mission. The other, the Infrared Radiometer, failed to operate after February 14, 1979, but had collected and enormous quantity of valuable information prior to that date. The Multiprobe was launched on August 8, 1978, encountered Venus on December 9, 1978 (just five days following the Orbiter insertion) after a Type I interplanetary cruise trajectory lasting 123 days and covering 330 x 106 km. The Sounder was released from the Bus on November 15, 1978, and the three small probes were released simultaneously on November 19, 1978. All probes entered (200-km altitude) the Venus upper atmosphere within a time span of about 11 min and descended to the surface in a period from 53 to 56 min, all the time performing scientific observations. The Bus made a delayed (~90 min) entry relative to the probes into Venus' upper atmosphere and burned up at about 110-km altitude since it was not protected, as were the probes, with entry heat shields. Scientific observations were made during the one-minute interval from 700 to 110 km. Although not designed for `survival' after impact, the Day probe managed to transmit for over 67 min on the surface (it in fact continued to transmit after the Bus transmission ceased). Seven scientific experiments were included in the Sounder instrumentation payload, three identical experiments in each small probe, and two in the Bus. Again, radioscience experiments were performed using, separately or together, the S-band telemetry signal carriers emanating from the spacecraft and received at the Earth-based tracking stations. In general, all instruments performed nominally, although certain instruments behaved anomalously on all four probes near the surface. Mission Phases ============== The Pioneer Venus Orbiter (PVO) phases are presented followed by the Pioneer Venus Multiprobe (PVMP) phases. PIONEER VENUS ORBITER PRELAUNCH ------------------------------- The spacecraft was delivered to the launch site at Kennedy Space Center on March 14, 1978. Spacecraft Id : PVO Target Name : VENUS Mission Phase Start Time : 1968-06-01 Mission Phase Stop Time : 1978-05-20T13:13 Spacecraft Operations Type : ORBITER PIONEER VENUS ORBITER LAUNCH ---------------------------- The spacecraft was launched atop an Atlas-Centaur from Kennedy Space Center. Spacecraft Id : PVO Target Name : VENUS Mission Phase Start Time : 1978-05-20T13:13:0 Mission Phase Stop Time : 1978-05-21 Spacecraft Operations Type : ORBITER PIONEER VENUS ORBITER CRUISE ---------------------------- Two small trajectory correction maneuvers were made on June 1 and November 2, 1978. Interplanetary cruise scientific data were collected. The Pioneer Venus Orbiter completed its 300-million-mile voyage in 6+ months and was placed into Venusian orbit on December 4, 1978. Spacecraft Id : PVO Target Name : VENUS Mission Phase Start Time : 1978-05-21 Mission Phase Stop Time : 1978-12-04 Spacecraft Operations Type : ORBITER PIONEER VENUS ORBITER ORBITAL ----------------------------- The orbiter was placed into Venusian orbit on December 4, 1978, less than a week before the arrival of the Pioneer Venus Multiprobe. The planned mission ended August 4, 1979, and the extended mission began August 5, 1979. Two extended initiated on April 3, 1980, and December 2, 1980. Spacecraft Id : PVO Target Name : VENUS Mission Phase Start Time : 1978-12-04 Mission Phase Stop Time : 1992-10-02 Spacecraft Operations Type : ORBITER PIONEER VENUS MULTIPROBE LAUNCH ------------------------------- The spacecraft was launched atop an Atlas-Centaur from Kennedy Space Center. Spacecraft Id : PVMP Target Name : VENUS Mission Phase Start Time : 1978-08-08 Mission Phase Stop Time : 1978-08-08 Spacecraft Operations Type : ATMOSPHERIC PROBE PIONEER VENUS MULTIPROBE ENCOUNTER ---------------------------------- The Multiprobe encountered Venus on December 9, 1978 (just five days following the Orbiter insertion) after a Type I interplanetary cruise trajectory lasting 123 days and covering 330 x 106 km. The Sounder was released from the Bus on November 15, 1978, and the three small probes were released simultaneously on November 19, 1978. All probes entered (200-km altitude) the Venus upper atmosphere within a time span of about 11 min and descended to the surface in a period from 53 to 56 min, all the time performing scientific observations. The Bus made a delayed (~90 min) entry relative to the probes into Venus' upper atmosphere and burned up at about 110-km altitude since it was not protected, as were the probes, with entry heat shields. Scientific observations were made during the one-minute interval from 700 to 110 km. Although not designed for `survival' after impact, the Day probe managed to transmit for over 67 min on the surface (it in fact continued to transmit after the Bus transmission ceased). Seven scientific experiments were included in the Sounder instrumentation payload, three identical experiments in each small probe, and two in the Bus. Again, radioscience experiments were performed using, separately or together, the S-band telemetry signal carriers emanating from the spacecraft and received at the Earth-based tracking stations. In general, all instruments performed nominally, although certain instruments behaved anomalously on all four probes near the surface. Spacecraft Id : PVMP Target Name : VENUS Mission Phase Start Time : 1978-12-07 Mission Phase Stop Time : 1992-12-07 Spacecraft Operations Type : ATMOSPHERIC PROBE" MISSION_OBJECTIVES_SUMMARY = " Mission Objectives Summary ========================== The two Pioneer flights to Venus were intended to explore the atmosphere of the planet, to study its surface using radar, and to determine its global shape and internal density distribution. The Pioneer Venus Orbiter was designed to operate for 8 months or more making direct and remote sensing measurements. The Pioneer Venus Multiprobe spacecraft was designed to separate into 5 separate atmospheric entry craft some 12.9 million km (8 million miles) before reaching Venus. Each probe craft was designed to make measurements of the characteristics of the atmosphere from its highest regions to the surface of the planet in a period of a little more than 2 hours at points spread over the Earth-facing hemisphere of the planet." END_OBJECT = MSNINFO OBJECT = MSNHOST INSTRUMENT_HOST_ID = "PVO" OBJECT = MSNTARG TARGET_NAME = "VENUS" END_OBJECT = MSNTARG END_OBJECT = MSNHOST OBJECT = MSNREFINFO OBJECT = MSNREFINFO REFERENCE_KEY_ID = "COLIN1980B" END_OBJECT = MSNREFINFO END_OBJECT = MISSION /******************************************************************************/ /* Streamlined Instrument Host Template (combined Earthbase and Spacecraft) */ /******************************************************************************/ /* Template: Instrument Host Template Rev: 1993-09-24 */ /* Note: Complete one template for each instrument host. Identify each */ /* instrument host reference by repeating the 3 lines for the */ /* INSTRUMENT_HOST_REFERENCE_INFO object. Also complete a separate */ /* REFERENCE template for each new reference submitted to PDS. */ /* Hierarchy: INSTRUMENT_HOST */ /* INSTRUMENT_HOST_INFORMATION */ /* INSTRUMENT_HOST_REFERENCE_INFO */ OBJECT = INSTRUMENT_HOST INSTRUMENT_HOST_ID = PVMP OBJECT = INSTRUMENT_HOST_INFORMATION INSTRUMENT_HOST_NAME = "PIONEER VENUS MULITPROBE" INSTRUMENT_HOST_TYPE = "SPACECRAFT" INSTRUMENT_HOST_DESC = " Instrument Host Overview ======================== Mass: 290 kg (bus), 315 kg (large probe), 90 kg (each small probe) Power System: Solar Array of 241 W (bus), Batteries (probes) The Pioneer Venus Multiprobe consisted of a bus which carried one large and three small atmospheric probes. The large probe was released on November 16, 1978 and the three small probes on November 20. All four probes entered the Venus atmosphere on December 9, followed by the bus. The Pioneer Venus large probe was equipped with 7 science experiments, contained within a sealed spherical pressure vessel. This pressure vessel was encased in a nose cone and aft protective cover. After deceleration from initial atmospheric entry at about 11.5 km/s near the equator on the Venus night side, a parachute was deployed at 47 km altitude. The large probe was about 1.5 m in diameter and the pressure vessel itself was 73.2 cm in diameter. The science experiments were: * a neutral mass spectrometer to measure the atmospheric composition * a gas chromatograph to measure the atmospheric composition * a solar flux radiometer to measure solar flux penetration in the atmosphere * an infrared radiometer to measure distribution of infrared radiation * a cloud particle size spectrometer to measure particle size and shape * a nephelometer to search for cloud particles * temperature, pressure, and acceleration sensors The three small probes were identical to each other, 0.8 m in diameter. These probes also consisted of spherical pressure vessels surrounded by an aeroshell, but unlike the large probe, they had no parachutes and the aeroshells did not separate from the probe. Each small probe carried a nephelometer and temperature, pressure, and acceleration sensors, as well as a net flux radiometer experiment to map the distribution of sources and sinks of radiative energy in the atmosphere. The radio signals from all four probes were also used to characterize the winds, turbulence, and propagation in the atmosphere. The small probes were each targeted at different parts of the planet and were named accordingly. The North probe entered the atmosphere at about 60 degrees north latitude on the day side. The night probe entered on the night side. The day probe entered well into the day side, and was the only one of the four probes which continued to send radio signals back after impact, for over an hour. More detailed information on the probes is available. The Pioneer Venus bus also carried two experiments, a neutral mass spectrometer and an ion mass spectrometer to study the composition of the atmosphere. With no heat shield or parachute, the bus survived and made measurements only to about 110 km altitude before burning up. The bus was a 2.5 m diameter cylinder weighing 290 kg, and afforded us our only direct view of the upper Venus atmosphere, as the probes did not begin making direct measurements until they had decelerated lower in the atmosphere." END_OBJECT = INSTRUMENT_HOST_INFORMATION OBJECT = INSTRUMENT_HOST_REFERENCE_INFO REFERENCE_KEY_ID = "N/A" END_OBJECT = INSTRUMENT_HOST_REFERENCE_INFO END_OBJECT = INSTRUMENT_HOST /******************************************************************************/ /* Streamlined Instrument Host Template (combined Earthbase and Spacecraft) */ /******************************************************************************/ /* Template: Instrument Host Template Rev: 1993-09-24 */ /* Note: Complete one template for each instrument host. Identify each */ /* instrument host reference by repeating the 3 lines for the */ /* INSTRUMENT_HOST_REFERENCE_INFO object. Also complete a separate */ /* REFERENCE template for each new reference submitted to PDS. */ /* Hierarchy: INSTRUMENT_HOST */ /* INSTRUMENT_HOST_INFORMATION */ /* INSTRUMENT_HOST_REFERENCE_INFO */ OBJECT = INSTRUMENT_HOST INSTRUMENT_HOST_ID = PVO OBJECT = INSTRUMENT_HOST_INFORMATION INSTRUMENT_HOST_NAME = "PIONEER VENUS ORBITER" INSTRUMENT_HOST_TYPE = SPACECRAFT INSTRUMENT_HOST_DESC = " Instrument Host Overview ======================== The Pioneer Venus mission objectives dictated the requirement for two spacecraft designs designated the Orbiter and the Multiprobe. (The Multiprobe is defined as the Bus with the one Large Probe and three identical Small Probes attached in the launch/cruise configuration.) The conceptual designs of these spacecraft resulted from Phase B studies conducted from October 1972 to July 1973, and after selection of the spacecraft contractor, Hughes Aircraft Company, in February 1974, a spacecraft conceptual design review was conducted in November 1974. The Orbiter and Multiprobe utilized the same designs to the maximum extent possible to minimize costs. In addition, designs of subsystems or portions of subsystems from previous spacecraft designs (such as OSO and Intelsat) were utilized to the maximum extent possible with little or no modifications. This commonality in the two spacecraft designs also resulted in certain amounts of commonality in ground test equipment and test software as well as commonality in spacecraft flight operations and associated software. [ Extracted from: NOTHWANG, George J.,`Pioneer Venus Spacecraft Design and Operation', IEEE Transactions on Geoscience and Remote Sensing, vol. GE-18, No. 1, January 1980]. The main body of the spacecraft is a flat cylinder 2.5 meters in diameter and 1.2 meters high. In the upper end of this cylinder there is a circular equipment shelf with an area of 4.37 square meters on which all the scientific instruments and electronic subsystems are mounted. The shelf is mounted on the forward end of a thrust tube that connects the spacecraft to the launch vehicle. Below the shelf, 15 thermal louvers control heat radiation from an equipment compartment located between the shelf and the top of the spacecraft. A cylindrical solar array attached to the shelf by 24 brackets forms the circumference of the flat cylinder of the spacecraft. On top of the spacecraft, a 1.09 meter diameter, despun, high-gain, parabolic dish antenna is mounted on a mast so that its line of sight clears equipment mounted outside the spacecraft. The despun design allows the antenna to be mechanically directed to Earth from the spinning spacecraft. The antenna operates at S- and X-bands. The spacecraft also carries a solid propellant rocket motor. Including the antenna mast, the Orbiter is almost 4.5 meters high, and it weighed 553 kg when launched. The launch weight included 45 kg of scientific instruments and 179 kg of rocket propellant. Platform Descriptions ===================== MAGNETOMETER BOOM ----------------- An 4.8 meter long boom (188.9 inches) that was unfurled and extended automatically after launch. The magnetometer boom is located 240 degrees from the X-axis of the spacecraft coordinate system, measured in towards the Y-axis (in the spin direction) of the spin plane (XY). The total distance from the end of the boom to the orbiter spin axis is 5.94 meters (234.0 inches). " END_OBJECT = INSTRUMENT_HOST_INFORMATION OBJECT = INSTRUMENT_HOST_REFERENCE_INFO REFERENCE_KEY_ID = NOTHWANG1980 END_OBJECT = INSTRUMENT_HOST_REFERENCE_INFO END_OBJECT = INSTRUMENT_HOST /**************************************************************************** /* Body-Fixed Spherical Coordinate System /**************************************************************************** /* MODIFICATIONS: /* 930223 -- MKNIFFIN /* created template OBJECT = COORDINATE COORDINATE_SYSTEM_ID = BFS_CRDS OBJECT = COORDINFO COORDINATE_SYSTEM_NAME = "BODY FIXED SPHERICAL COORDS" COORDINATE_SYSTEM_CENTER_NAME = "UNK" COORDINATE_SYSTEM_REF_EPOCH = "UNK" COORDINATE_SYSTEM_DESC = " The body-fixed spherical coordinate system is the familiar Geographic coordinate system at Earth generalized to other planets. The system consists of the components Radius, Latitude, Longitude. The definition of the prime meridian varies for each planet as does the rotation period. It is crucial to know the exact definition of these variables when changing the reference body. Note: This coordinate system rotates with the reference body." END_OBJECT = COORDINFO OBJECT = VECTOR VECTOR_COMPONENT_TYPE = RANGE OBJECT = VECTORCOMP VECTOR_COMPONENT_ID = RADIUS REFERENCE_OBJECT_NAME = "N/A" REFERENCE_TARGET_NAME = "SPACECRAFT" VECTOR_COMPONENT_UNIT = "N/A" END_OBJECT = VECTORCOMP OBJECT = VECTORD VECTOR_COMPONENT_TYPE_DESC = " Radius: Distance from the reference body to the spacecraft." END_OBJECT = VECTORD END_OBJECT = VECTOR OBJECT = VECTOR VECTOR_COMPONENT_TYPE = LATITUDE OBJECT = VECTORCOMP VECTOR_COMPONENT_ID = PHI REFERENCE_OBJECT_NAME = "N/A" REFERENCE_TARGET_NAME = "SPACECRAFT" VECTOR_COMPONENT_UNIT = "N/A" END_OBJECT = VECTORCOMP OBJECT = VECTORD VECTOR_COMPONENT_TYPE_DESC = " phi = Latitude: The body-centered latitude of the spacecraft measured positive north of the reference body's equatorial plane." END_OBJECT = VECTORD