Data Set Overview : The Mars Reconnaissance Orbiter (MRO) Gravity Science (GR) Raw Data Archive (RDA) is the set of raw and partially processed radio science data collected during the MRO mission to Mars.  The earliest data in this data set were collected on 2006-08-30.  Two types of measurements were conducted, known as closed- and open-loop recordings. The closed-loop system used a phase-lock loop in the ground receiver to track the downlink signal, reporting both amplitude and frequency at rates typically of 1-10 times per second. In the open-loop system, the signal was simply converted to a baseband frequency range; the entire passband was sampled and recorded for later processing. Typical open-loop sampling rates for MRO were 1000 samples per second. Closed-loop data are efficient for characterizing slowly changing signals and are the input to operational navigation and orbit-determination processes. Open-loop data (because of their much higher rate and volume) are collected only when the signal is expected to be very dynamic -- such as during a spacecraft maneuver or an occultation.  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 records (RSRs) are the primary data type from the open-loop system.  Typical users of these data might analyze range and Doppler measurements in ODFs to reconstruct the spacecraft trajectory. Relevant questions would include the measurement uncertainties in range and Doppler at different DSN antennas; the uncertainties could set constraints on any model of Mars' gravity field developed later, for example.  The TNF data are generally reserved for use in more sophisticated investigations or where information beyond what is available in the ODF may be required. For example, the TNF may be used to extract the station uplink frequency ramps, which give the tuning of the uplink transmitted signal in cases when a constant frequency is inadequate.  RSR data were collected when the signal transmitted by the spacecraft was expected to be particularly dynamic, such as during a radio occultation by the atmosphere. When an occultation was observed using an RSR, the spacecraft was usually configured to be in a carrier-only mode (no telemetry modulation) and the ground equipment was operated by the Radio Science Systems Group at JPL. Two variations of the RSR were used during MRO; see the 'Data' section below for details.   Parameters : The TNF is the primary output from the MRO closed-loop system. In the TNF about 20 record types are defined, each designed for a particular audience, although it was frequently the case that users needed more than one record type. The emphasis of the data is on phase of the transmitted and received signals. Each TNF is accompanied by a PDS minimal label which points to a software specification document (TNF_SIS.TXT) in the DOCUMENT directory of the archive for detailed descriptions of the records and fields.  The ODF is a compressed version of the TNF. It contains the most important information (range, Doppler and frequency ramps) needed by spacecraft investigators, and investigators interested in determining gravity 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:  Narrowband spacecraft VLBI, Doppler mode (cycles) Narrowband spacecraft VLBI, phase mode (cycles) Narrowband quasar VLBI, Doppler mode (cycles) Narrowband quasar VLBI, phase mode (cycles) Wideband spacecraft VLBI (nanoseconds) Wideband quasar VLBI (nanoseconds) One-way Doppler (Hertz) Two-way Doppler (Hertz) Three-way Doppler (Hertz) One-way total count phase (cycles) Two-way total count phase (cycles) Three-way total count phase (cycles) PRA planetary operational discrete spectrum range (range units) SRA planetary operational discrete spectrum range (range units) RE(GSTDN) range (nanoseconds) Azimuth angle (degrees) Elevation angle (degrees) Hour angle (degrees) Declination angle (degrees)  Radio Science Receiver (RSR) records contain samples of open loop receiver output; the samples are complex and can have 1-16 bits in both the in-phase (I) and quadrature (Q) components, depending on sampling rate and precision requested. Sampling rates between 1 ksps and 16 Msps may be requested. Each RSR file is accompanied by a full PDS label which describes both the format and the content at the bit level. RSR data collected early in the MRO mission are described by original documentation [JPLD-16765]. Beginning on January 16, 2008, externally generated frequency predictions for tuning the RSR were provided in a companion downlink frequency (DLF) file, which must be used in conjunction with the RSR records [KAHAN2009].   Processing : Typical TNFs contained data from a 24-hour period, combining data from several antennas if there were multiple passes in one day. The files archived for MRO were not screened for 'bad' points.  ODFs are abstracted from subsets of TNF data. A full PDS label accompanies each ODF file and gives a bit level description of the content and format.  