Data Set Information
DATA_SET_NAME CASSINI V/E/J/S/SS RPWS SUMMARY KEY PARAMETER 60S V1.0
DATA_SET_ID CO-V/E/J/S/SS-RPWS-4-SUMM-KEY60S-V1.0
NSSDC_DATA_SET_ID
DATA_SET_TERSE_DESCRIPTION
DATA_SET_DESCRIPTION Data Set Overview ================= The Cassini Radio and Plasma Wave Science (RPWS) calibrated summary key parameter data set includes reduced temporal and spectral resolution spectral information calibrated in units of spectral density for the entire Cassini mission. This data set includes calibrated values binned and averaged within 1 minute by 0.1 decade spectral channels for all times during the mission including the two Venus flybys, the Earth flyby, the Jupiter flyby, interplanetary cruise, and the entire Saturn tour. Data for this data set are acquired by the RPWS Low Frequency Receiver (LFR), Medium Frequency Receiver (MFR), and High Frequency Receiver (HFR). Data are presented in a set of fixed-record-length tables. This data set is intended to provide numerical summary data which can be used in conjunction with other Cassini fields and particles key parameter data sets to establish trends, select events, or simply as a browse data set for the Cassini RPWS archive. This data set should be among the first used by a user of any of the RPWS archive as it will lead one to information required to search for more detailed or highly specialized products. Parameters ========== This data set comprises electric and magnetic field spectral densities for each sensor, binned and averaged (median) into moderate resolution frequency and time bins. We use 10 spectral channels per decade logarithmically spaced in frequency, usually from 1 Hz to 16 MHz, and a 1-minute time step. Processing ========== Data in this data set were processed by the use of a number of software programs which assemble segmented mini-packets in the raw telemetry packets into complete sets, de-compress the data that were compressed by one of a number of compression algorithms by the RPWS flight software onboard, apply conversion lookup tables or algorithms to convert telemetry data numbers into physical units, make any corrections required for antenna capacitive loading or other effects, bin the measurements into frequency and time bins, and then determine the median of all measurements within a bin. These data are calibrated using the best calibration tables and algorithms available at the time the data were archived. See chapters 5 - 11 of the RPWSCAL document in the DOCUMENT directory for details on how the data included in this data set were calibrated. Should a significant improvement in calibration become available, an erratum will be noted in the erratum section. Later versions of data products may contain better calibrations. It should be noted, however, that since measurements from different sensors are binned (via finding the median measurement in the bin) the resulting spectrum is an amalgamation of different sensors oriented in different directions. Hence, the detailed interpretation of this data set is not necessarily straight- forward. If the user is interested in the best calibrated value with a minimum of interpretational issues, the Low Rate Full resolution data product would be the best source of information. Data ==== The RPWS key parameter data set includes tables of wave spectra as a function of time using measurements from each of the various receivers of the RPWS, including the LFR, MFR, and HFR. Each table will contain fixed-length records including columns for time and spectral densities for each channel. Ancillary Data ============== Ancillary data included with this data set collection include a series of files that describe the modes of the RPWS as a function of time and provide a time-ordered listing of Instrument Expanded Block (IEB) trigger commands (the mode by which the RPWS is reconfigured). Also a detailed description of each of the modes (or IEBs) is provided. Other data which are ancillary to this data set but which are archived separately from this collection are the Navigation and Ancillary Information Facility's SPICE kernels describing the position and attitude of Cassini and various solar system bodies as a function of time. Coordinate System ================= The data in this data set are measurements of wave electric and magnetic fields measured by the RPWS electric and magnetic sensors. These fields are presented as detected by the sensors and are not rotated into any other coordinate system. If desired the SPICE kernels can be used with the SPICE toolkit to convert from the spacecraft frame to virtually any frame which may be of use in analyzing these data. However, for many purposes, the wave amplitudes are extremely useful and may be entirely adequate with no coordinate transformations at all. Software ======== Since the data are provided in text files as fully calibrated amplitudes, no example software is provided for reading these data. However, a platform-independent Java (TM) application is provided in EXTRAS/SOFTWARE/KEY_BROWSE.JAR which can read these data and produce spectrograms with user-selectable options. See README.TXT in the same directory for further information. Media/Format ============ These data are supplied to the Planetary Data System on DVD-R media using formats and standards of the PDS for such media.
