Data Set Information
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| DATA_SET_NAME |
GALILEO PROBE DOPPLER WIND EXPERIMENT DATA V1.0
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| DATA_SET_ID |
GP-J-DWE-3-ENTRY-V1.0
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| NSSDC_DATA_SET_ID |
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| DATA_SET_TERSE_DESCRIPTION |
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| DATA_SET_DESCRIPTION |
Data Set Overview : A total of seven data sets are used to derive the wind profile. These include two trajectory data files (probe and orbiter), three frequency data files including the 'quicklook' data set comprising 1/2 resolution frequency data from the orbiter CDS, and two data files containing the full tape recorder (SDR) data. Additionally, the probe descent trajectory data are supplemented with probe descent velocity/altitude/pressure/time data from the Atmospheric Structure Instrument. Finally, the Jovian atmospheric structure, based on measurements by the Atmospheric Structure Instrument, is included in ASI4ATM.TAB. Reference Times --------------- time of entry (UT): 22:04:43.752 time of Minor Frame Zero (UT at the probe): 22:07:30.265 time of Minor Frame Zero (UT at the orbiter): 22:07:30.965 time of Lock (UT at the orbiter): 22:08:30.693 time of Loss of Lock (UT at the orbiter): 23:06:09 time between entry and Minor Frame Zero at the probe: 166.513 seconds time between entry and lock at the orbiter: 226.941 seconds time between Minor Frame Zero and lock at the orbiter: 59.728 seconds time between entry and loss of lock at the orbiter: 3,685.25 seconds total data (total time of lock): 57 minutes, 38.31 seconds : 3,458.31 seconds Total data points (frequencies): 5,015 out of a possible 5,174 total missing frequencies: 5,174 - 5,015 : 159 Note 1: Minor Frame Zero is the start time of the first minor frame of data in probe descent mode. This is the probe mission reference time. It differs between the probe and orbiter due to the propagation time between the probe and orbiter of about 0.7 seconds. The use of one time or the other (relative to the probe or the orbiter) depends on whether the instantaneous times of each frequency measurement and the trajectory parameters are referenced to times at the probe or the orbiter. Since the probe/orbiter trajectories, as well as the winds, are referenced to times at the probe, Minor Frame Zero at the probe is used rather than at the orbiter. Note 2: Lock is the time (UT) at which the orbiter locks onto the probe signal and starts recording probe science data. Data : Data files: CRS (Orbiter trajectory, ASCII): orbtrtrj.tab PSTF (Probe trajectory, ASCII): probetrj.tab CDS (Tape Recorder, half resolution frequency, ASCII): rsf0117a.adj SDR (Probe frequency data, ASCII): sdr0530a.tab SDR (Probe frequency data, ASCII): radio.tab ASI (Probe trajectory data from ASI, ASCII): asi2ref.tab Atmospheric Structure Data (ASCII): asi4atm.tab Frequency data: The frequency data sets come in two different forms. The 'Quick-Look' data are half-resolution and comprise probe radio link frequencies stored in the orbiter CDS every 4/3 seconds. These data files, designated as rsf (radio science frequencies) are described in more detail below. The System Data Record (SDR) data are from the tape recorder with a sampling frequency of 1.5 Hz (one sample every 2/3 seconds). The SDR data are described below. The probe and orbiter data files (PSTF and CRS, respectively) provide the probe and orbiter trajectories in time from entry. The PSTF file lists the probe position and velocity as a function of time from probe entry (defined to be the time of probe altitude equal to 450 km above the one bar reference surface). The probe descent trajectory is given in x,y,z,xdot,ydot,zdot in EME50 coordinates (defined below). The orbiter trajectory is also listed as x,y,z,xdot,ydot,zdot in EME50 coordinates as a function of time past 1950 in ephemeris time. CRS - Orbiter Trajectory Data File, ASCII ----------------------------------------- The orbiter trajectory, provided by the Galileo Navigation team at the Jet Propulsion Laboratory, is contained in a data file called a CRS file. The CRS data set provides the EME50 coordinates (x,y,z;xdot,ydot,zdot) of the center