RSR data were modified during Ground Data System handling so that MISSION_ID in the Primary Header CHDO was set to 5. Data which were recorded on the VLBI Science Receiver (VSR), then converted to RSR format, were assigned the following values in the header(s): MINOR_DATA_CLASS : 5 (normally 4) Primary Header CHDO ORIGINATOR_ID : 123 (normally 48) Secondary Header CHDO LAST_MODIFIER_ID : 123 (normally 48) Secondary Header CHDO A VSR was used for MRO when all of the available RSRs had been assigned to other missions.   Data : The data set contains primary data and secondary data. Primary data are those files which would normally be used to derive science products and investigation results. Secondary data are needed for the processing or interpretation of primary data but are not usually considered to have science value of their own. There are three types of primary data. Listings of primary and secondary files can be found in INDEX/INDEX.TAB for the data set (as of the most recent delivery).  TNFs contain the most primitive (and most voluminous) output from the closed-loop radio science system; they are stored in the TNF directory. They have file names of the form MROMAGRyyyy_ddd_hhmmXuuwVn.TNF where 'MROMAGR' identifies the mission and the data set; 'yyyy' is the four-digit year, 'ddd' is the three-digit day-of-year, 'hh' is the two-digit hour, and 'mm' is the two-digit minute at the beginning of the file; 'X' indicates an X-Band uplink ('N' denotes no uplink); 'uu' indicates the uplink station (set to 'NN' for no uplink or 'MM' for two or more uplinking stations during the time interval covered), 'w' indicates the downlink mode ('1', '2', '3', or 'M' for 1-way, 2-way, 3-way, or 'multiple', respectively), and 'Vn' indicates the version number of the file. A detached PDS minimal label accompanies each TNF; label files have names of the form MROMAGRyyyy_ddd_hhmmXuuwVn.LBL. TNFs in this data set were usually generated at a 1-second sampling rate.  ODFs are stored in the ODF directory. ODFs are edited and/or compressed derivatives of TNFs. File names are of the form MROMAGRyyyy_ddd_hhmmXuuwVn.ODF where the field interpretations are the same as for the TNF. The ODF label has file name MROMAGRyyyy_ddd_hhmmXuuwVn.LBL. The typical ODF contains about 3 Mbytes. ODFs in this data set were usually generated at a 1-second sampling rate.  RSR files are stored in the RSR directory; they are the primary output of the open-loop radio science system. RSR files have names of the form 074MAOZyyyyddd_hhmmXuuYvvQS.abc where '074' is the spacecraft number; 'MAO' denotes Mars occultation; 'Z' is either 'E' for egress or 'I' for ingress; 'yyyy' is the four-digit year, 'ddd' is the day of year, 'hh' is the two-digit hour, and 'mm' is the two-digit minute when data began; 'X' is the uplink band (set to 'N' if there was no uplink); 'uu' is the uplink station (or 'NN' for none or 'MM' for multiple); 'Y' is the downlink band; 'vv' is the receiving station; 'Q' is the receiving polarization ('R' for right-circular or 'L' for left-circular); 'S' indicates the data source ('D' for standard data originating on the RSR [JPLD-16765], 'M' for non-standard RSR data [KAHAN2009], 'V' for VSR data converted to RSR format, and 'W' for wide-band VSR data converted to RSR format); and 'abc' identifies the RSR, the RSR channel, and the RSR sub-channel of the recording. Each RSR file is accompanied by a full PDS label which describes both the format and the content of the data file; the label file name has the form 074MAOZyyyyddd_hhmmXuuYvvQS.LBL.  NB: RSR data were collected using four versions of data acquisition software, identified by 'S' in the file name (see above). 'D' files are standard, have standard labels, and are documented in [JPLD-16765]. Although 'V' and 'W' files were collected using different systems, the data files have been converted to the [JPLD-16765] format. A few of the fields in the 'V' and 'W' headers may have values that would not be expected in the 'D' format. 'M' files are non-standard, have different labels, and require different processing, as documented in [KAHAN2009]. 'D' files were collected early in the MRO mission; after 2008-01-16, all MRO RSR files were 'M' files. Processing of the 'M' files requires use of Downlink Frequency (DLF) Files. The documents [JPLD-16765] and [KAHAN2009] can be found in the DOCUMENT directory of this archive.   Secondary Data : An extensive set of ancillary files is needed for proper analysis and interpretation of the data. In the paragraphs below 'yyyy_ddd_yyyy_ddd' gives the start and end dates of the data in the file. All ASCII files have records delimited by an ASCII carriage-return (ASCII 13) line-feed (ASCII 10) pair. In some cases (especially for NAIF files) the  may need to be converted to either  or  before the file is used on the local machine.  Antenna Gimbal and Solar Array Kernel Files (AGK and SAK Directories) ------------------------------------------- Antenna Gimbal Kernel files and Solar Array Kernel Files were produced by the JPL Navigation and Ancillary Information Facility (NAIF). Each AGK file contains information on the state of the HGA azimuth and elevation gimbals as a function of time. Each SAK file contains information on the solar array gimbals. These are ASCII files in NAIF transfer format. File names have the form MROMAGRyyyy_ddd_yyyy_ddd.AGK or MROMAGRyyyy_ddd_yyyy_ddd.SAK. Each AGK or SAK file is accompanied by a PDS minimal label with file name MROMAGRyyyy_ddd_yyyy_ddd.LBL. Typical file sizes are 1 MByte.  