DATA_SET_RELEASE_DATE 2018-07-01T00:00:00.000Z
START_TIME 1997-10-25T12:00:00.000Z
STOP_TIME 2017-09-15T12:00:00.000Z
MISSION_NAME CASSINI-HUYGENS
MISSION_START_DATE 1997-10-15T12:00:00.000Z
MISSION_STOP_DATE 2017-09-15T12:00:00.000Z
TARGET_NAME VENUS
EARTH
DIONE
HYPERION
TITAN
PHOEBE
SOLAR SYSTEM
RHEA
TETHYS
SATURN
ENCELADUS
MIMAS
IAPETUS
JUPITER
TARGET_TYPE PLANET
SATELLITE
PLANETARY SYSTEM
INSTRUMENT_HOST_ID CO
INSTRUMENT_NAME RADIO AND PLASMA WAVE SCIENCE
INSTRUMENT_ID RPWS
INSTRUMENT_TYPE PLASMA WAVE SPECTROMETER
NODE_NAME planetary plasma interactions
ARCHIVE_STATUS ARCHIVED - ACCUMULATING
CONFIDENCE_LEVEL_NOTE Confidence Level Overview ========================= This data set contains all low rate key parameter data for the Cassini RPWS instrument for the intervals described In the product label files. Every effort has been made to ensure that all data returned to JPL from the spacecraft are included and that the calibration is accurate. A column in each record indicates whether the confidence in the data in that record is high (0) or not (9). The middle band of the MFR (Band 2, 180 - 1500 Hz) has shown a tendency to have an increased noise level by as much as 10 dB at times, although there is no current explanation for this or known factor which would enable this condition to be predicted. In some instrument modes data are collected in the high band of the WFR which can be used to replace the data in MFR Band 2, although this replacement has not been done for this data set. The replacement data are included in the low resolution, fully calibrated data set, however. Review ====== The RPWS calibrated summary key parameter data will be reviewed internally by the Cassini RPWS team prior to release to the PDS. The data set will also be peer reviewed by the PDS. Data Coverage and Quality ========================= All data in the intervals described in the product label files are included, to the best of our knowledge and attempts to determine completeness. In general, the instrument was operated only briefly during early tour for the following intervals: 1. Antenna deployment 1997-10-25T00:00 - 1997-10-26T05:30 2. Venus 1 flyby 1998-04-26T12:54 - 1998-05-08T19:21* 3. Instrument Checkout 1998-12-30T09:10 - 1999-01-19T05:40 4. Venus 2 flyby 1999-06-24T09:08 - 1999-06-24T21:20 5. Earth flyby 1999-08-13T17:39 - 1999-09-14T22:20 *Actual interval for science data is much shorter than this. Beginning in February of 2000 the instrument was operated more-or-less continuously; two gaps of the order of six weeks were incurred for the purposes of loading new attitude control and command and data system flight software, gaps of a few days each were incurred approximately twice per year because of Huygens Probe testing, and gaps of several days in duration occurred during solar conjunction periods prior to 2002. Remaining gaps are due to spacecraft anomaly resolution or simply to downlink gaps, some of which were imposed by limitations on DSN station availability. Limitations =========== One measurement quality issue is occasional elevated noise levels (by a few to 10 dB) in the second band of the MFR. During tour, it is anticipated that data from the Waveform Receiver (WFR) sometimes referred to as the medium frequency digital receiver (MFDR) can be substituted for these in the full resolution data product (RPWS LOW RATE FULL). Beginning approximately with Saturn orbit insertion in early July 2005, the RPWS has shown increasing sensitivity in its electric field measurements below 2 kHz to interference from the spacecraft reaction wheels. The wheels are a source of electromagnetic interference in the magnetic channels at frequencies directly related to the rotation rate of the wheels due to a residual magnetic moment in the wheels. This level was predicted before launch and has been basically constant through flight. However, at the earliest opportunity to observe the interference of the wheels on the electric field measurements, there was essentially no detectable level of interference. However, after orbit insertion, it became clear with increasing time that the wheels were becoming an increasing source of interference in the electric field measurements at about 2 kHz and below. As of late 2005, the amplitude of this interference is of the order of 30 or 40 dB above the instrument noise level. The relation of the frequency of the electric interference to the rotation rate of the wheels is less direct than for the magnetic interference. There is a general correspondence, but not in detail. It appears that there are some frequencies more susceptible to the interference than others and when the wheel speed approaches these 'resonances', the interference becomes more visible. A working model for this interference proposes that radiation effects on some part(s) of the spacecraft, perhaps