| DATA_SET_DESCRIPTION |
Data Set Overview
=================
The Mars Global Surveyor (MGS) Radio Science (RS) Raw Data
Archive (RDA) is a time-ordered collection of raw and partially
processed data collected during the MGS Mission to Mars.
For more information on the investigations see
[TYLERETAL1992] and [TYLERETAL2001].
This data set was collected during the Mars Orbit Insertion
(MOI) Phase -- while the spacecraft was on final approach to
Mars, entering Mars orbit, and adjusting the orbit in
preparation for the Mapping Phase. Most of the radio data
supported MGS Navigation activities. Occultations captured
during January-April 1998, November-December 1998, and
February-March 1999 and low periapsis passes over the poles
have intrinsic science value of their own.
Two types of measurements were conducted during MOI; these
are known as closed-loop and open-loop recordings. The closed-
loop system used a phase-lock loop in the 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 MGS were
5000 samples per second. Closed-loop data are efficient for
characterizing slowly changing signals; open-loop data
(because of their much higher volume) are collected only
when the signal is very dynamic -- such as during an
occultation.
The data set includes three primary data types. Archival
Tracking Data Files (ATDFs or TDFs) are the most primitive (and
most voluminous) product of the closed-loop system. Orbit Data
Files (ODFs) are edited versions of ATDFs, specifically
targeted to spacecraft navigators and scientists interested in
gravity fields. Original Data Records (ODRs) are the primary
data type from the open-loop system.
Typical users of these data might analyze range and Doppler
measurements in ATDFs or ODFs to derive the spacecraft
trajectory during MOI. Relevant questions would include the
measurement uncertainties in range and Doppler at different DSN
antennas; these could set constraints on any model of Mars'
gravity field developed later, for example. During MOI the
spacecraft orbit was lower than at any other time during the
mission; gravity investigators interested in detecting and
measuring concentrations of mass at or near the surface could
find the ODF's in this data set to be particularly interesting.
Users of ODRs could identify and characterize anomalous signals
within the recorded passband, derive the drift of the
UltraStable Oscillator (USO), and calculate Allan Deviation for
various radio science configurations. Data collected during
aerobraking could be used to infer the structure of the upper
Mars atmosphere.
Parameters
==========
The ATDF is the primary output from the MGS closed-loop system.
ATDFs have 150 fields, though not all had been assigned during
the MGS era. Each ATDF in the data set is accompanied by a
full PDS label which defines both the content and the format
(at the bit level) of the file. ATDF data fields include:
Range
High- or low-rate Doppler
High or low-rate downlink phase
Differential Range vs Integrated Doppler (DRVID)
Allan deviation
Smoothed noise
Uplink phase
Other information included in ATDF data records is 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 an edited version of the ATDF; it is a smaller file,
issued more frequently than the ATDF. It contains the most
important information (range and Doppler) needed by spacecraft
navigators and investigators interested in determining
gravitational fields of bodies such as Mars. 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)
Open loop data records (ODRs) contain 8- or 12-bit samples of
receiver output. Each block of (typically) 1000 data samples
is accompanied by a 166 byte header. Each ODR is accompanied
by a full PDS label which describes both the content and format
of the file at the bit level. Header information includes:
Date and time of the first data sample
Sample rate and channel assignments
Receiver local oscillator (POCA) frequency
Attenuator settings
RMS voltages at several stages in the receiving chain
Processing
==========
ATDFs are screened for 'bad' data points, which are removed
before the file is released by the Jet Propulsion Laboratory
(JPL) Radio Metric Data Conditioning Team (RMDCT).
ODFs are abstracted from subsets of ATDF data.
The open-loop data delivered to Stanford were usually in the
ODS (Original Data Stream) format. ODS packets were converted
to the older ODR (Original Data Record) format for consistency
in subsequent processing and archive. Headers applied by the
Ground Data System (GDS) during packet handling have not been
retained; they contained no additional information about the
data acquisition. In some cases, where the GDS corrupted the
ODS during delivery (or lost it entirely), data have been
recovered from tape in ODR format. The resultant data (whether
from ODS conversion or tape) accurately represent the output
of the DSCC Spectrum Processing (DSP) Subsystem at the DSN
station. A full PDS label accompanies each ODR file and gives
a bit level description of the content and format.