of Jupiter in an orbiter-centered system. The CRS file also provides auxiliary data such as GM, and the equatorial and polar radii for Jupiter. The times for the orbiter trajectory are given in year, day, hour, minute, second, and millisecond past 1950 in ephemeris time. The orbiter trajectory is converted from the spacecraft-centered EME50 coordinates to a Jupiter-centered JPPM (Jupiter Pole and Prime Meridian) frame. To make this conversion, the unit vectors in the direction of Jupiter's rotation axis (x_pole,y_pole,z_pole) and prime meridian (x_pm,y_pm,z_pm) in EME50 coordinates must be known. These are provided in the probe trajectory file PSTF. PSTF - Probe Trajectory Data File, ASCII ---------------------------------------- The Probe System Trajectory File (PSTF) provides the nominal descent profile of the probe from entry to the end of the descent mission. The PSTF file is generated by the ATMINT program, a key element of JPL's RLINK program set. The PSTF file is an ASCII file that contains 1) a header containing run identification information; 2) a listing of major program parameter values, including a table of probe aerodynamic coefficients, and 3) a descent trajectory profile which lists the probe's inertial and atmosphere relative motion in Jupiter's atmosphere as a function of time after entry. At the time of parachute deployment the profile is interrupted by a second aerodynamic characteristics table. This is followed by a listing of the probe positional and velocity vectors, the unit vectors in the vertical, west, and north directions at the probe, and the probe altitude relative to the one bar level, all as a function of time (seconds after entry). The probe position and velocity components are given in Jupiter-centered EME50 coordinates. Auxiliary data supplied in the PSTF file include 1) the probe entry time both in year, day of year, hour, minutes, and seconds in ephemeris time, and the number of seconds past 1950 again in ephemeris time; 2) the unit vectors in the direction of Jupiter's pole (z-axis), and the intersection between the prime meridian and Jupiter's equator (y-axis) in EME50 coordinates; 3) the atmosphere model (nominal Orton III); 4) Gravitational parameters (GM, J_2, J_4); 5) the polar and equatorial radii; 6) the planetary flattening; and 7) the system III rotation period of Jupiter. An x-axis is generated by standard techniques to complete the right-handed coordinate system. It should be noted that, although the probe entry time is provided in the PSTF file, for purposes of the wind retrieval the entry time is input separately, and can therefore be altered without the need for regenerating an entirely new PSTF data set. The PSTF file used (PSTF-OD126\_1s) provides the probe descent trajectory in 1 second increments and includes the effect of the late parachute deployment. Once the probe trajectory is converted from the Jupiter-centered EME50 coordinates to the JPPM reference frame, the probe positions and velocities are generated as a function of time after entry in a radius, latitude, longitude coordinate system. CDS (RSF) Frequency Data, ASCII ------------------------------- Due to the failure of the high gain antenna to deploy and concerns about the possible failure of the orbiter tape recorder, the probe data were stored in the memory of the orbiter Command and Data Subsystem as a backup. The CDS data stored in the CDS were at half resolution (every other time point) and therefore provided a frequency measurement every 4/3 seconds. The CDS data are an ASCII file of NCO frequency vs. time from lock and were used for the early wind analysis. The CDS (half-resolution) data are contained within the data file rsf0117a.adj. The 'adj' indicates that the data set is adjusted by removal of spurious frequency measurements and missing data. The first several lines of rsf0117a.adj are given below: 0.000 95:341:22: 8:30.693 1 30 96 C8 432029.71 1.333 95:341:22: 8:32. 26 1 30 96 75 432018.45 2.667 95:341:22: 8:33.360 1 30 96 1B 432006.24 4.000 95:341:22: 8:34.693 1 30 95 BE 431993.62 5.333 95:341:22: 8:36. 