| DATA_SET_DESCRIPTION |
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.
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