END_OBJECT = VECTOR OBJECT = VECTOR VECTOR_COMPONENT_TYPE = LONGITUDE OBJECT = VECTORCOMP VECTOR_COMPONENT_ID = THETA REFERENCE_OBJECT_NAME = "N/A" REFERENCE_TARGET_NAME = "SPACECRAFT" VECTOR_COMPONENT_UNIT = "N/A" END_OBJECT = VECTORCOMP OBJECT = VECTORD VECTOR_COMPONENT_TYPE_DESC = " theta - Longitude: the longitude of the spacecraft measured eastward from the prime meridian of the reference body to the projection of the radius vector on the equatorial plane." END_OBJECT = VECTORD END_OBJECT = VECTOR END_OBJECT = COORDINATE /* ================================================================================ /****************** INSTRUMENT TEMPLATE ***************************************/ /* Template: Spacecraft Instrument Template Rev: 19890121 */ /* Note: The following templates form part of a standard */ /* set for the submission of a spacecraft instrument */ /* to the PDS. */ /* */ /* Hierarchy: SCINSTRUMENT */ /* INSTINFO */ /* INSTDETECT */ /* INSTELEC */ /* INSTFILTER */ /* INSTOPTICS */ /* SCINSTOFFSET */ /* INSTSECTION */ /* INSTSECTINFO */ /* INSTSECTFOVS */ /* INSTSECTPARM */ /* INSTSECTDET */ /* INSTSECTELEC */ /* INSTSECTFILT */ /* INSTSECTOPTC */ /* INSTMODEINFO */ /* INSTMODESECT */ /* INSTREFINFO */ /* REFERENCE */ /* REFAUTHORS */ /* */ OBJECT = SCINSTRUMENT SPACECRAFT_ID = PVO INSTRUMENT_ID = OETP /* Template: Instrument Information Template Rev: 19890121 */ /* Note: This template shall be completed for the */ /* instrument id entered in the ebinstrument or */ /* scinstrument template. */ OBJECT = INSTINFO INSTRUMENT_NAME = "PVO ELECTRON TEMPERATURE PROBE" INSTRUMENT_TYPE = "PLASMA INSTRUMENT" PI_PDS_USER_ID = LBRACE NAIF_DATA_SET_ID = "N/A" BUILD_DATE = UNK INSTRUMENT_MASS = UNK INSTRUMENT_HEIGHT = UNK INSTRUMENT_LENGTH = UNK INSTRUMENT_WIDTH = UNK INSTRUMENT_MANUFACTURER_NAME = UNK INSTRUMENT_SERIAL_NUMBER = UNK INSTRUMENT_DESC = " Pioneer Venus Orbiter Electron Temperature Probe J.P. Krehbiel, L.H. Brace, R.F. Theis, J.R. Cutler, W.H. Pinkus, and R.B. Kaplan IEEE Transactions on Geoscience and Remote Sensing January 1980 ABSTRACT - The Orbiter Electron Temperature Probe (OETP) instrumentation and measurement technique has been designed to perform in-situ measurements of electron temperature and electron and ion density in the ionosphere of Venus. Adaptive sweep voltage circuitry continuously tracks the changing electron temperature and spacecraft potential while auto-ranging electrometers adjust their gain in response to the changing plasma density. Control signals used in the instrument to achieve this automatic tracking provide a continuous monitor of the ionospheric parameters without telemetering each volt-ampere curve. Internal data storage permits high data rate sampling of selected raw characteristic curves for low rate transmission to Earth. These curves are used to verify or correct the inflight processed data. Sample in orbit measurements are presented to demonstrate instrument performance. I. INTRODUCTION THE PIONEER VENUS Orbiter Electron Temperature Probe (OETP) is one of several instruments used on the orbiter to perform in-situ measurements of the ionospheric plasma of Venus. The instrument employs cylindrical Langmuir probes to measure the electron temperature, Te, the electron and ion densities, Ne and Ni, and the spacecraft potential, Vs. To provide high spatial resolution of these parameters the instrument takes several hundred volt-ampere curves during each brief passage through the ionosphere. Owing to the limited telemetry rate available to each instrument, circuitry was included for inflight processing of the volt- ampere curves. Onboard storage of raw data from selected curves was provided to permit ground confirmation of the inflight processing method. Prior to launch, the instrument design was outlined briefly by Brace in a paper edited by Colin and Hunten (1977) [1]. The purpose of this paper is to present a a more detailed account of the instrument and some of the data acquired at Venus to illustrate how the instrument performs and how the ground data analysis is used to verify the flight measurements. Early results from this experiment have been reported [2] - [4]. II. THEORY OF THE METHOD The OETP is the latest spaceflight version of cylindrical electrostatic probe of Langmuir probe instrumentation. I. Langmuir and H. Mott-Smith, Jr., first reported use of the electrostatic probe in a laboratory plasma in 1924 [5]. The cylindrical probe technique has been used extensively to characterize the Earth's ionosphere [6], most recently on board the Atmosphere Explorer (AE) satellites [7]. The three AE instruments with their adaptive control circuitry and auto ranging electrometer provided the basis for the OETP instrument. Langmuir probe theory and application has been widely reported in the literature [1] - [8]. Here it will suffice to provide a brief description of the technique and to remind the reader of the theoretical volt-ampere curve produced by a Langmuir probe in a plasma as shown in Fig. 1. The curve begins in the ion saturation region with the probe potential sufficiently negative to prohibit plasma electrons from reaching the probe. At this point, current to the probe is due only to ions. In the retardation region where the probe potential is less negative, the more energetic electrons overcome the retarding potential, and produce an exponentially increasing current. The electron temperature Te determines the power of the exponential with lower Te yielding a narrower retarding region. In the electron saturation region, the probe is positive with respect to the plasma and therefore attracts additional electrons from the plasma. Equations appropriate to the three regions of the curve are given below. In the ion saturation region at 90 degree angle of attack [8] Ii = ANiew/pi(1 + kTi/miw2 + 2eV/miw2)1/2 (1) In the electron retardation region [2] Ie = ANee(kTe/2pime)1/2 exp(eV/kTe0. (2) In the electron saturation region [9], [10] Ie = (ANee/pi)(2eV/me)1/2 (3) where Ne electron density Ni ion density Te electron temperature Ti ion temperature A collector surface area w collector speed with respect to plasma k Boltzmann constant mi mean ion mass me electron mass V collector voltage with respect to the plasma e electron charge. OETP measurements are made with respect to spacecraft ground. This causes the voltage applied to the probe VA to be translated by the spacecraft potential Vs, as illustrated in Fig. 1. Special steps must be taken to account for this and to assure a stable spacecraft potential. This will be described later. III. THE EXPERIMENTAL ARRANGEMENT The OETP instrumentation system consists of two cylindrical sensors and a central electronics unit. Fig. 2 illustrates the relative position of the sensors and the larger appendages of the spacecraft. The radial sensor is mounted at the end of a 1-m boom which was folded against the solar array and deployed after Venus orbit insertion so as to be perpendicular to the spacecraft spin axis. The axial sensor is mounted on a fixed boom which places it 0.4 m away from the spacecraft forward surface. Because the axis of the axial sensor is parallel to the spin axis it maintains a relatively constant angle of attack to the incident plasma and is therefore not subject to spin modulation. To provide an adequate path for return current to the plasma, the spacecraft provides 1.73 m2 of exposed conducting area which is spacecraft ground. This area consists of a metal band around the solar array, a metal mesh over the outer kapton surface of the forward thermal blanket, and the outer surface of the magnetometer boom. Silicone rubber was applied to all solar cell edges and exposed electrical conductors making up the solar array to insulate these positive potential areas from the plasma and thus minimize the electron current they would otherwise collect producing a concomitant change in spacecraft potential. A. The Central Electronics The OETP central electronics unit contains independent electrometer amplifiers and adaptive sweep voltage circuitry to service each probe. Fig. 3 is a simplified functional block diagram of the system. Each amplifier feeds its output into the common A/D converter and data handling circuitry. The autoranging electrometer and adaptive sweep voltage circuits are identical to that employed in the three AE missions [7]. The signal multiplexing (Mux), A/D conversion, data formatting, and First-In/First-Out memory (FIFO) are new features to permit the inflight processing and recovery of data, a capability required by the lower data rate available from the orbiter. The radial probe electrometer has a sensitivity range of 1 x 10 to the neg. 10 power to 1 x 10 to the neg. 6 power A/V, while the axial probe electrometer has a sensitivity range of 1 x 10 to the neg. nine power to 1 x 10 to the neg. 5 power A/V. Electrometer sensitivity is automatically adjusted to one of 1024 possible values. Electrical power is provided by a common dc/dc converter having separate floating outputs for each of the two electrometers. Adaptive circuitry is provided to adjust the sweep voltage to resolve that region of the volt-ampere curve needed to derive Ni, Ne, Te, and Vs and to track changes in Te and Vs encountered along the orbit. The adaptive process provides a more continuous monitor of these plasma parameters than could be obtained if we were to rely solely on ground-based analysis of volt-ampere curves produced by the instrument, given the available data rate. The VA generator converges on the proper starting value VA Start, and the proper rate of change VA Slope through an iterative process involving the auto-ranging electrometer and the adaptive VA circuitry. When the adaptive process is completed, usually within two sweeps, the curves are properly framed to maximize the resolution of the measured parameters. Once proper framing had been achieved, it is maintained by slight adjustments in VA Start, VA Slope, and electrometer gain which track the changes in electron temperature, density, and spacecraft potential. An idealized 1/2-s instrument measurement cycle of applied voltage, and the resulting electrometer output for a properly framed curve are shown in Fig. 4. Also shown are the parameters used to carry out the adaptive process and to achieve the inflight analysis. The cycle begins at time T0 by setting VA equal to VA Start as determined from parameters measured during the previous curve. After a settling time the electrometer auto-ranging algorithm is initiated to adjust the electrometer gain as needed to drive its output to the -3.30-Vthreshold. Current to the sensor at this time is entirely ion current and is used to determine Ni. At time T1 the VA is increased linearly at a rate also determined from the previous curve. The VA and electrometer outputs are monitored by level detectors. When the electrometer output reaches +1.41 V a level detector starts a counter and the value of VA at T2 is measured. When the electrometer output reaches +9.50 V, a second level detector stops the counter and the value of VA at T3 is measured. At T3 the electrometer downranges by one decade and displays the rest of the volt-ampere curve until the linear sweep is stopped at T4. At T4 a fixed 2-V step is added to drive the sensor into the electron saturation region. The electrometer then downranges until its output is on scale and a reading of output voltage and gain are taken and used to determine Ne. In each 1/2-s instrument cycle we are thus able to determine, from each electrometer, Ni from the gain and electrometer output just prior to T1, Te from the change in VA which produced a factor of e change in electrometer output, and Ne from the gain and electrometer output during the Ne sample time. The curve framing process continues by automatically computing new values of VA Slope and VA Start. VA Slope is computed from our definition of a properly framed curve which requires that the full amplitude of VA be ten times the value of the change in VA from T2 to T3 when the 1.41- and 9.50-V thresholds are reached. VA Start is computed using (4) which places the exponential electron retardation region such that the 9.50-V threshold is reached at 86 percent of the sweep interval. VA Start = 8.6 VA at T2 - 7.6 VA at T3. (4) If the VA at T1 does not provide a net ion current to the collector or if the electrometer fails to reach the +9.50-V output, called the T3 threshold, the VA generator will preset to the 'fault' condition for the next sweep causing VA to start at -7 V and sweep up to +5V. The fault sweep amplitude is sufficient to locate the operating region of the volt-ampere curve and to permit the convergence algorithm to repeat at the beginning of the following sweep. As a safeguard against unforeseen difficulties which might cause our adaptive approach to fail, a fixed amplitude sweep mode can be selected by ground command in which a sequence of high and low voltage sweeps are applied to either or both sensors. The high VA was -7 to +5 V and the low VA was -2 to +1 V. In this mode a bias voltage of +/- 1 V can be added to account for Vs uncertainties. The fixed sweep mode is not normally used because the adaptive mode yields better resolved stored curves. B. The Sensors and Booms A sensor with its guard electrode and a portion of the boom are schematically shown in Fig. 5. The guard electrode, driven at VA, is the exposed inner shield of a rigid triaxial boom fabricated with titanium and teflon. The outer triaxial shield is held at spacecraft ground potential. A special white conductive paint, GSFC Code No. NS43C [11], was applied to the outer surface of the booms to provide thermal control. Flight sensors were screwed onto the boom center conductor and held in place with a high temperature silicone (Dow Corning X 12561, silver filled for electrical conductivity) to assure that the sensors remained in place during the launch vibration. The accuracy of the temperature measurements is affected by the characteristics of the sensor surface [12]. In particular, the work function of different crystal surfaces can vary by as much as several tenths of a volt and thus introduce an uncertainty in the value of V in (1) - (3). To reduce this error the collectors were fabricated using a chemical vapor deposition (CVD) process. Studies of the CVD Rhenium show that Rhenium deposited by the pyrolyctic decomposition of Rhenium pentachloride (ReCl5) show a very high degree of crystal orientation. Rhenium deposited in this manner exhibits a (0001) preferred orientation [13] perpendicular to the plane of growth. Cylindrical tubes of this type have yielded uniform vacuum work functions of 5.1 eV. Molybdenum deposited from MoCl6 also shows a very high degree of crystal orientation. Thus both materials become candidates for sensor materials. Fig. 6 shows part of a cross section of a collector having a CVD Rhenium surface deposited on a polycrystalline subtrate. Flight collectors were selected on the basis of examining similar cross sections cut from one end of the collector and from volt-ampere curves taken in laboratory plasmas. The radial collector surface is Rhemium and the axial is Molybdenum. C. Measurements Format The orbiter is able to operate in several data formats and at spacecraft data rates from 16 to 2048 b/s. The OETP is designed for optimum operation when its output data rates are 80, 128, or 160 b/s, one of which is normally used during a periapsis pass. Various instrument data formats can be selected by command to provide for more or less dense coverage depending on such factors as spacecraft bit rate and whether the OETP data system is dedicated to one sensor or shared by both of them. IV. Verification of Inflight Analysis To permit ground calibration of the values of Ni, Ne, and Te determined by the inflight processing, the instrument periodically samples volt-ampere curves from either or both electrometers. The electrometer output is measured at 50 equally spaced points between T1 and T4. The FIFO memory is used to store the fifty measurements , made at 1132 b/s, for later readout at the lower spacecraft telemetry rate. Fig. 7 illustrates the ground analysis of such a stored curve taken from orbit 112. The solid line represents a least