26 1 30 95 68 431981.95 Column one gives the time after lock (seconds) and the last column gives the NCO frequency in Hz. SDR Frequency Data (Tape Recorder) ---------------------------------- There are two SDR data sets presented in this archive. The first, designated sdr0530a.tab, is the probe frequency raw data as an ASCII data file. This file has several data outages of varying lengths, and several individual missing frequency measurements. Many of these missing measurements were filled in using the CDS data set. Including housekeeping and radioscience, the probe data were stored on the orbiter tape recorder for later playback to the ground. The probe signal frequency, measured every 2/3 seconds, as well as the other probe science and engineering data measured throughout the probe mission, was delivered in the form of binary System Data Records. The data file sdr0530a.tab is an ASCII file that was converted from binary for further analysis. Although the probe signal frequencies were measured every 2/3 seconds, some gaps existed in the data due to corrupted data, DSN outages, and possibly several bad spots on the tape recorder tape. Many of these gaps were filled by the CDS data. Out of 5,174 possible frequency measurements there are only 159 missing points, none consecutive. The SDR (tape-recorder) data are contained within data file radio.tab and include (where necessary) half-resolution data from the CDS file rsf0117a.adj to fill gaps in the data, and corrections for the timing errors. radio.tab is an ASCII file that lists NCO frequency vs. time from lock (seconds). The first several lines of radio.tab are given below. The columns are time from lock (seconds) and NCO frequency (Hz): .000 432029.712 .667 432024.013 1.334 432018.451 2.000 432012.481 Ancillary Data : Data from the probe Atmospheric Structure Instrument are used to supplement the Doppler wind analysis. Of primary importance are the probe descent velocity, and radius/altitude (above/below the one bar reference surface at the given latitude) vs. pressure/time. These data are included in the file asi2ref.tab. The first several lines of asi2ref.tab are provided below. The columns are column 1: time from minor frame zero (seconds) column 2: unused column 3: probe altitude (km above 1 bar) column 4: probe radial velocity (m/s) column 5: unused column 6: unused column 7: unused column 8: Probe latitude (planet-centered) column 9: Probe longitude at initial time point only column 10: unused column 11: unused column 12: unused 30.1600 0.0 16.000 98.747 0.0 0.0 0.0 6.41 359.468 0.0 0.0 0.0 50.4700 0.0 14.031 95.168 0.0 0.0 0.0 6.41 0.0 0.0 0.0 0.0 71.1400 0.0 12.098 91.866 0.0 0.0 0.0 6.41 0.0 0.0 0.0 0.0 91.2600 0.0 10.281 88.709 0.0 0.0 0.0 6.41 0.0 0.0 0.0 0.0 112.200 0.0 8.4539 85.822 0.0 0.0 0.0 6.41 0.0 0.0 0.0 0.0 134.400 0.0 6.5777 83.206 0.0 0.0 0.0 6.41 0.0 0.0 0.0 0.0 157.460 0.0 4.6867 80.797 0.0 0.0 0.0 6.41 0.0 0.0 0.0 0.0 The initial time point is 30.60 seconds after Minor Frame Zero, and the final time point is 3,422.44 seconds after Minor Frame Zero. Note: The total data used in the Doppler Wind Analysis is limited by the duration of the ASI data. Therefore, although the total time of lock is 3,458.31 seconds, only 3,361.33 seconds of data are used for the wind retrieval due to the lack of ASI data beyond 3,422.44 seconds after Minor Frame Zero. Other Data Sets Provided : FRED.TAB This ASCII file contains the frequency residuals for the Galileo Probe Doppler Wind Experiment prior to the wind measurements. The columns are Time from Entry in seconds Pressure at probe location (bar) Frequency Residuals before the wind retrieval (Hz) This file contains 5043 rows. The initial time point is 1995-12-07 22:08:31 (UT), corresponding to the initial Time from Entry of 227.3333 seconds. The final time point is 23:04:32 (UT), corresponding to Time from Entry of 3,588.6667 seconds. Note: the total time in this file (5043 time points) is 3,588.6667 - 227.3333 seconds : 3,361.33 seconds. This is less than the total time of lock provided above (3,458.31 seconds) and is due to the fact that data from the Atmospheric Structure Instrument was used to generate the probe descent profile (asi2ref.tab). Therefore, the total data are limited not by the time of loss of lock, but by the time at which the data provided by the ASI instrument team ended. The first several rows are shown below: 227.3333 0.5648 0.0000 228.0000 0.5664 0.3178 228.6667 0.5680 0.4498 229.3333 0.5696 