Data Set Overview : The Cassini Radio Science Enceladus Gravity Science experiment (ENGR3) Raw Data Archive is a time-ordered collection of radio science raw data acquired on March 11 and March 13, 2008, during the Tour subphase of the Cassini mission. The DATA_SET_ID 'CO-SSA-RSS-1-ENGR3-V1.0' includes the following components: Instrument host (i.e., 'CO' for CASSINI ORBITER) Target (i.e., 'SSA' for Saturn Satellite) Instrument (i.e., 'RSS' for Radio Science Subsystem) Data processing level number (i.e., '1') Description (i.e., 'ENGR3') Version number (i.e., 'V1.0') Two types of measurements were obtained; these are known as closed-loop and open-loop recordings. The closed-loop system uses a phase-lock loop in the receiver to track the downlink signal, reporting both amplitude and frequency 10 times per second. In the open-loop system, the signal is simply converted to a baseband frequency range; the entire passband is sampled and recorded at 1000 samples per second. The data set includes three primary data types. Tracking and Navigation Service Data Files (TNFs) are the most primitive (and most voluminous) product of the closed-loop system. Orbit Data Files (ODFs) are compressed versions of TNFs, specifically targeted to spacecraft navigators and scientists interested in gravity fields. Radio Science Receiver (RSR) files are the primary data type from the open-loop system. Parameters : The TNF is the primary output from the Cassini closed-loop system. Each TNF in the data set is accompanied by a PDS minimal label. TNF data fields include: High- or low-rate Doppler Range Uplink frequencies (ramps) Differential Range vs Integrated Doppler (DRVID) Allan deviation Smoothed noise Other information in TNF data records includes sample date and time; spacecraft ID; ground station and its configuration; status flags and values reported by various ground systems; calibration values, noise estimates, and tolerances (station delay, transmitter power, etc.); and signal strength. The ODF is a compressed version of the TNF. It contains the most important information (range, Doppler and frequency ramps) needed by spacecraft navigators, and investigators interested in determining gravitational fields. Each ODF is accompanied by a full PDS label which describes both the content and format of the associated file. ODF data fields include: One-way Doppler (Hertz) Two-way Doppler (Hertz) Three-way Doppler (Hertz) SRA planetary operational discrete spectrum range (range units) The Radio Science Receiver (RSR) files are the primary output from the Cassini open-loop system and they contain 16-bit samples of receiver output. Each RSR file is accompanied by a full PDS label which describes both the content and format of the file at the bit level. Processing : The open-loop Radio Science Receiver (RSR) files are screened for gaps. No gaps were found in the RSR files for ENGR3. TNFs are screened for data/contents problems, which are corrected if/as possible before the files are released by the JPL multimission Radio Metric Data Conditioning Team (RMDCT). ODFs are constructed from subsets of TNF data by the RMDCT. The closed-loop Tracking and Navigation Service Files (TNFs) and the Orbit Data Files (ODFs) for the Cassini ENGR3 are constructed so that each file contains the data for each day. Primary Data : The primary data are stored on DVD volumes in subdirectories TNF, ODF, and RSR in per-day directories ENGR3_ddd (where ddd specifies the day of year based on the start time of the data). Users should refer to the INDEX/CUMINDEX.TAB listing to locate primary data files. TNFs are stored in the TNF directory on archival volumes. File names are of the form sssttaayyyy_ddd_hhmmxuuwVn.TNF, where 'sss' is the sequence/orbit id (e.g., S23), 'tt' is the target id (e.g., SA),'aa' is the activity/experiment id (e.g., GS), 'yyyy_ddd_hhmm' is the date and time for the start of included data (e.g., 2006_251_1151), 'xuu' is the transmitter band and uplink station (e.g., X14), 'w' is the ground mode or 'way' (e.g., M for multiple ground modes) and Vn is the file version number (e.g., V1). The PDS label has file name sssttaayyyy_ddd_hhmmxuuwVn.LBL. For this archive, the typical TNF contains about 200 Mbytes. ODFs are stored in the ODF directory on archival volumes. File names are of the form sssttaayyyy_ddd_hhmmxuuwVn.ODF. The PDS label has file name sssttaayyyy_ddd_hhmmxuuwVn.LBL. For this archive, the typical ODF contains about 7 Mbytes. RSR files are stored in the RSR directory on archival volumes. File names are of the form sssttaayyyyddd_hhmmxuudrrPD.rcs, where 'sss' is the sequence, (e.g., S23), 'tt' is