Downlink Frequency Files (DLF Directory) ---------------------------------------- Downlink Frequency files are ASCII files produced by the DSN for tuning an open-loop receiver (RSR) during some radio science activities. They list the best pre-experiment estimates of the spacecraft sky frequency at specific times and a set of Everett polynomial coefficients for interpolation. File names have the form MROMAGRyyyy_ddd_hhmmXvvwVn.DLF, where 'X indicates that X-Band is used for downlink, 'vv' is the downlink station number, 'w' is the downlink mode ('1' for one-way, '2' for two-way, '3' for three-way, or 'M' for multiple), and 'Vn' is the version number. Each file is accompanied by a PDS detached label having file name MROMAGRyyyy_ddd_hhmmXvvwVn.LBL. Typical file size is 250 KB.  Earth Orientation Parameter Files (EOP Directory) --------------------------------------------------- Earth Orientation Parameter files are ASCII files produced by the Kalman Earth Orientation Filter (KEOF) Group at JPL. File names have the form MROMAGRyyyy_ddd_yyyy_ddd.EOP. Each EOP file is accompanied by a PDS minimal label with file name MROMAGRyyyy_ddd_yyyy_ddd.LBL. Typical file size is 24 KB.  Ionosphere Calibration Files (ION Directory) --------------------------------------------------- Ionosphere Calibration files are ASCII files produced by the Tracking System Analytic Calibration (TSAC) Group at JPL. They provide historical and predicted Earth ionospheric conditions. File names have the form MROMAGRyyyy_ddd_yyyy_ddd.ION. Each ION file is accompanied by a PDS minimal label with file name MROMAGRyyyy_ddd_yyyy_ddd.LBL. Typical file size is 23 KB.  Light Time Files (LTF Directory) --------------------------------------------------- Light Time files were produced by the MRO Navigation Team (NAV). They give radio propagation time from the spacecraft to Earth vs time. These are ASCII files of fixed length records. File names have the form MROMAGRyyyy_ddd_yyyy_ddd.LTF. Each LTF file is accompanied by a PDS minimal label with file name MROMAGRyyyy_ddd_yyyy_ddd.LBL. Typical file sizes are less than 1 MB.  Maneuver Performance Data Files (MPD Directory) --------------------------------------------------- Maneuver Performance Data files were produced by the MRO Spacecraft Team (SCT). They contain estimates of spacecraft mass and center of mass; moments of inertia; thruster locations, directions, and magnitudes; and propellant flow rate. These are ASCII files of variable length records. File names have the form MROMAGRyyyy_ddd_yyyy_ddd.MPD. Each MPD file is accompanied by a PDS minimal label with file name sssttaayyyy_ddd_yyyy_ddd.LBL. Typical file sizes are 4 kB.  Small Forces File (SFF Directory) --------------------------------------------------- Small Forces Files were created from the MRO spacecraft engineering telemetry stream. These are ASCII files of variable length records. File names have the form MROMAGRyyyy_ddd_yyyy_ddd.MPD. Each SFF file is accompanied by a PDS minimal label with file name MROMAGRyyyy_ddd_yyyy_ddd.LBL. Typical file sizes are less than 0.1 MB. File content and structure is defined by SFF_MM_SIS_031217.htm in the DOCUMENT directory.  Spacecraft/Planetary/Satellite Ephemeris (SPK) Files (SPK Directory) --------------------------------------------------- Spacecraft/Planetary/Satellite Ephemeris Files (also known as SP kernels or SPK files) are produced by the MRO Navigation Team (NAV). One file includes spacecraft, planetary, and satellite ephemerides. File names have the form MROMAGRyyyy_ddd_yyyy_ddd.SPK. This SPK file is accompanied by a PDS minimal label with file name having the form MROMAGRyyyy_ddd_yyyy_ddd.LBL.  Spacecraft Attitude (CK) Files (ACK, CCK, SCK, ACP, CCP, and SCP Directories) --------------------------------------------------- C-Kernel Files are produced by the MRO Attitude and Articulation Control Subsystem team (AACS) and are in NAIF transfer format. File names have the form MROMAGRyyyy_ddd_yyyy_ddd.FFF where FFF is a three-character file name extension. The ACK, CCK, and SCK extensions denote the reconstructed high-gain antenna, spacecraft, and solar array C-Kernels, respectively. The ACP, CCP, and SCP extensions denote the predicted high-gain antenna, spacecraft, and solar array C-kernels, respectively. Each C-Kernel file is accompanied by a PDS minimal label with file name MROMAGRyyyy_ddd_yyyy_ddd.LBL. Typical file size is 18 MB.  Troposphere Calibration Files (TRO Directory) --------------------------------------------------- Troposphere Calibration files are ASCII files produced by the Tracking System Analytic Calibration (TSAC) Group at JPL. They provide historical and predicted Earth tropospheric conditions. File names have the form MROMAGRyyyy_ddd_yyyy_ddd.TRO. Each TRO file is accompanied by a PDS minimal label with file name MROMAGRyyyy_ddd_yyyy_ddd.LBL. Typical file size is 120 KB.  