squares fit of a straight line (ion current) and exponential (electron current) to the actual data points within the electron retardation region. V. Illustration of Operation at Venus Fig. 8 is a computer plot of the values of Te and Ne taken from a single pass of the orbiter through the nightside ionosphere. The line segments connect the inflight values and reveal the small-scale spatial structure which is often present. The asterisks represent the values of Te and Ne derived later by computer fitting stored volt-ampere curves of the type illustrated in Fig. 7. Values derived from the stored curves are used to normalize the inflight processed data. Thus through the use of on-board processing of curves, high spatial resolution is achieved without sacrificing the accuracy provided by ground computer fitting of raw volt-ampere curves. As of this writing more than 250 passes through the ionosphere of Venus have been completed and the instrument continues to operate well. ACKNOWLEDGEMENT The authors gratefully acknowledge the aid of L.R.O. Storey in the testing of candidate collectors in the low temperature plasma chamber at the Centre de Recherches en Physique de L'Environment Terrestre en Planetaire in Orleans, France REFERENCES L.H. Brace, 'Orbiter electron temperature Probe', L. Colin and D.M. Hunten, Eds. Space Sci. Rev., vol. 20, no. 4, p.454, June 1977. L.H. Brace, R.F. Theis, J.P. Krehbiel, A.F. Nagy, T.M. Donahue, M.E. McElroy, and A. Pedersen, 'Electron temperatures and densities in the Venus ionosphere', Science, vol. 203, p. 763, Feb. 23, 1979. L.H. Brace, H.A. Taylor Jr., P.A. Cloutier, R.E. Daniell Jr., and A.F. Nagy, 'On the configuration of the nightside Venus ionopause', Geophys. Res. Lett., vol. 6, p. 345, 1979. L.H. Brace, R.F. Theis, H.B. Niemann, H.G. Mayr, W.R. Hoegy, and A.F. Nagy, 'Empirical models of the electron temperature and density in the nightside Venus ionosphere', Science, vol. 205, p. 102, 1979. I. Langmuir, and H. Mott-Smith, Jr., 'Studies of the electric discharges in gases at low pressures', Gen. Elec. Rev., p. 616, Sept. 1924. L.H. Brace, 'Global structure of ionosphere temperature', in Space Research X. Amsterdam, The Netherlands: North-Holland, p. 633, 1970. L.H. Brace, R.F. Theis, and A. Dalgarno, 'The cylindrical electrostatic probes for atmosphere explorer -C, -D, -E', Science, vol. 8, no. 4, p. 341, Apr. 1973. W.R. Hoegy and L.E. Wharton, 'Current to moving spherical and cylindrical electrostatic probes', J. Appl. Phys., vol. 44, no. 12, p. 5365-5371, 1973. H. Mott-Smith and I. Langmuir, 'The theory of collectors in gaseous discharges', Phys. Rev., vol. 28, pp. 727-763, 1926. N.W. Spencer, L.H. Brace, G.R. Carignan, D.R. Taeusch, and H.B. Niemann, 'Electron and molecular nitrogen temperature and density in the thermosphere', J. Geophys. Res., vol. 70, pp. 2665-2698, 1965. M.C. Shai, 'Formulation of electrically conductive thermal- control coatings ', NASA Tech. Paper 1218, Apr. 1978. D. Smith, 'The application of Langmuir probes to the measurement of very low electron temperatures', Planet. Space Sci., vol. 20, p. 1721, 1972. L. Yang, 'Preparation & evaluation of CVD rhenium thermionic emitters', in The Third Annual Conference on Chemical Vapor Deposition, F.A. Glaski, Ed., American Nuclear Society, 1972." SCIENTIFIC_OBJECTIVES_SUMMARY = NONE INSTRUMENT_CALIBRATION_DESC = " To permit ground calibration of the values of Ni, Ne, and Te determined by the inflight processing, the instrument periodically samples volt-ampere curves from either or both electrometers. The electrometer output is measured at 50 equally spaced points between T1 and T4. The FIFO memory is used to store the fifty measurements , made at 1132 b/s, for later readout at the lower spacecraft telemetry rate. Fig. 7 illustrates the ground analysis of such a stored curve taken from orbit 112. The solid line represents a least squares fit of a straight line (ion current) and exponential (electron current) to the actual data points within the electron retardation region." OPERATIONAL_CONSID_DESC = "N/A" END_OBJECT = INSTINFO /* Template: Instrument Detector Template Rev: 19890121 */ /* Note: This template shall be repeated for each */ /* detector utilized by an instrument. */ OBJECT = INSTDETECT DETECTOR_ID = PVOETP DETECTOR_TYPE = "N/A" DETECTOR_ASPECT_RATIO = "N/A" MINIMUM_WAVELENGTH = "N/A" MAXIMUM_WAVELENGTH = "N/A" NOMINAL_OPERATING_TEMPERATURE = "N/A" DETECTOR_DESC = " The Sensors and Booms A sensor with its guard electrode and a portion of the boom are schematically shown in Fig. 5. The guard electrode, driven at VA, is the exposed inner shield of a rigid triaxial boom fabricated with titanium and teflon. The outer triaxial shield is held at spacecraft ground potential. A special white conductive paint, GSFC Code No. NS43C [11], was applied to the outer surface of the booms to provide thermal control. Flight sensors were screwed onto the boom center conductor and held in place with a high temperature silicone (Dow Corning X 12561, silver filled for electrical conductivity) to assure that the sensors remained in place during the launch vibration. The accuracy of the temperature measurements is affected by the characteristics of the sensor surface [12]. In particular, the work function of different crystal surfaces can vary by as much as several tenths of a volt and thus introduce an uncertainty in the value of V in (1) - (3). To reduce this error the collectors were fabricated using a chemical vapor deposition (CVD) process. Studies of the CVD Rhenium show that Rhenium deposited by the pyrolyctic decomposition of Rhenium pentachloride (ReCl5) show a very high degree of crystal orientation. Rhenium deposited in this manner exhibits a (0001) preferred orientation [13] perpendicular to the plane of growth. Cylindrical tubes of this type have yielded uniform vacuum work functions of 5.1 eV. Molybdenum deposited from MoCl6 also shows a very high degree of crystal orientation. Thus both materials become candidates for sensor materials. Fig. 6 shows part of a cross section of a collector having a CVD Rhenium surface deposited on a polycrystalline subtrate. Flight collectors were selected on the basis of examining similar cross sections cut from one end of the collector and from volt-ampere curves taken in laboratory plasmas. The radial collector surface is Rhemium and the axial is Molybdenum." /******************************************************************************/ SENSITIVITY_DESC = " " /******************************************************************************/ END_OBJECT = INSTDETECT /* Template: Instrument Electronics Template Rev: 19890121 */ /* Note: This template shall be repeated for each */ /* electronics id description utilized by an */ /* instrument. */ OBJECT = INSTELEC ELECTRONICS_ID = "PVOETP" ELECTRONICS_DESC = " A. The Central Electronics The OETP central electronics unit contains independent electrometer amplifiers and adaptive sweep voltage circuitry to service each probe. Fig. 3 is a simplified functional block diagram of the system. Each amplifier feeds its output into the common A/D converter and data handling circuitry. The autoranging electrometer and adaptive sweep voltage circuits are identical to that employed in the three AE missions [7]. The signal multiplexing (Mux), A/D conversion, data formatting, and First-In/First-Out memory (FIFO) are new features to permit the inflight processing and recovery of data, a capability required by the lower data rate available from the orbiter. The radial probe electrometer has a sensitivity range of 1 x 10 to the neg. 10 power to 1 x 10 to the neg. 6 power A/V, while the axial probe electrometer has a sensitivity range of 1 x 10 to the neg. nine power to 1 x 10 to the neg. 5 power A/V. Electrometer sensitivity is automatically adjusted to one of 1024 possible values. Electrical power is provided by a common dc/dc converter having separate floating outputs for each of the two electrometers. Adaptive circuitry is provided to adjust the sweep voltage to resolve that region of the volt-ampere curve needed to derive Ni, Ne, Te, and Vs and to track changes in Te and Vs encountered along the orbit. The adaptive process provides a more continuous monitor of these plasma parameters than could be obtained if we were to rely solely on ground-based analysis of volt-ampere curves produced by the instrument, given the available data rate. The VA generator converges on the proper starting value VA Start, and the proper rate of change VA Slope through an iterative process involving the auto-ranging electrometer and the adaptive VA circuitry. When the adaptive process is completed, usually within two sweeps, the curves are properly framed to maximize the resolution of the measured parameters. Once proper framing had been achieved, it is maintained by slight adjustments in VA Start, VA Slope, and electrometer gain which track the changes in electron temperature, density, and spacecraft potential. An idealized 1/2-s instrument measurement cycle of applied voltage, and the resulting electrometer output for a properly framed curve are shown in Fig. 4. Also shown are the parameters used to carry out the adaptive process and to achieve the inflight analysis. The cycle begins at time T0 by setting VA equal to VA Start as determined from parameters measured during the previous curve. After a settling time the electrometer auto-ranging algorithm is initiated to adjust the electrometer gain as needed to drive its output to the -3.30-Vthreshold. Current to the sensor at this time is entirely ion current and is used to determine Ni. At time T1 the VA is increased linearly at a rate also determined from the previous curve. The VA and electrometer outputs are monitored by level detectors. When the electrometer output reaches +1.41 V a level detector starts a counter and the value of VA at T2 is measured. When the electrometer output reaches +9.50 V, a second level detector stops the counter and the value of VA at T3 is measured. At T3 the electrometer downranges by one decade and displays the rest of the volt-ampere curve until the linear sweep is stopped at T4. At T4 a fixed 2-V step is added to drive the sensor into the electron saturation region. The electrometer then downranges until its output is on scale and a reading of output voltage and gain are taken and used to determine Ne. In each 1/2-s instrument cycle we are thus able to determine, from each electrometer, Ni from the gain and electrometer output just prior to T1, Te from the change in VA which produced a factor of e change in electrometer output, and Ne from the gain and electrometer output during the Ne sample time. The curve framing process continues by automatically computing new values of VA Slope and VA Start. VA Slope is computed from our definition of a properly framed curve which requires that the full amplitude of VA be ten times the value of the change in VA from T2 to T3 when the 1.41- and 9.50-V thresholds are reached. VA Start is computed using (4) which places the exponential electron retardation region such that the 9.50-V threshold is reached at 86 percent of the sweep interval. VA Start = 8.6 VA at T2 - 7.6 VA at T3. (4) If the VA at T1 does not provide a net ion current to the collector or if the electrometer fails to reach the +9.50-V output, called the T3 threshold, the VA generator will preset to the 'fault' condition for the next sweep causing VA to start at -7 V and sweep up to +5V. The fault sweep amplitude is sufficient to locate the operating region of the volt-ampere curve and to permit the convergence algorithm to repeat at the beginning of the following sweep. As a safeguard against unforeseen difficulties which might cause our adaptive approach to fail, a fixed amplitude sweep mode can be selected by ground command in which a sequence of high and low voltage sweeps are applied to either or both sensors. The high VA was -7 to +5 V and the low VA was -2 to +1 V. In this mode a bias voltage of +/- 1 V can be added to account for Vs uncertainties. The fixed sweep mode is not normally used because the adaptive mode yields better resolved stored curves." END_OBJECT = INSTELEC /* Template: Instrument Filter Template Rev: 19890121 */ /* Note: This template shall be repeated for each */ /* filter utilized by an instrument. */ OBJECT = INSTFILTER FILTER_NUMBER = "N/A" FILTER_NAME = "N/A" FILTER_TYPE = "N/A" MINIMUM_WAVELENGTH = "N/A" CENTER_FILTER_WAVELENGTH = "N/A" MAXIMUM_WAVELENGTH = "N/A" MEASUREMENT_WAVE_CALBRT_DESC = "N/A" END_OBJECT = INSTFILTER /* Template: Instrument Optics Template Rev: 19890121 */ /* Note: This template shall be completed for each */ /* optical instrument. */ OBJECT = INSTOPTICS TELESCOPE_ID = "N/A" TELESCOPE_FOCAL_LENGTH = "N/A" TELESCOPE_DIAMETER = "N/A" TELESCOPE_F_NUMBER = "N/A" TELESCOPE_RESOLUTION = "N/A" TELESCOPE_TRANSMITTANCE = "N/A" TELESCOPE_T_NUMBER = "N/A" TELESCOPE_T_NUMBER_ERROR = "N/A" TELESCOPE_SERIAL_NUMBER = "N/A" OPTICS_DESC = "N/A" END_OBJECT = INSTOPTICS /* Template: Spacecraft Instrument Offset Template Rev: 19890121 */ /* Note: This template shall be completed for each */ /* platform used for instrument positioning. */ OBJECT = SCINSTOFFSET PLATFORM_OR_MOUNTING_NAME = "OETP BOOM" CONE_OFFSET_ANGLE = UNK CROSS_CONE_OFFSET_ANGLE = UNK TWIST_OFFSET_ANGLE = UNK INSTRUMENT_MOUNTING_DESC = " The OETP instrumentation system consists of two cylindrical sensors and a central electronics unit. Fig. 2 illustrates the relative position of the sensors and the larger appendages of the spacecraft. The radial sensor is mounted at the end of a 1-m boom which was folded against the solar array and deployed after Venus orbit insertion so as to be perpendicular to the spacecraft spin axis. The axial sensor is mounted on a fixed boom which places it 0.4 m away from the spacecraft forward surface. Because the axis of the axial sensor is parallel to the spin axis it maintains a relatively constant angle of attack to the incident plasma and is therefore not subject to spin modulation." END_OBJECT = SCINSTOFFSET /* Template: Instrument Section Template Rev: 19890121 */ /* Note: This template group shall be repeated for each */ /* instrument section. */ OBJECT = INSTSECTION SECTION_ID = PVOETP /* Template: Instrument Section Information Template Rev: 19890121 */ /* Note: This section shall be completed for each */ /* instrument section id entered in the instsection */ /* template. */ OBJECT = INSTSECTINFO SCAN_MODE_ID = UNK DATA_RATE = "N/A" SAMPLE_BITS = "N/A" TOTAL_FOVS = "N/A" /* Template: Instrument Section Fields Of View Template Rev: 19890121 */ /* Note: This template shall be repeated for each */ /* instrument section fields of view. */ OBJECT = INSTSECTFOVS FOV_SHAPE_NAME = UNK HORIZONTAL_PIXEL_FOV = UNK VERTICAL_PIXEL_FOV = UNK HORIZONTAL_FOV = UNK VERTICAL_FOV = UNK FOVS = UNK END_OBJECT = INSTSECTFOVS END_OBJECT = INSTSECTINFO /* Template: Instrument Section Parameter Template Rev: 19890121 */ /* Note: This template shall be repeated for each */ /* instrument section parameter. */ OBJECT = INSTSECTPARM INSTRUMENT_PARAMETER_NAME = "VOLT/AMPERE RATIO" MINIMUM_INSTRUMENT_PARAMETER = 1.0e-10 MAXIMUM_INSTRUMENT_PARAMETER = 1.0e-5 NOISE_LEVEL = "N/A" INSTRUMENT_PARAMETER_UNIT = "AMPERES/VOLT" SAMPLING_PARAMETER_NAME = TIME MINIMUM_SAMPLING_PARAMETER = "N/A" MAXIMUM_SAMPLING_PARAMETER = "N/A" SAMPLING_PARAMETER_INTERVAL = "N/A" SAMPLING_PARAMETER_RESOLUTION = "N/A" SAMPLING_PARAMETER_UNIT = SECONDS END_OBJECT = INSTSECTPARM /* Template: Instrument Section Detector Template Rev: 19890121 */ /* Note: This template shall be repeated for each */ /* instrument section detector id. */ OBJECT = INSTSECTDET DETECTOR_ID = OETP_RADIAL END_OBJECT = INSTSECTDET OBJECT = INSTSECTDET DETECTOR_ID = OETP_AXIAL END_OBJECT = INSTSECTDET /* Template: Instrument Section Electronics Template Rev: 19890121 */ /* Note: This template shall be repeated for each */ /* instrument section electronics component. */ OBJECT = INSTSECTELEC ELECTRONICS_ID = PVOETP END_OBJECT = INSTSECTELEC /* Template: Instrument Section Filter Template Rev: 19890121 */ /* Note: This template shall be repeated for each */ /* instrument section filter. */ OBJECT = INSTSECTFILT FILTER_NUMBER = "N/A" END_OBJECT = INSTSECTFILT /* Template: Instrument Section Optics Template Rev: 19890121 */ /* Note: This template shall be repeated for each */ /* instrument section telescope. */ OBJECT = INSTSECTOPTC TELESCOPE_ID = "N/A" END_OBJECT = INSTSECTOPTC END_OBJECT = INSTSECTION /* Template: Instrument Mode Information Template Rev: 19890121 */ /* Note: This template shall be repeated for each */ /* instrument mode. */ OBJECT = INSTMODEINFO INSTRUMENT_MODE_ID = UNK GAIN_MODE_ID = UNK DATA_PATH_TYPE = UNK INSTRUMENT_POWER_CONSUMPTION = UNK INSTRUMENT_MODE_DESC = UNK /* Template: Instrument Mode Section Information Template Rev: 19890121 */ /* Note: This template shall be repeated for each association of an */ /* instrument mode to an instrument section. */ OBJECT = INSTMODESECT SECTION_ID = UNK END_OBJECT = INSTMODESECT END_OBJECT = INSTMODEINFO /* Template: Instrument Reference Information Template Rev: 19890121 */ /* Note: The following template form part of a standard */ /* set for the submission of a publication reference */ /* to the PDS. */ OBJECT = INSTREFINFO REFERENCE_KEY_ID = BRACE1977 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "ELECTRON PROBES" JOURNAL_NAME = "SPACE SCIENCE REVIEWS" PUBLICATION_DATE = 1977-06 REFERENCE_DESC = " Brace, L.H., 'Orbiter electron temperature Probe', L. Colin and D.M. Hunten, Eds. Space Sci. Rev., vol. 20, no. 4, p.454, June 1977." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "LAURENCE H. BRACE" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = INSTREFINFO OBJECT = INSTREFINFO REFERENCE_KEY_ID = BRACEETAL1979A OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF VENUS" JOURNAL_NAME = SCIENCE PUBLICATION_DATE = 1979-02-23 REFERENCE_DESC = " Brace, L.H., R.F. Theis, J.P. Krehbiel, A.F. Nagy, T.M. Donahue, M.E. McElroy, and A. Pedersen, 'Electron temperatures and densities in the Venus ionosphere', Science, vol. 203, p. 763, Feb. 23, 1979." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "LAURENCE H. BRACE" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = INSTREFINFO OBJECT = INSTREFINFO REFERENCE_KEY_ID = BRACEETAL1979B OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF VENUS" JOURNAL_NAME = "GEOPHYSICAL RESEARCH LETTERS" PUBLICATION_DATE = 1979 REFERENCE_DESC = " Brace, L.H., H.A. Taylor Jr., P.A. Cloutier, R.E. Daniell Jr., and A.F. Nagy, 'On the configuration of the nightside Venus ionopause', Geophys. Res. Lett., vol. 6, p. 345, 1979." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "LAURENCE H. BRACE" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = INSTREFINFO OBJECT = INSTREFINFO REFERENCE_KEY_ID = BRACEETAL1979C OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF VENUS" JOURNAL_NAME = SCIENCE PUBLICATION_DATE = 1979 REFERENCE_DESC = " Brace, L.H., R.F. Theis, H.B. Niemann, H.G. Mayr, W.R. Hoegy, and A.F. Nagy, 'Empirical models of the electron temperature and density in the nightside Venus ionosphere', Science, vol. 205, p. 102, 1979." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "LAURENCE H. BRACE" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = INSTREFINFO OBJECT = INSTREFINFO REFERENCE_KEY_ID = LANGMUIRETAL1924 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "ELECTRON PROBES" JOURNAL_NAME = "GENERAL ELECTRONICS REVIEWS" PUBLICATION_DATE = 1924-09 REFERENCE_DESC = " Langmuir, I. and H. Mott-Smith, Jr., 'Studies of the electric discharges in gases at low pressures', Gen. Elec. Rev., p. 616, Sept. 1924." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "I. LANGMUIR" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = INSTREFINFO OBJECT = INSTREFINFO REFERENCE_KEY_ID = BRACE1970 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF EARTH" JOURNAL_NAME = "SPACE RESEARCH" PUBLICATION_DATE = 1970 REFERENCE_DESC = " Brace, L.H., 'Global structure of ionosphere temperature', in Space Research X. Amsterdam, The Netherlands: North-Holland, p. 633, 1970." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "LAURENCE H. BRACE" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = INSTREFINFO OBJECT = INSTREFINFO REFERENCE_KEY_ID = BRACEETAL1973 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "ELECTRON PROBES" JOURNAL_NAME = SCIENCE PUBLICATION_DATE = 1973-04 REFERENCE_DESC = " Brace, L.H., R.F. Theis, and A. Dalgarno, 'The cylindrical electrostatic probes for atmosphere explorer -C, -D, -E', Science, vol. 8, no. 4, p. 341, Apr. 1973." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "LAURENCE H. BRACE" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = INSTREFINFO OBJECT = INSTREFINFO REFERENCE_KEY_ID = HOEGYETAL1973 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "ELECTRON PROBES" JOURNAL_NAME = "JOURNAL OF APPLIED PHYSICS" PUBLICATION_DATE = 1973 REFERENCE_DESC = " Hoegy, W.R., and L.E. Wharton, 'Current to moving spherical and cylindrical electrostatic probes', J. Appl. Phys., vol. 44, no. 12, p. 5365-5371, 1973." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "W.R. HOEGY" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = INSTREFINFO OBJECT = INSTREFINFO REFERENCE_KEY_ID = MOTTSMITHETAL1926 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "ELECTRON PROBES" JOURNAL_NAME = "PHYSICS REVIEWS" PUBLICATION_DATE = 1926 REFERENCE_DESC = " Mott-Smith, H. and I. Langmuir, 'The theory of collectors in gaseous discharges', Phys. Rev., vol. 28, pp. 727-763, 1926." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "H. MOTT-SMITH" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = INSTREFINFO OBJECT = INSTREFINFO REFERENCE_KEY_ID = SPENCERETAL1965 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "THERMOSPHERE OF EARTH" JOURNAL_NAME = "JOURNAL OF GEOPHYSICAL RESEARCH" PUBLICATION_DATE = 1965 REFERENCE_DESC = " Spencer, N.W., L.H. Brace, G.R. Carignan, D.R. Taeusch, and H.B. Niemann, 'Electron and molecular nitrogen temperature and density in the thermosphere', J. Geophys. Res., vol. 70, pp. 2665-2698, 1965." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "N.W. SPENCER" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = INSTREFINFO OBJECT = INSTREFINFO REFERENCE_KEY_ID = SHAI1978 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "ELECTRON PROBES" JOURNAL_NAME = "NASA TECHNICAL PAPER 1218" PUBLICATION_DATE = 1978-04 REFERENCE_DESC = " Shai, M.C., 'Formulation of electrically conductive thermal- control coatings ', NASA Tech. Paper 1218, Apr. 1978." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "M.C. SHAI" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = INSTREFINFO OBJECT = INSTREFINFO REFERENCE_KEY_ID = SMITH1972 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "ELECTRON PROBES" JOURNAL_NAME = "PLANETARY SPACE SCIENCE" PUBLICATION_DATE = 1972 REFERENCE_DESC = " Smith, D., 'The application of Langmuir probes to the measurement of very low electron temperatures', Planet. Space Sci., vol. 20, p. 1721, 1972." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "D. SMITH" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = INSTREFINFO OBJECT = INSTREFINFO REFERENCE_KEY_ID = YANG1972 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "ELECTRON PROBES" JOURNAL_NAME = "N/A" PUBLICATION_DATE = 1972 REFERENCE_DESC = " Yang, L., 'Preparation & evaluation of CVD rhenium thermionic emitters', in The Third Annual Conference on Chemical Vapor Deposition, F.A. Glaski, Ed., American Nuclear Society, 1972." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "L. YANG" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = INSTREFINFO END_OBJECT = SCINSTRUMENT ================================================================================ /******************** DATASET TEMPLATE ****************************************/ /* Template: Spacecraft Data Set Template Rev: 19890121 */ /* Note: The following templates form part of a standard set */ /* for the submission of a single dataset to the PDS. */ /* Hierarchy: SCDATASET */ /* DATASETINFO */ /* DATASETTARG */ /* DSPARMINFO */ /* SCDSHOST */ /* DSREFINFO */ /* REFERENCE */ /* REFAUTHORS */ OBJECT = SCDATASET DATA_SET_ID = "PVO-V-OETP-5-BOWSHOCKLOCATION-V1.0" OBJECT = DATASETINFO DATA_SET_NAME = "PVO VENUS ELECT TEMP PROBE DERVD BOW SHOCK LOCATION VER 1.0" DATA_SET_COLLECTION_MEMBER_FLG = N START_TIME = "UNK" STOP_TIME = "UNK" NATIVE_START_TIME = UNK NATIVE_STOP_TIME = UNK DATA_OBJECT_TYPE = TABLE DATA_SET_RELEASE_DATE = 1993-10-01 PROCESSING_LEVEL_ID = 5 PRODUCER_FULL_NAME = "DR. ROBERT F. THEIS" PRODUCER_INSTITUTION_NAME = "GODDARD SPACE FLIGHT CENTER" SOFTWARE_FLAG = Y DETAILED_CATALOG_FLAG = N PROCESSING_START_TIME = UNK PROCESSING_STOP_TIME = UNK DATA_SET_DESC = " The Bow Shock File. This file gives the orbit-by-orbit times and locations of the bow shock crossings, which are characterized by distinct changes in Ne. Multiple shock crossing are listed if they are sufficiently separated to be resolved accurately. (Bow shock crossings will be evident in the High Resolution Ne File when they occurred within 30 minutes of periapsis). The ionopause and bow shock crossing times and locations are easily identified in the high resolution Ne measurements (Theis et al., 1980). These files contain the UT, altitude, latitude, SZA and local time of each crossing. The bow shock is a much more discrete feature in the data than the ionopause. Multiple shock crossings sometimes occur because the shock often moves at higher velocities than the satellite. In these cases, only the outer most shock crossing is recorded, unless the separation between the crossings is greater than a minute or two. The occurrence of multiple shocks in the Bow Shock File provides a record of the orbits in which the solar wind itself was probably highly variable. Because of the geometry of the orbit, most shock crossings were in the range of 45 to 135 deg. SZA. However, the nose region of the shock was explored between 1985 and 1987 when PVO periapsis was near the equator and was at altitudes between 2000 and 2300 km. During these years near solar minimum the nose of the shock often moved down into that altitude range (Russell et al, 1988). During the subsolar passages of these years, the orbit approximately paralleled the shock, sometimes inside, sometimes outside, thus providing interesting snapshots of its movements." /****************************************************************************/ CONFIDENCE_LEVEL_NOTE = " The bow shock is selected from 200 minute pass plots by marking the UT of the sharp change in the amplitude of Ne at the shock discontinuity. The resolution of the shock crossing time is of the order of 1 minute on these plots, but this could be improved to a few seconds if expanded plots were used. There is no plan currently to provide the ultimate resolution available in bow shock crossing time and location." /****************************************************************************/ END_OBJECT = DATASETINFO OBJECT = DATASETTARG TARGET_NAME = VENUS END_OBJECT = DATASETTARG OBJECT = DSPARMINFO SAMPLING_PARAMETER_NAME = TIME SAMPLING_PARAMETER_RESOLUTION = "N/A" MINIMUM_SAMPLING_PARAMETER = "N/A" MAXIMUM_SAMPLING_PARAMETER = "N/A" SAMPLING_PARAMETER_INTERVAL = 12 MINIMUM_AVAILABLE_SAMPLING_INT = "N/A" SAMPLING_PARAMETER_UNIT = SECOND DATA_SET_PARAMETER_NAME = "POSITION VECTOR" NOISE_LEVEL = "N/A" DATA_SET_PARAMETER_UNIT = "N/A" END_OBJECT = DSPARMINFO OBJECT = SCDSHOST INSTRUMENT_HOST_ID = PVO INSTRUMENT_ID = OETP END_OBJECT = SCDSHOST OBJECT = DSREFINFO REFERENCE_KEY_ID = ALEXANDERETAL1985 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF VENUS" JOURNAL_NAME = "GEOPHYSICAL RESEARCH LETTERS" PUBLICATION_DATE = 1985 REFERENCE_DESC = " Alexander, C. J., C. T. Russell, Solar cycle dependence of the location of the Venus bow shock, Geophys. Res. Lett., 12, 369, 1985." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "C. J. ALEXANDER" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "C. T. RUSSELL" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO OBJECT = DSREFINFO REFERENCE_KEY_ID = BRACEETAL1987 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF VENUS" JOURNAL_NAME = "JOURNAL OF GEOPHYSICAL RESEARCH" PUBLICATION_DATE = 1987 REFERENCE_DESC = " Brace, L. H., W. T. Kasprzak, H. A. Taylor, Jr., R. F. Theis, C. T. Russell, A. Barnes, J. D. Mihalov, and D. M. Hunten, 'The ionotail of Venus: Its configuration and evidence for ion escape, J. Geophys. Res., 92, 15, 1987." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. L. H. BRACE" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. W. T. KASPRZAK" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. H. A. TAYLOR JR." END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. R. F. THEIS" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. C. T. RUSSELL" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. A. BARNES" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. J. D. MIHALOV" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. D. M. HUNTEN" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO OBJECT = DSREFINFO REFERENCE_KEY_ID = BRACEETAL1988 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF VENUS" JOURNAL_NAME = "JOURNAL OF GEOPHYSICAL RESEARCH" PUBLICATION_DATE = 1988 REFERENCE_DESC = " Brace, L. H., W. R. Hoegy, and R. F. Theis, 'Solar EUV measurements at Venus based on photoelectron emission from the Pioneer Venus Langmuir probe', J. Geophys. Res., 93, 7282, 1988." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. L. H. BRACE" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. W. R. HOEGY" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. R. F. THEIS" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO OBJECT = DSREFINFO REFERENCE_KEY_ID = BRACEETAL1990 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF VENUS" JOURNAL_NAME = "JOURNAL OF GEOPHYSICAL RESEARCH" PUBLICATION_DATE = 1990 REFERENCE_DESC = " Brace, L. H., R. F. Theis, and J. D. Mihalov, 'The Response of the Venus Nightside Ionosphere and Ionotail to Solar EUV and Solar Wind Dynamic Pressure', J. Geophys. Res., 95, 4075, 1990." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. L. H. BRACE" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. J. D. MIHALOV" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. R. F. THEIS" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO OBJECT = DSREFINFO REFERENCE_KEY_ID = ELPHICETAL1984 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF VENUS" JOURNAL_NAME = "GEOPHYSICAL RESEARCH LETTERS" PUBLICATION_DATE = 1984 REFERENCE_DESC = " Elphic, R.C., L. H. Brace, R. F. Theis, and C. T. Russell, 'Venus Dayside Ionosphere Conditions: Effects of magnetic field and solar EUV flux', Geophys. Res. Lett., 11, 124, 1984." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. R. C. ELPHIC" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. L. H. BRACE" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. R. F. THEIS" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. C. T. RUSSELL" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO OBJECT = DSREFINFO REFERENCE_KEY_ID = KREHBIELETAL1980 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "LANGMUIR PROBES" JOURNAL_NAME = "IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING" PUBLICATION_DATE = 1980 REFERENCE_DESC = " Krehbiel, J. P., L. H. Brace, J. R. Cutler, W. H. Pinkus, and R. B. Kaplan, 'Pioneer Venus Orbiter Electron Temperature Probe', IEEE Transactions on Geoscience and Remote Sensing, GE-18, 49, 1980." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. J. P. KREHBIEL" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. L. H. BRACE" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. J. R. CUTLER" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. W. H. PINKUS" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. R. B. KAPLAN" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO OBJECT = DSREFINFO REFERENCE_KEY_ID = MAHAJANETAL1990 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF VENUS" JOURNAL_NAME = "JOURNAL OF GEOPHYSICAL RESEARCH" PUBLICATION_DATE = 1990 REFERENCE_DESC = " Mahajan, K. K, W. T. Kasprzak, L. H. Brace, H. B. Niemann, and W. R. Hoegy, 'Response of the Venus Exospheric Temperature Measured by Neutral Mass Spectrometer to the So lar EUV Measured by Langmuir Probe on the Pioneer Venus Orbiter', J. Geophys. Res., 95, 1091, 1990." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. K. K. MAHAJAN" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. W. T. KASPRZAK" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. L. H. BRACE" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. H. B. NIEMANN" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. W. R. HOEGY" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO OBJECT = DSREFINFO REFERENCE_KEY_ID = RUSSELLETAL1988 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF VENUS" JOURNAL_NAME = "JOURNAL OF GEOPHYSICAL RESEARCH" PUBLICATION_DATE = 1988 REFERENCE_DESC = " Russell, C. T., E. Chou, J. G. Luhmann, P. Gazis, L. H. Brace, and W. R. Hoegy, 'Solar and interplanetary control of the location of the Venus bow shock', J. Geophysic. Res ., 93, 5461, 1988." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "C. T. RUSSELL" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. T. E. CHOU" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. J. G. LUHMANN" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. P. GAZIS" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. L. H. BRACE" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. W. R. HOEGY" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO OBJECT = DSREFINFO REFERENCE_KEY_ID = THEISETAL1980 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF VENUS" JOURNAL_NAME = "ADVANCES IN SPACE RESEARCH" PUBLICATION_DATE = 1980 REFERENCE_DESC = " Theis, R. F., L. H. Brace, K. H. Schatten, C. T. Russell, J. A. Slavin, J. A. Wolf, 'The Venus ionosphere as an obstacle to the solar wind', Advances in Space Research, 1, 47, 1980." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. R. F. THEIS" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. L. H. BRACE" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. K. H. SCHATTEN" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "C. T. RUSSELL" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. J. A. SLAVIN" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. J. A. WOLF" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO OBJECT = DSREFINFO REFERENCE_KEY_ID = THEISETAL1984 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF VENUS" JOURNAL_NAME = "JOURNAL OF GEOPHYSICAL RESEARCH" PUBLICATION_DATE = 1984 REFERENCE_DESC = " Theis, R. F., L. H. Brace, R. C. Elphic, and H. G. Mayr, 'New empirical models of the electron temperature and density of the Venus ionosphere, with applications to transterminator flow', J. Geophys. Res., 89, 1477, 1984." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. R. F. THEIS" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. L. H. BRACE" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. R. C. ELPHIC" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. H. G. MAYR" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO END_OBJECT = SCDATASET ================================================================================ /******************** DATASET TEMPLATE ****************************************/ /* Template: Spacecraft Data Set Template Rev: 19890121 */ /* Note: The following templates form part of a standard set */ /* for the submission of a single dataset to the PDS. */ /* Hierarchy: SCDATASET */ /* DATASETINFO */ /* DATASETTARG */ /* DSPARMINFO */ /* SCDSHOST */ /* DSREFINFO */ /* REFERENCE */ /* REFAUTHORS */ OBJECT = SCDATASET DATA_SET_ID = "PVO-V-OETP-3-HIRESELECTRONS-V1.0" OBJECT = DATASETINFO DATA_SET_NAME = "PVO VENUS ELECT TEMP PROBE CALIB HIGH RES ELECTRONS VER 1.0" DATA_SET_COLLECTION_MEMBER_FLG = N START_TIME = "UNK" STOP_TIME = "UNK" NATIVE_START_TIME = UNK NATIVE_STOP_TIME = UNK DATA_OBJECT_TYPE = TIME_SERIES DATA_SET_RELEASE_DATE = 1993-10-01 PROCESSING_LEVEL_ID = 3 PRODUCER_FULL_NAME = "DR. ROBERT F. THEIS" PRODUCER_INSTITUTION_NAME = "GODDARD SPACE FLIGHT CENTER" SOFTWARE_FLAG = N DETAILED_CATALOG_FLAG = N PROCESSING_START_TIME = UNK PROCESSING_STOP_TIME = UNK DATA_SET_DESC = " The High Resolution Ne File. These data are based on measurements of the electron saturation current or the ion saturation current taken from as many voltampere curves as the telemetry data rate permitted. Since Ne is assumed equal to Ni everywhere in the ionosphere, either can be used as a measure of Ne. The ion current is used at high densities (Ni > 4x104cm-3) and the electron current is used at lower densities. Typically, 4 to 8 high resolution density samples are obtained in the interval between recovered voltampere curves, although this ratio is bit rate dependent. This provides Ne and Ni measurements at much smaller intervals than is possible from the voltampere curves themselves. High resolution measurements are typically available at 2 to 8 second intervals depending upon the telemetry rate available to the OETP at the time. The High Resolution file provides measurements of Ne (or Ni) within 30 minutes either side of periapsis at somewhat higher resolution than is possible from the voltampere curves. However, these measurements are less accurate when the spacecraft is outside the ionosphere, where Ne is typically well below 100 cm-3. In sunlight, spacecraft photoelectron densities at the radial probe location are of the order of 30-50 cm-3. In darkness, the Ne measurements can be made down to densities of about 2 cm-3 because the pe background is absent. However, the measurements made in the Venus umbra are often degraded at low densities because of the presence of hot electrons that charge the spacecraft to potentials that lie beyond the range of the OETP sweep voltage. This makes it impossible to drive the probe positive with respect to the plasma potential. In addition, deBye shielding causes the probe to become enveloped in the ion sheath of the spacecraft at very low densities, further reducing its access to the ambient ionospheric plasma. Empirically derived corrections for this effect have been applied to the high resolution data in order to provide at least a lower limit of Ne, but the errors could exceed a factor of 2 at densities below 10 cm-3. This correction does not allow Ne to be less than 2 cm-3. When the electron current at maximum positive voltage is less than a certain very low value an Ne value of 2 cm-3 is entered in the High Resolution file simply to serve as an upper limit on Ne, and to show that data were actually being taken. In summary, the high resolution Ne measurements provide about a factor of 8 higher resolution than the UADS file whose resolution is limited by the recovery rate of raw voltampere curves. Therefore the high resolution data better resolve such small scale features as the ionopause and the plasma clouds often found above the ionopause. Also, the UADS densities often stop somewhere within the ionopause density gradient, so this feature can best be resolved using the High Resolution data. However, certain artifacts have not been removed from the data, so one must be careful not of over-interpret them. (See section on accuracy)" /***************************************************************************/ CONFIDENCE_LEVEL_NOTE = " In general, the high resolution Ne measurements have a lower absolute accuracy than the UADS (voltampere curve) measurements because factors such as the spacecraft potential and Te are not available to calculate Ne more precisely. To reduce such errors in the high resolution data, they are normalized to the voltampere curve measurements. This normalization is entirely different from the Ne-Ni normalization employed in deriving the UADS data. Another source of error in the High Resolution Ne measurements is the jump discontinuities that occur when the spacecraft passes from sunlight to shadow. An abrupt change in spacecraft potential occurs at that point, and this changes the probe voltage which is referenced to the spacecraft. The Ne measurements cannot easily be corrected for this change because they are not based on voltampere curves but measurements at a fixed positive potential. Therefore a discontinuity may occur in Ne at the sunlight-shadow boundary if Ne is sufficiently low that spacecraft photoelectron emission affects the spacecraft potential. The precision of the high resolution data is probably somewhat better than that of the UADS data because the latter may suffer from the effects of volt ampere curve distortion due to small scale density variations and spin effects which do not show up in the single point samples used in the high resolution measurements. This feature makes the high resolution data more valuable in resolving small scale, and small amplitude plasma structure." /***************************************************************************/ END_OBJECT = DATASETINFO OBJECT = DATASETTARG TARGET_NAME = VENUS END_OBJECT = DATASETTARG OBJECT = DSPARMINFO SAMPLING_PARAMETER_NAME = TIME SAMPLING_PARAMETER_RESOLUTION = "N/A" MINIMUM_SAMPLING_PARAMETER = "N/A" MAXIMUM_SAMPLING_PARAMETER = "N/A" SAMPLING_PARAMETER_INTERVAL = "N/A" MINIMUM_AVAILABLE_SAMPLING_INT = 2 SAMPLING_PARAMETER_UNIT = SECOND DATA_SET_PARAMETER_NAME = "ELECTRON DENSITY" NOISE_LEVEL = 2 DATA_SET_PARAMETER_UNIT = "CM**-3" END_OBJECT = DSPARMINFO OBJECT = DSPARMINFO SAMPLING_PARAMETER_NAME = TIME SAMPLING_PARAMETER_RESOLUTION = "N/A" MINIMUM_SAMPLING_PARAMETER = "N/A" MAXIMUM_SAMPLING_PARAMETER = "N/A" SAMPLING_PARAMETER_INTERVAL = "N/A" MINIMUM_AVAILABLE_SAMPLING_INT = 2 SAMPLING_PARAMETER_UNIT = SECOND DATA_SET_PARAMETER_NAME = "ELECTRON TEMPERATURE" NOISE_LEVEL = UNK DATA_SET_PARAMETER_UNIT = "DEGREES KELVIN" END_OBJECT = DSPARMINFO OBJECT = DSPARMINFO SAMPLING_PARAMETER_NAME = TIME SAMPLING_PARAMETER_RESOLUTION = "N/A" MINIMUM_SAMPLING_PARAMETER = "N/A" MAXIMUM_SAMPLING_PARAMETER = "N/A" SAMPLING_PARAMETER_INTERVAL = "N/A" MINIMUM_AVAILABLE_SAMPLING_INT = 2 SAMPLING_PARAMETER_UNIT = SECOND DATA_SET_PARAMETER_NAME = "SPACECRAFT POTENTIAL" NOISE_LEVEL = UNK DATA_SET_PARAMETER_UNIT = "VOLTS" END_OBJECT = DSPARMINFO OBJECT = SCDSHOST INSTRUMENT_HOST_ID = PVO INSTRUMENT_ID = OETP END_OBJECT = SCDSHOST OBJECT = DSREFINFO REFERENCE_KEY_ID = ALEXANDERETAL1985 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF VENUS" JOURNAL_NAME = "GEOPHYSICAL RESEARCH LETTERS" PUBLICATION_DATE = 1985 REFERENCE_DESC = " Alexander, C. J., C. T. Russell, Solar cycle dependence of the location of the Venus bow shock, Geophys. Res. Lett., 12, 369, 1985." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "C. J. ALEXANDER" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "C. T. RUSSELL" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO OBJECT = DSREFINFO REFERENCE_KEY_ID = BRACEETAL1987 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF VENUS" JOURNAL_NAME = "JOURNAL OF GEOPHYSICAL RESEARCH" PUBLICATION_DATE = 1987 REFERENCE_DESC = " Brace, L. H., W. T. Kasprzak, H. A. Taylor, Jr., R. F. Theis, C. T. Russell, A. Barnes, J. D. Mihalov, and D. M. Hunten, 'The ionotail of Venus: Its configuration and evidence for ion escape, J. Geophys. Res., 92, 15, 1987." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. L. H. BRACE" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. W. T. KASPRZAK" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. H. A. TAYLOR JR." END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. R. F. THEIS" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. C. T. RUSSELL" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. A. BARNES" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. J. D. MIHALOV" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. D. M. HUNTEN" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO OBJECT = DSREFINFO REFERENCE_KEY_ID = BRACEETAL1988 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF VENUS" JOURNAL_NAME = "JOURNAL OF GEOPHYSICAL RESEARCH" PUBLICATION_DATE = 1988 REFERENCE_DESC = " Brace, L. H., W. R. Hoegy, and R. F. Theis, 'Solar EUV measurements at Venus based on photoelectron emission from the Pioneer Venus Langmuir probe', J. Geophys. Res., 93, 7282, 1988." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. L. H. BRACE" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. W. R. HOEGY" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. R. F. THEIS" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO OBJECT = DSREFINFO REFERENCE_KEY_ID = BRACEETAL1990 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF VENUS" JOURNAL_NAME = "JOURNAL OF GEOPHYSICAL RESEARCH" PUBLICATION_DATE = 1990 REFERENCE_DESC = " Brace, L. H., R. F. Theis, and J. D. Mihalov, 'The Response of the Venus Nightside Ionosphere and Ionotail to Solar EUV and Solar Wind Dynamic Pressure', J. Geophys. Res., 95, 4075, 1990." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. L. H. BRACE" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. J. D. MIHALOV" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. R. F. THEIS" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO OBJECT = DSREFINFO REFERENCE_KEY_ID = ELPHICETAL1984 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF VENUS" JOURNAL_NAME = "GEOPHYSICAL RESEARCH LETTERS" PUBLICATION_DATE = 1984 REFERENCE_DESC = " Elphic, R.C., L. H. Brace, R. F. Theis, and C. T. Russell, 'Venus Dayside Ionosphere Conditions: Effects of magnetic field and solar EUV flux', Geophys. Res. Lett., 11, 124, 1984." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. R. C. ELPHIC" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. L. H. BRACE" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. R. F. THEIS" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. C. T. RUSSELL" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO OBJECT = DSREFINFO REFERENCE_KEY_ID = KREHBIELETAL1980 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "LANGMUIR PROBES" JOURNAL_NAME = "IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING" PUBLICATION_DATE = 1980 REFERENCE_DESC = " Krehbiel, J. P., L. H. Brace, J. R. Cutler, W. H. Pinkus, and R. B. Kaplan, 'Pioneer Venus Orbiter Electron Temperature Probe', IEEE Transactions on Geoscience and Remote Sensing, GE-18, 49, 1980." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. J. P. KREHBIEL" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. L. H. BRACE" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. J. R. CUTLER" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. W. H. PINKUS" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. R. B. KAPLAN" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO OBJECT = DSREFINFO REFERENCE_KEY_ID = MAHAJANETAL1990 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF VENUS" JOURNAL_NAME = "JOURNAL OF GEOPHYSICAL RESEARCH" PUBLICATION_DATE = 1990 REFERENCE_DESC = " Mahajan, K. K, W. T. Kasprzak, L. H. Brace, H. B. Niemann, and W. R. Hoegy, 'Response of the Venus Exospheric Temperature Measured by Neutral Mass Spectrometer to the So lar EUV Measured by Langmuir Probe on the Pioneer Venus Orbiter', J. Geophys. Res., 95, 1091, 1990." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. K. K. MAHAJAN" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. W. T. KASPRZAK" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. L. H. BRACE" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. H. B. NIEMANN" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. W. R. HOEGY" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO OBJECT = DSREFINFO REFERENCE_KEY_ID = RUSSELLETAL1988 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF VENUS" JOURNAL_NAME = "JOURNAL OF GEOPHYSICAL RESEARCH" PUBLICATION_DATE = 1988 REFERENCE_DESC = " Russell, C. T., E. Chou, J. G. Luhmann, P. Gazis, L. H. Brace, and W. R. Hoegy, 'Solar and interplanetary control of the location of the Venus bow shock', J. Geophysic. Res ., 93, 5461, 1988." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "C. T. RUSSELL" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. T. E. CHOU" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. J. G. LUHMANN" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. P. GAZIS" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. L. H. BRACE" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. W. R. HOEGY" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO OBJECT = DSREFINFO REFERENCE_KEY_ID = THEISETAL1980 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF VENUS" JOURNAL_NAME = "ADVANCES IN SPACE RESEARCH" PUBLICATION_DATE = 1980 REFERENCE_DESC = " Theis, R. F., L. H. Brace, K. H. Schatten, C. T. Russell, J. A. Slavin, J. A. Wolf, 'The Venus ionosphere as an obstacle to the solar wind', Advances in Space Research, 1, 47, 1980." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. R. F. THEIS" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. L. H. BRACE" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. K. H. SCHATTEN" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "C. T. RUSSELL" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. J. A. SLAVIN" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. J. A. WOLF" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO OBJECT = DSREFINFO REFERENCE_KEY_ID = THEISETAL1984 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF VENUS" JOURNAL_NAME = "JOURNAL OF GEOPHYSICAL RESEARCH" PUBLICATION_DATE = 1984 REFERENCE_DESC = " Theis, R. F., L. H. Brace, R. C. Elphic, and H. G. Mayr, 'New empirical models of the electron temperature and density of the Venus ionosphere, with applications to transterminator flow', J. Geophys. Res., 89, 1477, 1984." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. R. F. THEIS" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. L. H. BRACE" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. R. C. ELPHIC" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. H. G. MAYR" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO END_OBJECT = SCDATASET ================================================================================ /******************** DATASET TEMPLATE ****************************************/ /* Template: Spacecraft Data Set Template Rev: 19890121 */ /* Note: The following templates form part of a standard set */ /* for the submission of a single dataset to the PDS. */ /* Hierarchy: SCDATASET */ /* DATASETINFO */ /* DATASETTARG */ /* DSPARMINFO */ /* SCDSHOST */ /* DSREFINFO */ /* REFERENCE */ /* REFAUTHORS */ OBJECT = SCDATASET DATA_SET_ID = "PVO-V-OETP-5-IONOPAUSELOCATION-V1.0" OBJECT = DATASETINFO DATA_SET_NAME = "PVO VENUS ELECT TEMP PROBE DERVD IONOPAUSE LOCATION VER 1.0" DATA_SET_COLLECTION_MEMBER_FLG = N START_TIME = "UNK" STOP_TIME = "UNK" NATIVE_START_TIME = UNK NATIVE_STOP_TIME = UNK DATA_OBJECT_TYPE = TABLE DATA_SET_RELEASE_DATE = 1993-10-01 PROCESSING_LEVEL_ID = 5 PRODUCER_FULL_NAME = "DR. ROBERT F. THEIS" PRODUCER_INSTITUTION_NAME = "GODDARD SPACE FLIGHT CENTER" SOFTWARE_FLAG = Y DETAILED_CATALOG_FLAG = N PROCESSING_START_TIME = UNK PROCESSING_STOP_TIME = UNK DATA_SET_DESC = " The Ionopause File. This file gives the orbit-by-orbit times and locations of the ionopause crossings, which are evident as sharp gradients in Ne at the top of the ionosphere. (These crossings always occur within 30 minutes of periapsis, so they may be seen in the High Resolution Ne files). The ionopause and bow shock crossing times and locations are easily identified in the high resolution Ne measurements (Theis et al., 1980). These files contain the UT, altitude, latitude, SZA and local time of each crossing. On the dayside, the ionopause is taken (somewhat arbitrarily) at the level in the steep gradient of the ionopause where Ne = 1x102 cm-3. On the nightside, the ionopause is selected at somewhat lower densities because the absence of spacecraft photoelectrons lowers the Ne measurement threshold. In both cases, the intent is to identify the ionopause as the point where the first rise of Ne above the background density occurs. Of course, the ionopause itself is not a point but is the extend region in which the ionopause density gradient occurs." /****************************************************************************/ CONFIDENCE_LEVEL_NOTE = " The ionopause location is selected at that point in the steep gradient of the ionopause where Ne crosses through the level of 1x102 cm-3. When the spacecraft is in darkness, the pe background is absent and the ionospheric Ne is also much lower, so the ionopause is identified as the first rise in Ne above whatever background is present. The ionopause is identified by a human operator who views each high resolution Ne pass plot on an interactive computer terminal. He selects the ionopause somewhat subjectively as the time of the first rise above the background Ne, which may consist of magnetosheath plasma or photoelectrons. The 40 minute pass plots used for this purpose provide only a 5-10 second accuracy in the crossing times. When irregularities or waviness in the ionopause produce several ionopause crossings, the outer most crossing is the only one identified." /****************************************************************************/ END_OBJECT = DATASETINFO OBJECT = DATASETTARG TARGET_NAME = VENUS END_OBJECT = DATASETTARG OBJECT = DSPARMINFO SAMPLING_PARAMETER_NAME = TIME SAMPLING_PARAMETER_RESOLUTION = "N/A" MINIMUM_SAMPLING_PARAMETER = "N/A" MAXIMUM_SAMPLING_PARAMETER = "N/A" SAMPLING_PARAMETER_INTERVAL = 12 MINIMUM_AVAILABLE_SAMPLING_INT = "N/A" SAMPLING_PARAMETER_UNIT = SECOND DATA_SET_PARAMETER_NAME = "POSITION VECTOR" NOISE_LEVEL = "N/A" DATA_SET_PARAMETER_UNIT = "N/A" END_OBJECT = DSPARMINFO OBJECT = SCDSHOST INSTRUMENT_HOST_ID = PVO INSTRUMENT_ID = OETP END_OBJECT = SCDSHOST OBJECT = DSREFINFO REFERENCE_KEY_ID = ALEXANDERETAL1985 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF VENUS" JOURNAL_NAME = "GEOPHYSICAL RESEARCH LETTERS" PUBLICATION_DATE = 1985 REFERENCE_DESC = " Alexander, C. J., C. T. Russell, Solar cycle dependence of the location of the Venus bow shock, Geophys. Res. Lett., 12, 369, 1985." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "C. J. ALEXANDER" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "C. T. RUSSELL" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO OBJECT = DSREFINFO REFERENCE_KEY_ID = BRACEETAL1987 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF VENUS" JOURNAL_NAME = "JOURNAL OF GEOPHYSICAL RESEARCH" PUBLICATION_DATE = 1987 REFERENCE_DESC = " Brace, L. H., W. T. Kasprzak, H. A. Taylor, Jr., R. F. Theis, C. T. Russell, A. Barnes, J. D. Mihalov, and D. M. Hunten, 'The ionotail of Venus: Its configuration and evidence for ion escape, J. Geophys. Res., 92, 15, 1987." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. L. H. BRACE" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. W. T. KASPRZAK" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. H. A. TAYLOR JR." END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. R. F. THEIS" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. C. T. RUSSELL" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. A. BARNES" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. J. D. MIHALOV" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. D. M. HUNTEN" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO OBJECT = DSREFINFO REFERENCE_KEY_ID = BRACEETAL1988 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF VENUS" JOURNAL_NAME = "JOURNAL OF GEOPHYSICAL RESEARCH" PUBLICATION_DATE = 1988 REFERENCE_DESC = " Brace, L. H., W. R. Hoegy, and R. F. Theis, 'Solar EUV measurements at Venus based on photoelectron emission from the Pioneer Venus Langmuir probe', J. Geophys. Res., 93, 7282, 1988." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. L. H. BRACE" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. W. R. HOEGY" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. R. F. THEIS" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO OBJECT = DSREFINFO REFERENCE_KEY_ID = BRACEETAL1990 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF VENUS" JOURNAL_NAME = "JOURNAL OF GEOPHYSICAL RESEARCH" PUBLICATION_DATE = 1990 REFERENCE_DESC = " Brace, L. H., R. F. Theis, and J. D. Mihalov, 'The Response of the Venus Nightside Ionosphere and Ionotail to Solar EUV and Solar Wind Dynamic Pressure', J. Geophys. Res., 95, 4075, 1990." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. L. H. BRACE" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. J. D. MIHALOV" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. R. F. THEIS" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO OBJECT = DSREFINFO REFERENCE_KEY_ID = ELPHICETAL1984 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF VENUS" JOURNAL_NAME = "GEOPHYSICAL RESEARCH LETTERS" PUBLICATION_DATE = 1984 REFERENCE_DESC = " Elphic, R.C., L. H. Brace, R. F. Theis, and C. T. Russell, 'Venus Dayside Ionosphere Conditions: Effects of magnetic field and solar EUV flux', Geophys. Res. Lett., 11, 124, 1984." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. R. C. ELPHIC" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. L. H. BRACE" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. R. F. THEIS" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. C. T. RUSSELL" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO OBJECT = DSREFINFO REFERENCE_KEY_ID = KREHBIELETAL1980 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "LANGMUIR PROBES" JOURNAL_NAME = "IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING" PUBLICATION_DATE = 1980 REFERENCE_DESC = " Krehbiel, J. P., L. H. Brace, J. R. Cutler, W. H. Pinkus, and R. B. Kaplan, 'Pioneer Venus Orbiter Electron Temperature Probe', IEEE Transactions on Geoscience and Remote Sensing, GE-18, 49, 1980." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. J. P. KREHBIEL" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. L. H. BRACE" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. J. R. CUTLER" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. W. H. PINKUS" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. R. B. KAPLAN" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO OBJECT = DSREFINFO REFERENCE_KEY_ID = MAHAJANETAL1990 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF VENUS" JOURNAL_NAME = "JOURNAL OF GEOPHYSICAL RESEARCH" PUBLICATION_DATE = 1990 REFERENCE_DESC = " Mahajan, K. K, W. T. Kasprzak, L. H. Brace, H. B. Niemann, and W. R. Hoegy, 'Response of the Venus Exospheric Temperature Measured by Neutral Mass Spectrometer to the So lar EUV Measured by Langmuir Probe on the Pioneer Venus Orbiter', J. Geophys. Res., 95, 1091, 1990." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. K. K. MAHAJAN" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. W. T. KASPRZAK" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. L. H. BRACE" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. H. B. NIEMANN" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. W. R. HOEGY" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO OBJECT = DSREFINFO REFERENCE_KEY_ID = RUSSELLETAL1988 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF VENUS" JOURNAL_NAME = "JOURNAL OF GEOPHYSICAL RESEARCH" PUBLICATION_DATE = 1988 REFERENCE_DESC = " Russell, C. T., E. Chou, J. G. Luhmann, P. Gazis, L. H. Brace, and W. R. Hoegy, 'Solar and interplanetary control of the location of the Venus bow shock', J. Geophysic. Res ., 93, 5461, 1988." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "C. T. RUSSELL" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. T. E. CHOU" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. J. G. LUHMANN" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. P. GAZIS" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. L. H. BRACE" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. W. R. HOEGY" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO OBJECT = DSREFINFO REFERENCE_KEY_ID = THEISETAL1980 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF VENUS" JOURNAL_NAME = "ADVANCES IN SPACE RESEARCH" PUBLICATION_DATE = 1980 REFERENCE_DESC = " Theis, R. F., L. H. Brace, K. H. Schatten, C. T. Russell, J. A. Slavin, J. A. Wolf, 'The Venus ionosphere as an obstacle to the solar wind', Advances in Space Research, 1, 47, 1980." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. R. F. THEIS" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. L. H. BRACE" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. K. H. SCHATTEN" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "C. T. RUSSELL" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. J. A. SLAVIN" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. J. A. WOLF" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO OBJECT = DSREFINFO REFERENCE_KEY_ID = THEISETAL1984 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF VENUS" JOURNAL_NAME = "JOURNAL OF GEOPHYSICAL RESEARCH" PUBLICATION_DATE = 1984 REFERENCE_DESC = " Theis, R. F., L. H. Brace, R. C. Elphic, and H. G. Mayr, 'New empirical models of the electron temperature and density of the Venus ionosphere, with applications to transterminator flow', J. Geophys. Res., 89, 1477, 1984." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. R. F. THEIS" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. L. H. BRACE" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. R. C. ELPHIC" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. H. G. MAYR" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO END_OBJECT = SCDATASET ================================================================================ /******************** DATASET TEMPLATE ****************************************/ /* Template: Spacecraft Data Set Template Rev: 19890121 */ /* Note: The following templates form part of a standard set */ /* for the submission of a single dataset to the PDS. */ /* Hierarchy: SCDATASET */ /* DATASETINFO */ /* DATASETTARG */ /* DSPARMINFO */ /* SCDSHOST */ /* DSREFINFO */ /* REFERENCE */ /* REFAUTHORS */ OBJECT = SCDATASET DATA_SET_ID = "PVO-V-OETP-4-SOLAREUV-24HRAVG-V1.0" OBJECT = DATASETINFO DATA_SET_NAME = "PVO VENUS ELECT TMP PROBE RESAMP SOLAR EUV 24 HR AVG VER 1.0" DATA_SET_COLLECTION_MEMBER_FLG = N START_TIME = "UNK" STOP_TIME = "UNK" NATIVE_START_TIME = UNK NATIVE_STOP_TIME = UNK DATA_OBJECT_TYPE = TABLE DATA_SET_RELEASE_DATE = 1993-10-01 PROCESSING_LEVEL_ID = 5 PRODUCER_FULL_NAME = "DR. ROBERT F. THEIS" PRODUCER_INSTITUTION_NAME = "GODDARD SPACE FLIGHT CENTER" SOFTWARE_FLAG = Y DETAILED_CATALOG_FLAG = N PROCESSING_START_TIME = UNK PROCESSING_STOP_TIME = UNK DATA_SET_DESC = " The Solar EUV Daily Values File. This file gives the magnitude of the photoemission current from the radial probe, Ipe, (in units of 10-9 amps). Ipe dominates the ion current measurements outside the Venusian ionosphere, making possible the serendipitous measurement of the total solar EUV flux. The latter is an important parameter because solar EUV is the main source of ionization and heating for the Venusian thermosphere and ionosphere. The method is discussed by Brace et al., (1988). The pe current measurements are taken just before PVO leaves the solar wind and enters the magnetosheath (usually an hour or two before periapsis). This approach provides the solar EUV flux that the Venus thermosphere received just before the periapsis measurements. The maximum value of the spin modulated Ipe is taken because it corresponds to a probe orientation perpendicular to the Sun when the maximum area of the probe is exposed to the Sun. Ipe is proportional to the intensity of the ionizing component of solar radiation, so it is possible to derive the total solar EUV (and far UV) flux. Ly alpha contributes approximately half of the Ipe while nearly all of the rest is produced by radiation between 200 A and 1200 A which ionizes, excites and dissociates thermospheric neutrals. This file contains the daily average value of the photoelectron emission current, Ipe, from the radial probe, usually measured about 1 hr before periapsis. The Ipe values are given in units of 10-9 amperes. The data cover the interval from 1979 through early 1992 when periapsis got low enough to cause photoelectric yield changes that have not been fully resolved and corrected for appropriately. The data provided cover orbits 1 to 4800. After orbit 4800, when PVO began to enter the atmosphere, the Langmuir probe could no longer be kept clean, and as a result the yield changed For further details, contact Walt Hoegy at GSFC code 914, (301) 286-3837 or email hoegy@mite.gsfc.nasa.gov. The daily Ipe measurements can be converted into the total solar EUV flux (VEUV) using the following the equation given by Brace et al., (1988), VEUV = 1.53 x 1011 Ipe (photons/cm2/s) VEUV represents the total solar flux, weighted by the known wavelength- dependent yield of the collector. A standard Hinteregger solar EUV/UV spectrum is assumed to derive the coefficient, but the measurement is relatively insensitive to this assumption over the typical range of variations in the solar spectrum. The VEUV data have been useful in the study of solar EUV effects on the ion production and electron heating rates in the Venus ionosphere. VEUV variations have been correlated with changes in the density and temperature of the ionosphere (Elphic et al., 1984), the height of the bow shock (Alexander et al., 1985, Russell et al., 1988), and changes in the density and temperature of the thermosphere (Mahajan et al., 1990)." /***************************************************************************/ CONFIDENCE_LEVEL_NOTE = " The Ipe measurements themselves are made with an absolute accuracy of 1 to 2%, depending upon where the current falls within the decade range of the ranging electrometer. The absolute accuracy of the measurements is also limited by our knowledge of the photoelectric yield of the radial probe collector, and our assumption that a Hinteregger standard EUV/UV spectrum is correct. We estimate a 10% absolute accuracy in the total EUV flux and a 1 to 2% relative accuracy or precision provided by the accuracy of the current measurements themselves. See Brace et al.