A 32-byte label at the beginning of each ODR tape is not
included in the data file. The 32-byte label gives the version
of the data taking software; this information has been copied
to the PDS label that accompanies the data file. The software
version recorded in the 'NOTE' keyword is more likely to be
accurate than the version recorded with the 'SOFTWARE_VERSION'
keyword. Because the 32-byte label is no longer part of the
data stream, users can treat the remaining file as an integral
number of fixed-length records. The 32-byte label was never
defined in the ODS.
Data
====
Data are stored on CD-WO volumes approximately chronologically.
CD volumes were usually defined by the dates of included
spacecraft engineering and DSN monitor data (data types ECH and
MCH, respectively). ECH and MCH files were the most regular,
and often the largest, collected on a daily basis. Files of
other types were sometimes delayed in delivery to Stanford and
may be out of strict chronological order on the CDs. Users
should consult listings in the INDEX/CUMINDEX.TAB file to
ascertain full coverage of each data type.
ATDFs were delivered approximately weekly during MGS MOI.
ATDFs are stored in the TDF directory on archival volumes.
File names are of the form ydddeeeC.TDF where y is the
one-digit year of the first data, ddd is the three-digit
day-of-year of the first data, eee is the three-digit day-
of-year of the last data, and C is a single letter (beginning
with 'A') denoting the sequence in which files with the same
ydddeee were handled. Generally ydddeeeB.TDF is a revised
version of ydddeeeA.TDF. The PDS label has file name
ydddeeeC.LBL. The typical ATDF contains about 39 Mbytes.
ODFs were issued at least daily throughout MGS MOI; during
periods of high spacecraft activity (such as around maneuvers)
ODFs were released as often as hourly. Most ODFs released
during MOI are included in the archival data set. Of those
that were missed, most were generated by special request, and
Stanford did not receive a release notice. ODFs are stored in
the ODF directory. File names are of the form ydddeeeC.ODF
where the file name components are the same as for the ATDF
(previous paragraph). In most cases ydddeeeB.ODF was NOT
simply a revised version of ydddeeeA.ODF; there were many
requests for special ODF processing -- to obtain higher time
resolution over short intervals, for example. The PDS label
has file name ydddeeeC.LBL. Typical ODF file sizes are small
multiples of 8064 bytes (e.g., less than 100 kB).
Original Data Records (ODRs) were produced whenever the DSP
was set to 'run' mode. These files are stored in the ODR
directory. In most cases, the entire DSP run was collected
into a single ODR file. But in other cases, it was more
convenient to subdivide the DSP data; queries were issued for
shorter time spans, and separate files were produced. File
names are of the form ydddhhmm.ODR where y is the one-digit
year of the first data, ddd is the day-of-year of the first
data, hh is the hour on which the first sample was taken, and
mm was the minute on which the first sample was taken. In
cases where two files had the same ydddhhmm (for example, two
DSN stations began recording at the same time, or a second query
was submitted for data which appeared suspicious after the
first query was processed), the less significant digit in mm
of the second file was converted to a letter ('0' became 'A',
'1' became 'B', ..., '9' became 'J'). In cases were three files
had the same ydddhhmm, the less significant mm digit was
converted to 'K', 'M', etc. The PDS label has file name
ydddhhmm.LBL.
At 5000 samples per second, a two-hour 12-bit test would yield
a 60 MB ODR -- one X-band (RCP) channel; 5 records per second,
each with 1000 12-bit samples and a 166-byte header. At
200 samples per second, an eight-hour 8-bit run would yield
a 33 MB ODR -- four channels (one X-RCP, the others null); 2
records per second with 100 8-bit samples per channel and a
166-byte header.
Ancillary Data
==============
An extensive set of ancillary files is needed for proper
analysis and interpretation of the radio data (file types
TDF, ODF, and ODR). These are organized in parallel
directories and stored approximately chronologically. When
a file type is not represented on a CD-WO volume, the
corresponding directory has been omitted. With the exception
of files stored in the CALIB directory, ancillary files
appear on only one CD-WO volume. Users should refer to
the INDEX/CUMINDEX.TAB listing to locate ancillary files.