the thermal blankets, reduce the conductivity. Small vibrations of this part(s), then, with some residual differential charging then result in the electric field interference. This model is not confirmed and the true explanation of the interference is unknown, but the effects significantly complicate the interpretation of the electric field spectrum below 2 kHz. SCET Miscalculation =================== Version 1 of CORPWS data 2008-12-28 through 2011-06-30 were processed using invalid SPICE spacecraft clock kernels. Specifically the SCLKs which spice was asked to convert to SCETs were outside the valid correlation region. The error was subtle at first but continued to grow as SCLKs further from the correlated region were converted to SCETs. The net result was that incorrect SCET values were placed into the product files and product label files for these dates. The issue has been corrected and no longer affects any CORPWS datasets available from the PDS. The following table lists the maximum SCET errors by date.Start Date Stop Date Version Release Date Max SCET error----------- ---------- -------- ------------- ---------------2008-12-28 2009-01-12 1 2009-09-25 1.2 seconds2009-01-13 2009-01-29 1 2009-12-17 1.3 seconds2009-01-30 2009-02-12 1 2009-12-17 1.3 seconds2009-02-13 2009-03-01 1 2009-12-17 1.4 seconds2009-03-02 2009-03-29 1 2009-12-17 1.5 seconds2009-03-30 2009-04-19 1 2009-12-17 1.5 seconds2009-04-20 2009-05-16 1 2009-12-18 1.6 seconds2009-05-17 2009-06-12 1 2009-12-18 1.7 seconds2009-06-13 2009-06-26 1 2009-12-18 1.7 seconds2009-06-27 2009-07-09 1 2009-12-18 1.7 seconds2009-07-10 2009-07-25 1 2010-06-28 1.8 seconds2009-07-26 2009-08-17 1 2010-06-28 1.9 seconds2009-08-18 2009-09-09 1 2010-06-29 1.9 seconds2009-09-10 2009-10-01 1 2010-06-30 1.9 seconds2009-10-02 2009-10-21 1 2010-09-21 1.8 seconds2009-10-22 2009-11-14 1 2010-09-21 1.9 seconds2009-11-15 2009-12-10 1 2010-09-21 2.0 seconds2009-12-11 2009-12-23 1 2010-09-21 2.0 seconds2009-12-24 2010-01-13 1 2010-09-21 2.1 seconds2010-01-14 2010-01-23 1 2010-09-21 2.2 seconds2010-01-24 2010-02-02 1 2010-12-22 2.2 seconds2010-02-03 2010-02-17 1 2010-12-22 2.2 seconds2010-02-18 2010-02-27 1 2010-12-22 2.2 seconds2010-02-28 2010-03-11 1 2010-12-22 2.3 seconds2010-03-12 2010-03-22 1 2010-12-22 2.3 seconds2010-03-23 2010-03-31 1 2010-12-22 2.4 seconds2010-04-01 2010-04-16 1 2010-12-22 2.5 seconds2010-04-17 2010-04-29 1 2010-12-22 2.6 seconds2010-04-30 2010-05-10 1 2010-12-22 2.6 seconds2010-05-11 2010-05-25 1 2010-12-22 2.7 seconds2010-05-26 2010-06-08 1 2010-12-22 2.8 seconds2010-06-09 2010-06-25 1 2010-12-23 2.9 seconds2010-06-26 2010-08-07 1 2011-03-23 3.3 seconds2010-08-08 2010-09-08 1 2011-03-23 3.6 seconds2010-09-09 2010-10-15 1 2011-03-23 3.9 seconds2010-10-16 2010-11-29 1 2011-09-29 4.1 seconds2010-11-30 2011-01-03 1 2011-09-30 2.4 seconds2011-01-04 2011-02-13 1 2011-12-21 2.7 seconds2011-02-14 2011-03-24 1 2011-12-21 5.3 seconds2011-03-25 2011-04-24 1 2011-12-21 7.3 seconds2011-04-25 2011-05-09 1 2011-12-21 8.3 seconds2011-05-10 2011-05-26 1 2011-12-22 9.4 seconds2011-05-27 2011-06-12 1 2011-12-22 10.5 seconds2011-06-13 2011-06-30 1 2011-12-22 11.7 seconds Only data from 2008-12-28 through 2011-06-30 with VERSION_VERSION_ID = 1 are affected. If VERSION_VERSION_ID is greater than 1, or the date is before 2008-12-28, or the the date is after 2011-06-30, then the data in question is unaffected by this issue.
CITATION_DESCRIPTION Kurth, W.S., T.F. Averkamp, and L.J. Granroth, CASSINI V/E/J/S/SS RPWS SUMMARY KEY PARAMETER 60S V1.0, CO-V/E/J/S/SS-RPWS-4-SUMM-KEY60S-V1.0, NASA Planetary Data System, 2018.
ABSTRACT_TEXT The Cassini Radio and Plasma Wave Science (RPWS) calibrated summary key parameter data set includes reduced temporal and spectral resolution spectral information calibrated in units of spectral density for the entire Cassini mission. This data set includes calibrated values binned and averaged within 1 minute by 0.1 decade spectral channels for all times during the mission including the two Venus flybys, the Earth flyby, the Jupiter flyby, interplanetary cruise, and the entire Saturn tour. Data for this data set are acquired by the RPWS Low Frequency Receiver (LFR), Medium Frequency Receiver (MFR), and High Frequency Receiver (HFR). Data are presented in a set of fixed-record-length tables. This data set is intended to provide numerical summary data which can be used in conjunction with other Cassini fields and particles key parameter data sets to establish trends, select events, or simply as a browse data set for the Cassini RPWS archive. This data set should be among the first used by a user of any of the RPWS archive as it will lead one to information required to search for more detailed or highly specialized products.
PRODUCER_FULL_NAME DR. WILLIAM S. KURTH
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