(1988) for details of the method." /***************************************************************************/ END_OBJECT = DATASETINFO OBJECT = DATASETTARG TARGET_NAME = VENUS END_OBJECT = DATASETTARG OBJECT = DSPARMINFO SAMPLING_PARAMETER_NAME = "N/A" SAMPLING_PARAMETER_RESOLUTION = "N/A" MINIMUM_SAMPLING_PARAMETER = "N/A" MAXIMUM_SAMPLING_PARAMETER = "N/A" SAMPLING_PARAMETER_INTERVAL = "N/A" MINIMUM_AVAILABLE_SAMPLING_INT = "N/A" SAMPLING_PARAMETER_UNIT = "N/A" DATA_SET_PARAMETER_NAME = "PHOTOELECTRON CURRENT" NOISE_LEVEL = UNK DATA_SET_PARAMETER_UNIT = "AMPERES / 10**9" END_OBJECT = DSPARMINFO OBJECT = SCDSHOST INSTRUMENT_HOST_ID = PVO INSTRUMENT_ID = OETP END_OBJECT = SCDSHOST OBJECT = DSREFINFO REFERENCE_KEY_ID = ALEXANDERETAL1985 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF VENUS" JOURNAL_NAME = "GEOPHYSICAL RESEARCH LETTERS" PUBLICATION_DATE = 1985 REFERENCE_DESC = " Alexander, C. J., C. T. Russell, Solar cycle dependence of the location of the Venus bow shock, Geophys. Res. Lett., 12, 369, 1985." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "C. J. ALEXANDER" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "C. T. RUSSELL" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO OBJECT = DSREFINFO REFERENCE_KEY_ID = BRACEETAL1987 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF VENUS" JOURNAL_NAME = "JOURNAL OF GEOPHYSICAL RESEARCH" PUBLICATION_DATE = 1987 REFERENCE_DESC = " Brace, L. H., W. T. Kasprzak, H. A. Taylor, Jr., R. F. Theis, C. T. Russell, A. Barnes, J. D. Mihalov, and D. M. Hunten, 'The ionotail of Venus: Its configuration and evidence for ion escape, J. Geophys. Res., 92, 15, 1987." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. L. H. BRACE" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. W. T. KASPRZAK" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. H. A. TAYLOR JR." END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. R. F. THEIS" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. C. T. RUSSELL" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. A. BARNES" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. J. D. MIHALOV" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. D. M. HUNTEN" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO OBJECT = DSREFINFO REFERENCE_KEY_ID = BRACEETAL1988 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF VENUS" JOURNAL_NAME = "JOURNAL OF GEOPHYSICAL RESEARCH" PUBLICATION_DATE = 1988 REFERENCE_DESC = " Brace, L. H., W. R. Hoegy, and R. F. Theis, 'Solar EUV measurements at Venus based on photoelectron emission from the Pioneer Venus Langmuir probe', J. Geophys. Res., 93, 7282, 1988." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. L. H. BRACE" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. W. R. HOEGY" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. R. F. THEIS" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO OBJECT = DSREFINFO REFERENCE_KEY_ID = BRACEETAL1990 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF VENUS" JOURNAL_NAME = "JOURNAL OF GEOPHYSICAL RESEARCH" PUBLICATION_DATE = 1990 REFERENCE_DESC = " Brace, L. H., R. F. Theis, and J. D. Mihalov, 'The Response of the Venus Nightside Ionosphere and Ionotail to Solar EUV and Solar Wind Dynamic Pressure', J. Geophys. Res., 95, 4075, 1990." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. L. H. BRACE" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. J. D. MIHALOV" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. R. F. THEIS" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO OBJECT = DSREFINFO REFERENCE_KEY_ID = ELPHICETAL1984 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF VENUS" JOURNAL_NAME = "GEOPHYSICAL RESEARCH LETTERS" PUBLICATION_DATE = 1984 REFERENCE_DESC = " Elphic, R.C., L. H. Brace, R. F. Theis, and C. T. Russell, 'Venus Dayside Ionosphere Conditions: Effects of magnetic field and solar EUV flux', Geophys. Res. Lett., 11, 124, 1984." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. R. C. ELPHIC" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. L. H. BRACE" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. R. F. THEIS" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. C. T. RUSSELL" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO OBJECT = DSREFINFO REFERENCE_KEY_ID = KREHBIELETAL1980 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "LANGMUIR PROBES" JOURNAL_NAME = "IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING" PUBLICATION_DATE = 1980 REFERENCE_DESC = " Krehbiel, J. P., L. H. Brace, J. R. Cutler, W. H. Pinkus, and R. B. Kaplan, 'Pioneer Venus Orbiter Electron Temperature Probe', IEEE Transactions on Geoscience and Remote Sensing, GE-18, 49, 1980." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. J. P. KREHBIEL" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. L. H. BRACE" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. J. R. CUTLER" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. W. H. PINKUS" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. R. B. KAPLAN" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO OBJECT = DSREFINFO REFERENCE_KEY_ID = MAHAJANETAL1990 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF VENUS" JOURNAL_NAME = "JOURNAL OF GEOPHYSICAL RESEARCH" PUBLICATION_DATE = 1990 REFERENCE_DESC = " Mahajan, K. K, W. T. Kasprzak, L. H. Brace, H. B. Niemann, and W. R. Hoegy, 'Response of the Venus Exospheric Temperature Measured by Neutral Mass Spectrometer to the So lar EUV Measured by Langmuir Probe on the Pioneer Venus Orbiter', J. Geophys. Res., 95, 1091, 1990." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. K. K. MAHAJAN" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. W. T. KASPRZAK" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. L. H. BRACE" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. H. B. NIEMANN" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. W. R. HOEGY" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO OBJECT = DSREFINFO REFERENCE_KEY_ID = RUSSELLETAL1988 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF VENUS" JOURNAL_NAME = "JOURNAL OF GEOPHYSICAL RESEARCH" PUBLICATION_DATE = 1988 REFERENCE_DESC = " Russell, C. T., E. Chou, J. G. Luhmann, P. Gazis, L. H. Brace, and W. R. Hoegy, 'Solar and interplanetary control of the location of the Venus bow shock', J. Geophysic. Res ., 93, 5461, 1988." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "C. T. RUSSELL" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. T. E. CHOU" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. J. G. LUHMANN" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. P. GAZIS" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. L. H. BRACE" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. W. R. HOEGY" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO OBJECT = DSREFINFO REFERENCE_KEY_ID = THEISETAL1980 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF VENUS" JOURNAL_NAME = "ADVANCES IN SPACE RESEARCH" PUBLICATION_DATE = 1980 REFERENCE_DESC = " Theis, R. F., L. H. Brace, K. H. Schatten, C. T. Russell, J. A. Slavin, J. A. Wolf, 'The Venus ionosphere as an obstacle to the solar wind', Advances in Space Research, 1, 47, 1980." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. R. F. THEIS" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. L. H. BRACE" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. K. H. SCHATTEN" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "C. T. RUSSELL" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. J. A. SLAVIN" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. J. A. WOLF" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO OBJECT = DSREFINFO REFERENCE_KEY_ID = THEISETAL1984 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF VENUS" JOURNAL_NAME = "JOURNAL OF GEOPHYSICAL RESEARCH" PUBLICATION_DATE = 1984 REFERENCE_DESC = " Theis, R. F., L. H. Brace, R. C. Elphic, and H. G. Mayr, 'New empirical models of the electron temperature and density of the Venus ionosphere, with applications to transterminator flow', J. Geophys. Res., 89, 1477, 1984." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. R. F. THEIS" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. L. H. BRACE" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. R. C. ELPHIC" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. H. G. MAYR" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO END_OBJECT = SCDATASET ================================================================================ /******************** DATASET TEMPLATE ****************************************/ /* Template: Spacecraft Data Set Template Rev: 19890121 */ /* Note: The following templates form part of a standard set */ /* for the submission of a single dataset to the PDS. */ /* Hierarchy: SCDATASET */ /* DATASETINFO */ /* DATASETTARG */ /* DSPARMINFO */ /* SCDSHOST */ /* DSREFINFO */ /* REFERENCE */ /* REFAUTHORS */ OBJECT = SCDATASET DATA_SET_ID = "PVO-V-OETP-5-ELECTRONDENSITY-LORES-V1.0" OBJECT = DATASETINFO DATA_SET_NAME = "PVO VENUS ELECT TEMP PROBE DERVD ELECT DENS LOW RES VER 1.0" DATA_SET_COLLECTION_MEMBER_FLG = N START_TIME = 1978-12-05T15:07:34.817 STOP_TIME = "UNK" NATIVE_START_TIME = UNK NATIVE_STOP_TIME = UNK DATA_OBJECT_TYPE = TIME_SERIES DATA_SET_RELEASE_DATE = 1993-10-01 PROCESSING_LEVEL_ID = 4 PRODUCER_FULL_NAME = "DR. ROBERT THEIS" PRODUCER_INSTITUTION_NAME = "GODDARD SPACE FLIGHT CENTER" SOFTWARE_FLAG = Y DETAILED_CATALOG_FLAG = N PROCESSING_START_TIME = UNK PROCESSING_STOP_TIME = UNK DATA_SET_DESC = " This file gives the Ne, Te and Vs measurements derived by fitting the radial probe voltampere curves taken whenever PVO was within the ionosphere (ie., between the inbound and outbound ionopause crossings). Data from essentially every orbit in 1979 and 1980 included ionosphere transits. After the summer of 1980, however, periapsis could no longer be maintained at low altitudes, and it rose slowly. After April 1981 periapsis was above the altitude of the dayside ionopause, so the spacecraft encountered the ionosphere only in the terminator regions and on the nightside where the ionosphere extends to much higher altitudes. Dayside measurements again became available early in 1992 when periapsis returned to low enough altitudes. The PVO Entry period of between July and October 1992 provided only nightside periapsis data. During the intervening period (1981-91), only nightside UADS measurements in the high altitude (downstream) ionosphere were available. Note that High Resolution Ne data from the 1981-91 interval provide measurements in the dayside magnetosheath and in the solar wind, but these data have limited accuracy because of spacecraft photoelectron contributions. See Brace et al, 1988 (ref. 53) in the bibliography for further details on the interpretation of High Resolution measurements made outside the ionosphere. As noted earlier, the geophysical values are listed at 12 second intervals in the UADS. Each OETP entry represents a time-weighted average of those radial probe measurements taken within approximately 10 seconds of the UADS-assigned times. If no voltampere curves were recovered within that 20 second interval (this occurs at very low spacecraft telemetry rates), no UADS value is entered in that 12 second slot. The instrument actually takes voltampere curves at a rate of 120/minute, but telemetry rate limitations permit the recovery of raw voltampere curves at intervals between 4 to 32 seconds, depending upon the telemetry rate and spacecraft data format currently in use. The Ne values in the UADS file may actually be based on either the ion or electron current collected by the probe, depending upon the magnitude of the density at the time. The radial probe electron currents saturate the electrometer when Ne > 4x104 cm-3, so it is necessary to switch over to Ni measurements at that point. Since the ion currents are about a factor of 50 smaller, the Ni measurements can be made up to densities of about 2 x 106 cm-3, much greater than is present anywhere in the Venus ionosphere. We assume that Ni = Ne everywhere in the ionosphere, so either may be used to construct the UADS file. To minimize any discontinuity that may occur at the Ne/Ni switch-over point due to systematic measurement errors, Ne is normalized to Ni using a small universal correction factor. This factor is 0.7, and is based on comparisons of the overlapping Ne and Ni measurements from many individual orbits. There are good theoretical reasons to believe that the Ni measurements are inherently more accurate at densities exceeding 3 or 4x104 cm-3, so this normalization approach improves the accuracy of the Ne measurements. The Ni measurements become less accurate at lower densities because of uncertain changes in the ion composition, ion drift velocity, and a positive ion current component produced by photoelectrons (Ipe) leaving the probe. Ipe becomes comparable to the true ion currents at Ni of approximately 1x104cm-3. The pe currents produce a spin modulated signal that is modelled using measurements made in the solar wind just prior to the bow shock crossing where the ambient densities are too small to produce detectable ion currents. This spin modulated Ipe waveform, whose amplitude is different from orbit to orbit because of solar EUV variations, is subtracted from the net positive current measurements made in the subsequent ionospheric passage. This subtraction gives the true ion current which is directly convertible to Ni. The spin maximum Ipe for each orbit is also used to construct the solar EUV file, as is described later. Because of the low spatial resolution of the UADS, and the fact that only ionosphere data are included, this file is not the best source of information about the ionopause. Features such as the ionopause, and plasma clouds above the ionopause, are resolved better using the High Resolution Data File which is not restricted to measurements within the ionosphere." /****************************************************************************/ CONFIDENCE_LEVEL_NOTE = " The UADS data are based on operator-assisted voltampere curve fits. The absolute accuracy of the data depends primarily upon the accuracy of the Langmuir probe theory (Krehbiel, et al., 1980) and our success in avoiding the inclusion of data from curves that were obtained in situations in which the theory does not apply (e.g., probe in wake of the telemetry antenna, very low densities, pe contamination, spacecraft potential too negative, etc.). Where these effects have been avoided, the errors in Te should not exceed 5% when Ne exceeds 500 cm-3 in sunlight and about 30 cm-3 in darkness. However, Te errors may be larger in regions of great spatial structure where the plasma parameters change while they are being measured, or in regions where the electron energy distribution is nonmaxwellian or appears to have two temperatures. These conditions are often found in the nightside ionosphere and at the ionopause. In these cases, the curve-fitting is done so as to measure the temperature of