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
decommutation maps, clock conversion files, files of
planetary constants, leapsecond files, and files needed for
display of data on the MGS Science Operations Planning
Computer (SOPC). Each file is accompanied by a PDS minimal
label.
Clock Conversion files were produced by the JPL/PDS
Navigation Ancillary Information Facility (NAIF) for use
with NAIF-developed and MGS-provided software. These are
ASCII files of variable length records. Each record is
delimited by an ASCII carriage-return (ASCII 13)
line-feed pair (ASCII 10), which may need to be
converted to either or before the file is used
on the local machine. File names have the form ydddeeeC.SCK
where y is the one-digit year of the first date covered,
ddd is the day-of-year of the first date covered, eee
is the day-of-year of the last date covered, and C is a
character denoting sequence when more than one file
with the same ydddeee is handled. C starts from 'A'
and progresses to 'B', 'C', etc. with increasing numbers
of similar coverage files. An alternate naming scheme was
adopted part way through MOI; those files have names of
the form TSCnnnnn.SCK, where nnnnn is a sequence number
beginning with 00001 and the file with the highest number
is the most recent. The value of nnnnn is set by NAIF.
Planetary Constants files were produced by the JPL/PDS
Navigation Ancillary Information Facility (NAIF) for use
with NAIF-developed and MGS-provided software. These are
ASCII files of variable length records. Each record is
delimited by an ASCII carriage-return (ASCII 13)
line-feed pair (ASCII 10), which may need to be
converted to either or before the file is used
on the local machine. File names have the form PCKydddC.TPC
where y is the one-digit year of the file creation date,
ddd is the day-of-year of the file creation date, and C
is a character denoting sequence when more than one file
with the same yddd is handled. C starts from 'A'
and progresses to 'B', 'C', etc. with increasing numbers
of similar coverage files.
Leapsecond files were produced by the JPL/PDS
Navigation Ancillary Information Facility (NAIF) for use
with NAIF-developed and MGS-provided software. These are
ASCII files of variable length records. Each record is
delimited by an ASCII carriage-return (ASCII 13)
line-feed pair (ASCII 10), which may need to be
converted to either or before the file is used
on the local machine. File names have the form LSKydddC.TLS
where y is the one-digit year of the file creation date,
ddd is the day-of-year of the file creation date, and C
is a character denoting sequence when more than one file
with the same yddd is handled. C starts from 'A'
and progresses to 'B', 'C', etc. with increasing numbers
of similar coverage files.
Channel Conversion Language files come in three types --
source, dependency, and binary. File names are of the
forms CCLydddS.SRC, CCLydddD.BIN, and CCLydddB.BIN,
respectively, where y is the one-digit year of the file
creation date and ddd is the day-of-year of the file
creation date. Source files are ASCII files of variable
length records. Each record is delimited by an ASCII
carriage-return (ASCII 13) line-feed pair (ASCII
10), which may need to be converted to either or
before the file is used on the local machine. Dependency and
binary files are identical to those used on the SOPC. Source
and binary files are typically 500 kB; dependency files are
typically 15 kB. Channel Conversion Language files are used
in converting raw binary data in telemetry streams to
meaningful numbers.
Channel Parameter Table files come in two types -- source and
binary. File names are of the forms CPTydddS.SRC and
CCLydddB.BIN, respectively, where y is the one-digit year
of the file creation date and ddd is the day-of-year of the
file creation date. Source files are ASCII files of variable
length records. Each record is delimited by an ASCII
carriage-return (ASCII 13) line-feed pair (ASCII
10), which may need to be converted to either or
before the file is used on the local machine. Binary files
are identical to those used on the SOPC. Source and binary
files are typically less than 1 MB. Channel Parameter Table
files are used in converting raw binary data in telemetry
streams to meaningful numbers.