0.2558 RESID.TAB This ASCII file contains data for the Galileo Probe Doppler Wind Experiment, including time from entry, time from link lock, altitude, pressure, and frequency residuals after the wind retrieval. The columns are Time from entry (seconds) Time from link lock (seconds) Altitude above 1 bar (km) Pressure at probe location (bar) Frequency Residuals after the wind retrieval (Hz) This file contains 5043 rows. The initial time point is 1995-12-07 22:08:31 (UT), corresponding to the initial Time from Entry of 227.3333 seconds. The final time point is 23:04:32 (UT), corresponding to Time from Entry of 3,588.6667 seconds. Note: the total time in this file (5043 time points) is 3,588.6667 - 227.3333 seconds : 3,361.33 seconds. This is less than the total time of lock provided above (3,458.31 seconds) and is due to the fact that data from the Atmospheric Structure Instrument was used to generate the probe descent profile (asi2ref.tab). Therefore, the total data are limited not by the time of loss of lock, but by the time at which the data provided by the ASI instrument team ended. The first several rows are shown below: 227.3330 0.392330 13.3990 0.5648 0.00000 228.0000 1.05900 13.3380 0.5664 0.37720 228.6670 1.72567 13.2770 0.5680 0.56510 229.3330 2.39233 13.2160 0.5696 0.42640 WIND.TAB This ASCII file contains wind data from the Galileo Probe Doppler Wind Experiment, including time from entry, time from lock, temperature, pressure and wind. The columns are Time from entry (seconds) Time from link lock (seconds) Temperature (K) Pressure at probe location (bar) Wind (m/s) This file contains 5043 rows. The initial time point is 1995-12-07 22:08:31 (UT), corresponding to the initial Time from Entry of 227.3333 seconds. The final time point is 23:04:32 (UT), corresponding to Time from Entry of 3,588.6667 seconds. Note: the total time in this file (5043 time points) is 3,588.6667 - 227.3333 seconds : 3,361.33 seconds. This is less than the total time of lock provided above (3,458.31 seconds) and is due to the fact that data from the Atmospheric Structure Instrument was used to generate the probe descent profile (asi2ref.tab). Therefore, the total data are limited not by the time of loss of lock, but by the time at which the data provided by the ASI instrument team ended. The first several rows are shown below: 227.3330 0.39200 138.1107 0.5648 86.54214 228.0000 1.05900 138.2380 0.5664 86.52588 228.6670 1.72600 138.3654 0.5680 86.51108 229.3330 2.39200 138.4927 0.5696 86.49774 Coordinate System : EME50 - Earth Mean Equator and Equinox of 1950 Coordinates ---------------------------------------------------------- The EME50 coordinate system is an inertial (non-rotating) cartesian coordinate frame. It is defined by the Earth's mean equator, Earth's vernal equinox, and Earth's rotation axis. The positive x-axis is directed towards the Earth's mean vernal equinox of date; the z-axis is aligned with Earth's mean rotation axis, and the y-axis is made to complete the right-handed coordinate frame. The epoch is 1950 (December 21, 1949 at 22:09:07 UT). Planetographic/Planetocentric Latitudes --------------------------------------- Planetographic/planetocentric latitudes are measured north (positive) and south (negative) of the equator. The planetographic latitude of a point on the reference surface is the angle between the equatorial plane and the normal to the surface at that point. The planetocentric latitude of a point is the angle between the line connecting the point to the center of mass and the equator [DAVIESETAL1983]. System III Longitudes --------------------- The Jupiter System III longitudes are defined by the rotation of Jovian decimetric and decametric radio noise, presumably co-rotating with Jupiter's magnetic field and core. [RIDDLE&WARWICK1976]. JPPM - Jupiter Pole and Prime Meridian Coordinates -------------------------------------------------- The Jupiter Pole/Prime Meridian system is an inertial cartesian coordinate system centered on Jupiter's center. The z-axis is along Jupiter's rotation axis, the y-axis is defined by the unit vector through the intersection of the system III (1965) Prime Meridian and the Jovian equator in EME50 at the epoch of probe entry, and the x-axis completes the right-handed coordinate system.