DSN Weather Files (WEA Directory) --------------------------------------------------- DSN Weather files were produced by the Tracking System Analytic Calibration (TSAC) Group at JPL. Files give weather calibration information for DSN complexes. These are ASCII files of variable length records. File names have the form MROMAGRyyyy_ddd_yyyy_ddd.WEA. WEA files were typically released weekly and contain all weather data for the complex since 1 January. Each WEA file is accompanied by a PDS minimal label with file name MROMAGRyyyy_ddd_yyyy_ddd.LBL. The files grow at the rate of approximately 90 kB per month.  Files in the CALIB Directory ---------------------------- Files in the CALIB directory are those likely to have wide applicability in working with the raw data. They help unpack and allow use of the raw data, rather than being 'instrument' calibration data per se. They include clock conversion files, tracking station locations and covariance files, a Structures kernel, and leapsecond files. Each file is accompanied by a PDS minimal label. In the paragraphs below 'yy' is the two-digit year, 'mm' is the two-digit month, and 'dd' is the two-digit day on which the file was created.  Spacecraft Clock Conversion files allow time measured by the spacecraft clock to be converted to other time systems (e.g., ephemeris time or UTC). These are ASCII files with names of the form: TSC_yymmdd.CLK. Each file TSC_yymmdd.CLK is accompanied by a PDS detached minimal label with name TSC_yymmdd.LBL.  The Topocentric Reference Definition kernel defines topocentric reference frames associated with each of the DSN stations. They were produced by the JPL/PDS Navigation Ancillary Information Facility (NAIF) for use with NAIF-developed and MRO-provided software. These are ASCII files with names of the form EARTH_TOPO_yymmdd.TF; each is accompanied by a detached label EARTH_TOPO_yymmdd.LBL.  The NAIF Structures kernel contains the relative locations of the MRO solar array and HGA structures. This is an ASCII file in NAIF transfer format. The file name has form MRO_yymmdd.STK. The file is accompanied by a detached minimal label with name MRO_yymmdd.LBL.  Leapsecond kernels contain a record of leap seconds (past and predicted) that allows proper conversion between ephemeris time and UTC. These are ASCII files with names of the form LSK_yymmdd.TLS. Each file LSK_yymmdd.TLS is accompanied by a PDS detached minimal label with name LSK_yymmdd.LBL.  Coordinate System : SPK and CK files can be converted to a wide range of coordinate frames by the NAIF reader routines.  Other data types are not dependent on definition of a coordinate system.   Software : Software for parsing, reducing, and analyzing data such as these has been developed at several institutions. Because such software must usually operate at the bit-level and is written for a narrow range of platforms, it is not suitable for general distribution. No software is included with this archival data set.   Media/Format : These data have been delivered to the PDS Geosciences Node electronically.

Overview : Data in this archival data set have been collected to support radio science investigations, including derivation of the gravity field of Mars. These are similar to data collected using other spacecraft and are believed to be generally of good quality.   Review : This data set was designed with oversight from the Planetary Data System. It was initially reviewed in May 2009 when the RSR and DLF data types were added.   Data Coverage and Quality : The ODFs in this archive contain data from all nominal MRO passes. They are primarily for the gravity investigation.  Initially, the MRO Radio Science investigation was limited to gravity science. S. Asmar saw an opportunity to acquire atmospheric occultation data and inquired with key members in the science community (in this specific field) who supported the idea. The MRO project then accepted a proposal to provide modest funding for this purpose.  All RSRs in this archive cover occultation activities when the spacecraft signal was carrier-only for Radio Science atmospheric investigations. Initial RSR files follow the format described by [JPLD-16765]. Open-loop (RSR) recordings for atmospheric science began March 4, 2007. Approximately one orbit per day was allocated to the Radio Science (Carrier Only) configuration for atmospheric occultations. As such, data cover a complete range of latitudes and longitudes on the Martian surface. The solar zenith angle, as of this writing, varies between 70 and 120 degrees. Ingress recordings were done with a two-way coherent signal from the spacecraft while egress recordings used the USO and were one-way. Beginning on January 16, 2008, RSRs conform to [KAHAN2009]. DLFs are provided starting January 16, 2008, so the user can reconstruct the receiver tuning. TNFs are provided for all RSRs so the user has the station uplink ramps, a necessary component in deriving the predicted sky frequency.   Limitations : The limitations in this data set follow from the quality of the execution, which is described above under Data Coverage and Quality.