Template Description Language files come in two types --
source and binary. File names are of the forms TDLydddS.SRC
and TDLydddB.BIN, respectively, where y is the one-digit
year of the file creation date and ddd is the day-of-year
of the file creation date. Source files are ASCII files of
variable length records. Each record is delimited by an
ASCII carriage-return (ASCII 13) line-feed pair
(ASCII 10), which may need to be converted to either
or before the file is used on the local machine. Binary
files are identical to those used on the SOPC. Source and
binary files are typically less than 1 MB. Template
Description Language files are used during display of data on
the SOPC.
Decommutation Map files come in two types -- source and
binary. File names are of the forms DCSxxxxx.SRC and
DCOxxxxx.BIN, respectively, where xxxxx is a mnemonic for
the map. Source files are ASCII files of variable length
records. Each record is delimited by an ASCII carriage-
return (ASCII 13) line-feed pair (ASCII 10), which
may need to be converted to either or before the
file is used on the local machine. Binary files are identical
to those used on the SOPC. Source and binary files are
typically less than 200 kB. Decommutation Map files are used
in converting raw binary packet data to channelized formats.
On the SOPC, they are used with the MGS-provided program
mapx.
NB: CCL, CPT, TDL, and decommutation files were used with
software provided by the MGS project to extract and scale
'engineering' data from spacecraft and ground DSN systems.
In early 2007 a combined software/hardware upgrade mandated
by JPL left Stanford unable to process these telemetry
streams absent a significant recovery effort. Since the
spacecraft had gone silent three months earlier, it was
decided not to make the investment. Thus Stanford is no
longer able to extract these engineering data from ECH and
MCH binary files (see below). It is likely that other users
of the data would find this task to be equally challenging.
However, the CSV*.ECH, CSV*.MCH, ECS, and ECT files are
ASCII and should represent the most likely engineering
channels to be of interest to radio science.
Angular Momentum Desaturation Files (AMD Directory)
---------------------------------------------------
Angular Momentum Desaturation files were produced by the MGS
Spacecraft Team (SCT). Each AMD file documents a set of AMD
events on the spacecraft. These are ASCII files of variable
length records. Each record is delimited by an ASCII
carriage-return (ASCII 13) line-feed pair (ASCII
10), which may need to be converted to either or
before the file is used on the local machine. File names
have the form ydddeeeC.AMD where y is the one-digit year
of the first data in the file, ddd is the day-of-year of
the first data in the file, eee is the day-of-year of the
last data in the file, and C is a character denoting
sequence when more than one file with the same ydddeee
is handled. C starts from 'A' and progresses to 'B', 'C',
etc. with increasing numbers of similar coverage files.
Each AMD file is accompanied by a PDS minimal label with file
name ydddeeeC.LBL. Typical file sizes are less than 1500
bytes.
Channelized Engineering Data Files (ECH Directory)
---------------------------------------------------
Channelized Engineering Data files were produced by the MGS
query server, operating on telemetry packets stored in the
MGS Central Data Base (CDB). These are binary files, usually
representing the collection of raw spacecraft engineering
data received from a 24 hour period; they are not readily
interpretable by end users. File names have the form
ydddeeeC.ECH where y is the one-digit year
of the first data in the file, ddd is the day-of-year of
the first data in the file, eee is the day-of-year of the
last data in the file, and C is a character denoting
sequence when more than one file with the same ydddeee
is handled. C starts from 'A' and progresses to 'B', 'C',
etc. with increasing numbers of similar coverage files.
Each ECH file is accompanied by a PDS minimal label with file
name ydddeeeC.LBL. File sizes can be as large as 200 MB.
In general, an ECH file can be derived from the corresponding
EPK file using MGS-provided software and a decommutation map.
Also in some ECH directories are ASCII tables of extracted
channel values--channelized state vectors, or CSV files.
These are values for a limited number of potentially
useful ECH channels that have been saved in tabular form.
CSV files in the ECH directory have names of the form
CSVydddC.ECH where y, ddd, and C are the same as for
the corresponding ECH file. Each CSV file is accompanied
by a detached PDS label with name CSVydddC.LBL which
completely describes the format and content of the CSV file.