the target, (e.g., SA), 'aa' is the activity, (e.g., GS), 'yyyy' is the year, (e.g., 2006), 'hhmm' is the start time, (e.g., 2330), 'xuu' is the uplink band and uplinking station, (e.g., X14), 'drr' is the downlink band and receiving station, (e.g., K25), P is the polarization, (e.g., R for right circular polarization), and 'rcs' is the RSR, channel and subchannel that were used to collect the data (e.g., 3A1). The PDS label has file name sssttaayyyyddd_hhmmxuudrrPD.LBL. The typical RSR contains from about 30 Mbytes to about 165 Mbytes depending on Doppler mode and station (i.e., track duration). Secondary Data : Secondary data are needed for proper analysis and interpretation of the radio data (file types TNF, ODF, and RSR). Secondary data that cover a time span of 24 hours or less are stored in subdirectories of ENGR3_ddd (i.e., 158, PD1, PD2 and TLM). Secondary data that cover a time span greater than 24 hours are provided in subdirectories CKF, EOP, ION, SPK and TRO in the ENGR3_ANCILLARY directory. Users should refer to the INDEX/CUMINDEX.TAB listing to locate secondary data files. 0158-Monitor Files (158 Directory) --------------------------------------------------- 0158-Monitor files are ASCII files with names sssttaayyyy_ddd_hhmm_hhmmrr.158 where 'hhmm_hhmm' is the start and end time of the file and 'rr' is the receiving station. They are channelized DSN Monitor Data files (new format) and they are produced at JPL by a Query Server operating on DSN Monitor packets stored in the JPL Telemetry Delivery System (TDS) Data Base. Each 0158-Monitor file is accompanied by a PDS label with file name sssttaayyyy_ddd_hhmm_hhmmrr.LBL. Typical file size is 10 MB. Path Delay Files (PD1 and PD2 Directories) ----------------------------------------------------------- Path Delay files are ASCII files and they are produced by the RSSG at JPL. File names have the form sssttaayyyy_ddd_hhmm_hhmmrr.PD1 (stored in the PD1 directory - the '1' in 'PD1' indicates that the data have been collected from Advanced Water Vapor Radiometer (AWVR) Unit 1) and sssttaayyyy_ddd_hhmm_hhmmrr.PD2 (stored in the PD2 directory - the '2' in 'PD2' indicates that the data have been collected from AWVR Unit 2) where 'hhmm_hhmm' is the start and end time of the data and rr is the receiving station. Each Path Delay file is accompanied by a PDS minimal label with file name sssttaayyyy_ddd_hhmm_hhmmrr.LBL. Typical file size is 135 KB. Telemetry Files (TLM Directory) --------------------------------------------------- Telemetry files are ASCII files with names sssttaayyyy_ddd_hhmm_hhmm.TLM where 'hhmm_hhmm' is the start and end time of the file. They are channelized DSN Telemetry Data files and they are produced at JPL by a Query Server operating on DSN Telemetry packets stored in the JPL Telemetry Delivery System (TDS) Data Base. Each Telemetry file is accompanied by a PDS label with file name sssttaayyyy_ddd_hhmm_hhmm.LBL. Typical file size is 50 MB. The available Telemetry channels, their names and definitions are: Telemetry Name Definition Channel # S-0181 KAT_UNLOCK Ka-Band Translator (KAT) Receiver Lock Latch S-0182 SBT_STATE_SW S-Band Transmitter (SBT) On/Off State (Commanded Mode) S-0183 KAT_STATE_SW KAT On/Off State (Commanded Mode) S-0185 KEX_STATE Ka-Band Exciter (KEX) On/Off State S-0186 KAT_STATE_HW KAT Off/On (Actual Status) S-0188 KTWT_SBY_HW Ka-Band Traveling Wave Tube Amplifier (KATWTA) Standby Enable/Inhibit (Actual Status) S-0189 KAT_RCVR_LCK KAT Receiver Locked/Unlocked S-0190 SBT_STATE_HW SBT Off/On (Actual Status) S-0191 SBT_REF_HW SBT Reference (Actual Status) S-0192 SBT_REF_SW SBT Reference (Commanded Mode) S-0193 KTWT_SBY_SW KATWTA Standby Enable/Inhibit (Commanded Mode) S-0166 KTWT_P_IN_r KATWTA Input Power Level (Residual) S-0164 KTWT_P_OUT_r KATWTA Output Power Level (Residual) S-0100 KAT_SPE_a KAT Receiver Static Phase Error (Telemetry Control Unit (TCU) A) S-0102 SBT_P_OUT_a SBT Output Power Level (TCU A) S-0104 KEX_P_OUT_a KEX Output Power Level (TCU A) S-0106 KEX_X_PWR_a KEX X-Band Power Level (TCU A) S-0108 KEX_PCV_a KEX Power Conv Voltage (TCU A) S-0112 KTWT_HLX_I_a KATWTA Helix Current (TCU A) S-0114 KTWT_P_OUT_a KATWTA Output Power Level (TCU A) S-0116 KTWT_P_IN_a KATWTA Input Power Level (TCU A) S-0118 KTWT_CTH_I_a KATWTA Cathode Current (TCU A) S-0120 KAT_TEMP_a KAT Temperature (TCU A) S-0122 SBT_TEMP_a SBT Temperature (TCU A) S-0124 KTWT_TEMP_a KATWTA Temperature (TCU A) S-0126 KEX_TEMP_a KEX Temperature (TCU A) S-0128 KTWT_CURR_a KATWTA Prime Current (TCU A) C-Kernel Files (CKF Directory) --------------------------------------------------- C-Kernel Files are in transfer