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| DATA_SET_RELEASE_DATE |
1996-12-08T00:00:00.000Z
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| START_TIME |
1995-12-07T09:05:44.000Z
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| STOP_TIME |
1995-12-07T11:35:44.000Z
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| MISSION_NAME |
GALILEO
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| MISSION_START_DATE |
1977-10-01T12:00:00.000Z
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| MISSION_STOP_DATE |
2003-09-21T12:00:00.000Z
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| TARGET_NAME |
JUPITER
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| TARGET_TYPE |
PLANET
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| INSTRUMENT_HOST_ID |
GP
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| INSTRUMENT_NAME |
DOPPLER WIND EXPERIMENT
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| INSTRUMENT_ID |
DWE
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| INSTRUMENT_TYPE |
RADIO SCIENCE
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| NODE_NAME |
Planetary Atmospheres
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| ARCHIVE_STATUS |
ARCHIVED
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| CONFIDENCE_LEVEL_NOTE |
Confidence Level Overview : Data Coverage and Quality ------------------------- There are several locations where frequency data points are missing. Several gaps existed due to tape recorder (SDR) problems, corrupted data, and DSN outages. Most of these gaps were filled with CDS data. Out of the maximum possible number of frequency measurements of 5,174 covering the period of lock (3,458.31 seconds), 5,015 were obtained. None of the missing points are consecutive so the largest gap is 4/3 second. At approximately 10 locations in the frequency profile, a null frequency measurement is observed. This is due to a timing mismatch between the RRH and the orbiter. Occasionally the orbiter will look for a frequency in an RRH buffer before the frequency has been placed in the buffer. The null measurements, resulting from a sampling period that is slightly longer than 2/3 seconds, occur approximately every 340 seconds. A portion of the SDR frequency data with the null measurement is shown below: REC1.DAT RRH DATA --11/20/92-- PLL MODE ONLY HHMMSS.SSS SFM SFI SFL FREQC FREQ(Hz) FTIME (SEC) RS FREQ (Hz)295 155339 798 048 098 242 3171058. 430229.321 196.667 430229.3209296 160019 767 048 098 199 3171015. 430223.487 197.334 430223.4870297 160659 731 048 098 157 3170973. 430217.789 198.000 430217.7887298 161339 701 048 098 113 3170929. 430211.819 198.667 430211.8190299 162019 670 048 098 068 3170884. 430205.714 199.334 430205.7137300 162659 634 048 098 017 3170833. 430198.794 200.000 430198.7944301 163339 599 000 000 000 0. .000 200.667 .0000301 164019 567 048 097 221 3170781. 430191.739 201.334 430191.7393302 164659 530 048 097 176 3170736. 430185.634 202.000 430185.6340303 165339 495 048 097 127 3170687. 430178.986 202.667 430178.9860 A simple method of treating this discontinuity is to remove the null frequency and recalculate the times. For example, the first point above is 196.667 seconds, the last is at 202.667 seconds. In this interval there are 9 valid frequency measurements. While the frequencies are unchanged, the corresponding times for each of the nine frequencies (for this example) are 196.667 + (n-1)*delta t where n:1,2,3,...9 and delta t is (202.667-196.667)/(n-1) : 0.75 seconds. This results in the listed frequencies (not including the null measurement) at times 196.667, 197.417, 198.167, 198.917, 199.667, 200.417, 201.167, 201.917, 202.667. The choice of 9 points is arbitrary. This averaging of n measurements over n+1 time points results in a shift in the apparent time of each frequency measurement of a fraction of a second.
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| CITATION_DESCRIPTION |
Citation TBD
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| ABSTRACT_TEXT |
A total of seven data sets are used to derive the wind profile. These include two trajectory data files (probe and orbiter), three frequency data files including the 'quicklook' data set comprising 1/2 resolution frequency data from the orbiter CDS, and two data files containing the full tape recorder (SDR) data. Additionally, the probe descent trajectory data are supplemented with probe descent velocity/altitude/pressure/time data from the Atmospheric Structure Instrument. Finally, the Jovian atmospheric structure, based on measurements by the Atmospheric Structure Instrument, is included.
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| PRODUCER_FULL_NAME |
DAVID ATKINSON
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| SEARCH/ACCESS DATA |
Atmospheres Online Archives
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