the lower temperature component of the plasma. The curves would have to be refitted to obtain information on the higher temperature component. The accuracy of the Ne measurements is determined by the accuracy of the Ni measurements to which they are normalized by a fixed factor that was determined by comparisons at densities in the vicinity of 4 x 104 cm-3. Therefore the Ne accuracy is nominally 10%, but the error increases at low densities where pe background and/or spacecraft charging effects can be important, as described earlier. Ne is given in the UADS file for densities down to 2 cm-3 and Te for densities down to 10 cm-3, which are observed only in the nightside ionosphere and ionotail. The Ne error is expected to grow as the density approaches these limits, but the Te measurements are less subject to error at low densities because knowledge of Vs is not needed to obtain the temperature. In spite of the reduced accuracy, Ne measurements below 30 cm-3 are retained in the UADS file because they do reflect real variations that may be of interest even when their absolute accuracy may be uncertain by a factor of 2 or more. Examples include the detection of weak ionospheric tail rays and plasma clouds (Brace et al., 1987). The error in Ni is not expected to exceed 10% at densities above 4 x104 cm-3. Ne is used for densities below 4 x104 cm-3. As noted earlier, Ne is normalized to Ni at their overlap point to gain the greater inherent accuracy of the ion measurements. The normalization factor is based on the overlapping Ne and Ni measurements from many orbits, and the factor does not change throughout the mission. Therefore, small discontinuities in the density measurement may sometimes be seen at the crossover point if ionospheric conditions lead to unusual spacecraft potentials, ion compositions, or other factors that are assumed constant when adopting a fixed relationship between the ion and electron currents. We assume that the normalization factor remains constant over the full range of Ne, and this may not be correct." /****************************************************************************/ END_OBJECT = DATASETINFO OBJECT = DATASETTARG TARGET_NAME = VENUS END_OBJECT = DATASETTARG OBJECT = DSPARMINFO SAMPLING_PARAMETER_NAME = TIME SAMPLING_PARAMETER_RESOLUTION = "N/A" MINIMUM_SAMPLING_PARAMETER = "N/A" MAXIMUM_SAMPLING_PARAMETER = "N/A" SAMPLING_PARAMETER_INTERVAL = 12 MINIMUM_AVAILABLE_SAMPLING_INT = "N/A" SAMPLING_PARAMETER_UNIT = SECOND DATA_SET_PARAMETER_NAME = "ELECTRON DENSITY" NOISE_LEVEL = 2 DATA_SET_PARAMETER_UNIT = "CM**-3" END_OBJECT = DSPARMINFO OBJECT = DSPARMINFO SAMPLING_PARAMETER_NAME = TIME SAMPLING_PARAMETER_RESOLUTION = "N/A" MINIMUM_SAMPLING_PARAMETER = "N/A" MAXIMUM_SAMPLING_PARAMETER = "N/A" SAMPLING_PARAMETER_INTERVAL = 12 MINIMUM_AVAILABLE_SAMPLING_INT = "N/A" SAMPLING_PARAMETER_UNIT = SECOND DATA_SET_PARAMETER_NAME = "ELECTRON TEMPERATURE" NOISE_LEVEL = UNK DATA_SET_PARAMETER_UNIT = "DEGREES KELVIN" END_OBJECT = DSPARMINFO OBJECT = DSPARMINFO SAMPLING_PARAMETER_NAME = TIME SAMPLING_PARAMETER_RESOLUTION = "N/A" MINIMUM_SAMPLING_PARAMETER = "N/A" MAXIMUM_SAMPLING_PARAMETER = "N/A" SAMPLING_PARAMETER_INTERVAL = 12 MINIMUM_AVAILABLE_SAMPLING_INT = "N/A" SAMPLING_PARAMETER_UNIT = SECOND DATA_SET_PARAMETER_NAME = "SPACECRAFT POTENTIAL" NOISE_LEVEL = UNK DATA_SET_PARAMETER_UNIT = "VOLTS" END_OBJECT = DSPARMINFO OBJECT = SCDSHOST INSTRUMENT_HOST_ID = PVO INSTRUMENT_ID = OETP END_OBJECT = SCDSHOST OBJECT = DSREFINFO REFERENCE_KEY_ID = ALEXANDERETAL1985 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF VENUS" JOURNAL_NAME = "GEOPHYSICAL RESEARCH LETTERS" PUBLICATION_DATE = 1985 REFERENCE_DESC = " Alexander, C. J., C. T. Russell, Solar cycle dependence of the location of the Venus bow shock, Geophys. Res. Lett., 12, 369, 1985." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "C. J. ALEXANDER" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "C. T. RUSSELL" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO OBJECT = DSREFINFO REFERENCE_KEY_ID = BRACEETAL1987 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF VENUS" JOURNAL_NAME = "JOURNAL OF GEOPHYSICAL RESEARCH" PUBLICATION_DATE = 1987 REFERENCE_DESC = " Brace, L. H., W. T. Kasprzak, H. A. Taylor, Jr., R. F. Theis, C. T. Russell, A. Barnes, J. D. Mihalov, and D. M. Hunten, 'The ionotail of Venus: Its configuration and evidence for ion escape, J. Geophys. Res., 92, 15, 1987." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. L. H. BRACE" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. W. T. KASPRZAK" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. H. A. TAYLOR JR." END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. R. F. THEIS" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. C. T. RUSSELL" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. A. BARNES" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. J. D. MIHALOV" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. D. M. HUNTEN" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO OBJECT = DSREFINFO REFERENCE_KEY_ID = BRACEETAL1988 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF VENUS" JOURNAL_NAME = "JOURNAL OF GEOPHYSICAL RESEARCH" PUBLICATION_DATE = 1988 REFERENCE_DESC = " Brace, L. H., W. R. Hoegy, and R. F. Theis, 'Solar EUV measurements at Venus based on photoelectron emission from the Pioneer Venus Langmuir probe', J. Geophys. Res., 93, 7282, 1988." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. L. H. BRACE" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. W. R. HOEGY" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. R. F. THEIS" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO OBJECT = DSREFINFO REFERENCE_KEY_ID = BRACEETAL1990 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF VENUS" JOURNAL_NAME = "JOURNAL OF GEOPHYSICAL RESEARCH" PUBLICATION_DATE = 1990 REFERENCE_DESC = " Brace, L. H., R. F. Theis, and J. D. Mihalov, 'The Response of the Venus Nightside Ionosphere and Ionotail to Solar EUV and Solar Wind Dynamic Pressure', J. Geophys. Res., 95, 4075, 1990." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. L. H. BRACE" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. J. D. MIHALOV" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. R. F. THEIS" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO OBJECT = DSREFINFO REFERENCE_KEY_ID = ELPHICETAL1984 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF VENUS" JOURNAL_NAME = "GEOPHYSICAL RESEARCH LETTERS" PUBLICATION_DATE = 1984 REFERENCE_DESC = " Elphic, R.C., L. H. Brace, R. F. Theis, and C. T. Russell, 'Venus Dayside Ionosphere Conditions: Effects of magnetic field and solar EUV flux', Geophys. Res. Lett., 11, 124, 1984." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. R. C. ELPHIC" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. L. H. BRACE" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. R. F. THEIS" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. C. T. RUSSELL" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO OBJECT = DSREFINFO REFERENCE_KEY_ID = KREHBIELETAL1980 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "LANGMUIR PROBES" JOURNAL_NAME = "IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING" PUBLICATION_DATE = 1980 REFERENCE_DESC = " Krehbiel, J. P., L. H. Brace, J. R. Cutler, W. H. Pinkus, and R. B. Kaplan, 'Pioneer Venus Orbiter Electron Temperature Probe', IEEE Transactions on Geoscience and Remote Sensing, GE-18, 49, 1980." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. J. P. KREHBIEL" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. L. H. BRACE" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. J. R. CUTLER" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. W. H. PINKUS" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. R. B. KAPLAN" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO OBJECT = DSREFINFO REFERENCE_KEY_ID = MAHAJANETAL1990 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF VENUS" JOURNAL_NAME = "JOURNAL OF GEOPHYSICAL RESEARCH" PUBLICATION_DATE = 1990 REFERENCE_DESC = " Mahajan, K. K, W. T. Kasprzak, L. H. Brace, H. B. Niemann, and W. R. Hoegy, 'Response of the Venus Exospheric Temperature Measured by Neutral Mass Spectrometer to the So lar EUV Measured by Langmuir Probe on the Pioneer Venus Orbiter', J. Geophys. Res., 95, 1091, 1990." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. K. K. MAHAJAN" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. W. T. KASPRZAK" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. L. H. BRACE" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. H. B. NIEMANN" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. W. R. HOEGY" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO OBJECT = DSREFINFO REFERENCE_KEY_ID = RUSSELLETAL1988 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF VENUS" JOURNAL_NAME = "JOURNAL OF GEOPHYSICAL RESEARCH" PUBLICATION_DATE = 1988 REFERENCE_DESC = " Russell, C. T., E. Chou, J. G. Luhmann, P. Gazis, L. H. Brace, and W. R. Hoegy, 'Solar and interplanetary control of the location of the Venus bow shock', J. Geophysic. Res ., 93, 5461, 1988." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "C. T. RUSSELL" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. T. E. CHOU" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. J. G. LUHMANN" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. P. GAZIS" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. L. H. BRACE" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. W. R. HOEGY" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO OBJECT = DSREFINFO REFERENCE_KEY_ID = THEISETAL1980 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF VENUS" JOURNAL_NAME = "ADVANCES IN SPACE RESEARCH" PUBLICATION_DATE = 1980 REFERENCE_DESC = " Theis, R. F., L. H. Brace, K. H. Schatten, C. T. Russell, J. A. Slavin, J. A. Wolf, 'The Venus ionosphere as an obstacle to the solar wind', Advances in Space Research, 1, 47, 1980." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. R. F. THEIS" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. L. H. BRACE" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. K. H. SCHATTEN" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "C. T. RUSSELL" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. J. A. SLAVIN" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. J. A. WOLF" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO OBJECT = DSREFINFO REFERENCE_KEY_ID = THEISETAL1984 OBJECT = REFERENCE DOCUMENT_TOPIC_TYPE = "IONOSPHERE OF VENUS" JOURNAL_NAME = "JOURNAL OF GEOPHYSICAL RESEARCH" PUBLICATION_DATE = 1984 REFERENCE_DESC = " Theis, R. F., L. H. Brace, R. C. Elphic, and H. G. Mayr, 'New empirical models of the electron temperature and density of the Venus ionosphere, with applications to transterminator flow', J. Geophys. Res., 89, 1477, 1984." OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. R. F. THEIS" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. L. H. BRACE" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. R. C. ELPHIC" END_OBJECT = REFAUTHORS OBJECT = REFAUTHORS AUTHOR_FULL_NAME = "DR. H. G. MAYR" END_OBJECT = REFAUTHORS END_OBJECT = REFERENCE END_OBJECT = DSREFINFO END_OBJECT = SCDATASET ================================================================================ /******************************************************************************/ /* Template: Parameter Template Rev: 19890121 */ OBJECT = PARAMETER INSTRUMENT_HOST_ID = PVO DATA_SET_PARAMETER_NAME = "ELECTRON DENSITY" INSTRUMENT_PARAMETER_NAME = "ELECTRON CURRENT" IMPORTANT_INSTRUMENT_PARMS = 1 END_OBJECT = PARAMETER OBJECT = PARAMETER INSTRUMENT_HOST_ID = PVO DATA_SET_PARAMETER_NAME = "ELECTRON DENSITY" INSTRUMENT_PARAMETER_NAME = "ELECTRON RATE" IMPORTANT_INSTRUMENT_PARMS = 1 END_OBJECT = PARAMETER OBJECT = PARAMETER INSTRUMENT_HOST_ID = PVO DATA_SET_PARAMETER_NAME = "ELECTRON TEMPERATURE" INSTRUMENT_PARAMETER_NAME = "ELECTRON CURRENT" IMPORTANT_INSTRUMENT_PARMS = 1 END_OBJECT = PARAMETER OBJECT = PARAMETER INSTRUMENT_HOST_ID = PVO DATA_SET_PARAMETER_NAME = "SPACECRAFT TPOTENTIAL" INSTRUMENT_PARAMETER_NAME = "ELECTRON CURRENT" IMPORTANT_INSTRUMENT_PARMS = 1 END_OBJECT = PARAMETER OBJECT = PARAMETER INSTRUMENT_HOST_ID = PVO DATA_SET_PARAMETER_NAME = "POSITION VECTOR" INSTRUMENT_PARAMETER_NAME = "POSITION VECTOR" IMPORTANT_INSTRUMENT_PARMS = 1 END_OBJECT = PARAMETER ================================================================================ /*************** Electron Density Parm. Description Template ******************/ OBJECT = DSINSTPARMD DATA_SET_OR_INSTRUMENT_PARM_NM = 'ELECTRON DENSITY' DATA_SET_OR_INST_PARM_DESC = " A DERIVED PARAMETER EQUALING THE NUMBER OF ELECTRONS PER UNIT VOLUME OVER A SPECIFIED RANGE OF ELECTRON ENERGY. Different forms of electron density are derived distinguished by method of derivation (Maxwellian fit, method of moments) or by the some selection criteria (i.e., hot electron and cold electron density). In general, if more than one electron component is analyzed, either by moment or fit, a total density will be provided which is the sum of the electron densities. If the electron do not have a Maxwellian distribution the actual distribution can be represented as the sum of several Maxwellians, in which case the density of each Maxwellian is given." END_OBJECT = DSINSTPARMD ================================================================================ /*************** Electron Current Parm. Description Template ******************/ OBJECT = DSINSTPARMD DATA_SET_OR_INSTRUMENT_PARM_NM = 'ELECTRON CURRENT' DATA_SET_OR_INST_PARM_DESC = " A measured parameter equaling the rate at which negative charge is collected by a particle detector. The electrons contributing to this current may be restricted by energy. Electrons always have a charge of 1, so this quantity corresponds directly to the electron rate." END_OBJECT = DSINSTPARMD ================================================================================ /**************** Electron Rate Parameter Desc. Template ********************/ OBJECT = DSINSTPARMD DATA_SET_OR_INSTRUMENT_PARM_NM = "ELECTRON RATE" DATA_SET_OR_INST_PARM_DESC = " A measured parameter equaling the number of electrons hitting a particle detector per specified accumulation interval. The counted electrons may or may not be discriminated as to their energies (e.g. greater than E1, or between E1 and E2)." END_OBJECT = DSINSTPARMD ================================================================================ /*************** Electron Temperature Parm. Description Template **************/ OBJECT = DSINSTPARMD DATA_SET_OR_INSTRUMENT_PARM_NM = 'ELECTRON TEMPERATURE' DATA_SET_OR_INST_PARM_DESC = " A derived parameter giving an indication of the mean energy/electron, assuming the shape of the electron energy spectrum to be Maxwellian (i.e. highest entropy shape). Given that the electron energy spectrum is not exactly Maxwellian, the electron temperature can be defined integrally (whereby the mean energy obtained by integrating under the actual electron energy spectrum is set equal to the integral under a Maxwellian, where the temperature is a free parameter for which to solve), or differentially (whereby the slopes of the actually electron energy spectrum at various energies are matched to the slopes of a corresponding Maxwellian). The temperature parameter is often qualified with a range of applicable energies. temperatures can be angularly anisotropic. If the electrons do not have a Maxwellian distribution the actual distribution can be represented as the sum of several Maxwellians, each with a separate temperature." END_OBJECT = DSINSTPARMD ================================================================================ /*************** DATASET INSTRUMENT PARAMETER DESCRIPTION TEMPLATE ************/ /* Template: Data Set Instrument Parameter Description Template Rev: 19890121 */ /* Note: This template shall be completed for any */ /* data set or instrument parameter description. */ /* Hierarchy: DSINSTPARMD */ OBJECT = DSINSTPARMD DATA_SET_OR_INSTRUMENT_PARM_NM = "POSITION VECTOR" DATA_SET_OR_INST_PARM_DESC = "A position vector is a triad which describes the location of a point in 3-space relative to some origin." END_OBJECT = DSINSTPARMD