format and they are produced by the Cassini Attitude and Articulation Control Subsystem team (AACS). File names have the form sssttaayyyy_ddd_yyyy_ddd.CKF where 'yyyy_ddd_yyyy_ddd is the start and end time of the file. Each C-Kernel file is accompanied by a PDS minimal label with file name sssttaayyyy_ddd_yyyy_ddd.LBL. Typical file size is 18 MB. Earth Orientation Parameter files (EOP Directory) --------------------------------------------------- Earth Orientation Parameter files are ASCII files and they are produced by the Kalman Earth Orientation Filter (KEOF) Group at JPL. File names have the form sssttaayyyy_ddd_yyyy_ddd.EOP. Each EOP file is accompanied by a PDS minimal label with file name sssttaayyyy_ddd_yyyy_ddd.LBL. Typical file size is 24 KB. Ionosphere Calibration Files (ION Directory) --------------------------------------------------- Ionosphere Calibration files are produced by the Tracking System Analytic Calibration (TSAC) Group at JPL. They provide historical and predicted Earth ionospheric conditions. File names have the form sssttaayyyy_ddd_yyyy_ddd.ION. Each ION file is accompanied by a PDS minimal label with file name sssttaayyyy_ddd_yyyy_ddd.LBL. Typical file size is 23 KB. Spacecraft/Planetary Ephemeris (SP-Kernel) Files (SPK Directory) ---------------------------------------------------------- Spacecraft/Planetary Ephemeris Files (also known as SP kernels or SPK files) are produced by the Cassini Navigation Team (NAV). These files give spacecraft and planetary ephemerides. File names have the form sssttaayyyy_ddd_yyyy_ddd.SPK. Each SPK file is accompanied by a PDS minimal label with file name having the form sssttaayyyy_ddd_yyyy_ddd.LBL. Troposphere Calibration Files (TRO Directory) --------------------------------------------------- Troposphere Calibration files are produced by the Tracking System Analytic Calibration (TSAC) Group at JPL. They provide historical and predicted Earth tropospheric conditions. File names have the form sssttaayyyy_ddd_yyyy_ddd.TRO. Each TRO file is accompanied by a PDS minimal label with file name sssttaayyyy_ddd_yyyy_ddd.LBL. Typical file size is 120 KB. Files in the CALIB Directory : The CALIB directory contains a Leapsecond kernel file, a Spacecraft Clock Conversion file, and a Boresight Calibration Report. All files in the CALIB directory are ASCII text files with variable length records delimited by ASCII carriage-return line-feed pairs. All file names in this directory contain the string 'yymmdd', where yy, mm, dd indicate the year, month and day of the file creation. Leapsecond kernel files are a record of leap seconds (past and predicted) that allow proper conversion between ephemeris time and UTC. File names are of the form: LSK_yymmdd.TLS Each file LSK_yymmdd.TLS is accompanied by a PDS detached minimal label with name LSK_yymmdd.LBL. Spacecraft Clock Conversion files allow time measured by the spacecraft clock to be converted to other time systems (e.g., ephemeris time or UTC). File names are of the form: TSC_yymmdd.SCK Each file TSC_yymmdd.SCK is accompanied by a PDS detached minimal label with name TSC_yymmdd.LBL. The Boresight Calibration Reports are produced by the Radio Science Systems Group (RSSG) at JPL. The naming convention for these files is: BORESIGHT_yymmdd.TXT Coordinate System : SPK files are produced in the J2000 inertial reference frame. Other data types are not dependent on any definition of a coordinate system. Software : Software for parsing, reducing, and analyzing data such as these has been developed at JPL and elsewhere. Because such software must usually operate at the bit-level and is written for a narrow range of platforms, it is unsuitable for general distribution. As such, no software is included with this archival data set. Media/Format : The archival data set is written on DVD-R media. The DVD-R volumes conform to the 'UDF_ISO-9660_BRIDGE' structure as required by PDS.

Overview : In general, this is a good data set. Review : This archival data set was reviewed by the Cassini Radio Science Team prior to submission to the Planetary Data System (PDS). Data Coverage and Quality : The data are contained in one volume (DVD), CORS_0240, and they cover the Radio Science Enceladus Gravity Science Enhancement experiments, (activity/experiment id: GS), conducted on August 10 and 12, 2008 and the Enceladus Gravity Field experiments, (activity/experiment id: GF), conducted on August 11 and 12, 2008. There are no known problems with this data set. Limitations : The limitations in this data set follow from the quality of the execution, which is described above under Data Coverage and Quality.