NB: Stanford is no longer able to process binary ECH files;
see note above at the end of the section 'Files in the CALIB
Directory' for details.
Engineering Channelized Data Summary Files (ECS Directory)
---------------------------------------------------
Engineering Channelized Summary Data Files were created at
Stanford during ingestion of spacecraft engineering data.
Each file contains a summary line for each channel processed
from the previous day's telemetry. The ECS file thus gives
a snapshot (mean and standard deviation) of each channel
on each day. ECS files are PDS TABLE objects; each is
fully described as to format and content by a detached PDS
label. File names are of the form ydddeeeC.ECS where
y is the one-digit year of the first data, ddd is the
three-digit day-of-year of the first data, eee is the
three-digit day-of-year of the last data, and C is a
character denoting sequence when more than one file with
the same ydddeee is handled. File sizes vary depending
on the number of channels processed; typical growth is
4000 bytes per day.
Engineering Channel Table Files (ECT Directory)
---------------------------------------------------
Engineering Channel Table Data Files are created at Stanford
during ingestion of spacecraft engineering data. Each ECT
file is an ASCII table of time-ordered values from a single
spacecraft engineering channel, and each file is fully
described by a detached PDS label. File names are of the
form XXXydddC.ECT where XXX is a unique identifier for
the engineering channel, y is the one-digit year of the
first data, ddd is the three-digit day-of-year of the first
data, and C is a character denoting sequence when more
than one file with the same yddd is handled. File sizes
vary depending on the rate at which a channel was sampled;
they are typically under 100 kB. The detached label has
file name XXXydddC.LBL.
Experimenters Notebook Files (ENB Directory)
--------------------------------------------
Experimenters Notebook files are e-mail messages and other
notes collected during and shortly after data acquisition.
They document expectations of various measurements and
anomalies discovered in subsequent analysis. File names
have the form ENByyddd.TXT, where yy is the two-digit
year and ddd is the three-digit day-of-year. In general
the messages in file ENByyddd.TXT refer to activities on
that date regardless of when the message was sent. These
are ASCII files with variable length records. Each record
is delimited by an ASCII carriage-return line-feed pair.
Earth Orientation Parameter Files (EOP Directory)
---------------------------------------------------
Earth Orientation Parameter files were produced by the Time
and Earth Motion Precision Observation (TEMPO) Group at JPL.
They documented and predicted Earth rotation (rate and axis).
These are ASCII files of variable length records. Each
record is delimited by an ASCII line-feed (ASCII 10).
File names have the form ydddzeee.EOP where y is
the one-digit year of the first data in the file, ddd is
the day-of-year of the first data in the file, z is the
one-digit year of the last data, and eee is the day-of-year
of the last data in the file. EOP files were typically
released on Tuesdays and Fridays. There are both 'long'
and 'short' versions. The long file covered past motion
since about 1962 and a prediction for about three months into
the future; these files have typical sizes of 860 kB. The
short file covered the most recent nine months of past motion
and a prediction for three months into the future; these
files are typically 30 kB. Each EOP file is accompanied
by a PDS minimal label with file name ydddzeee.LBL.
Engineering Packet Data Files (EPK Directory)
---------------------------------------------------
Engineering Packet Data files were produced by the MGS
query server, operating on telemetry packets stored in the
MGS Central Data Base (CDB). These are binary files, usually
representing the collection of raw spacecraft engineering
data received from a 24 hour period; they are not readily
interpretable by end users. File names have the form
ydddeeeC.EPK where y is the one-digit year
of the first data in the file, ddd is the day-of-year of
the first data in the file, eee is the day-of-year of the
last data in the file, and C is a character denoting
sequence when more than one file with the same ydddeee
is handled. C starts from 'A' and progresses to 'B', 'C',
etc. with increasing numbers of similar coverage files.
Each EPK file is accompanied by a PDS minimal label with file
name ydddeeeC.LBL. File sizes can be as large as 100 MB.
NB: No EPK files were collected during MOI.
Filtered Body Rate Files (FBR Directory)
---------------------------------------------------
Filtered Body Rate Files were created at Stanford from
body rate data in the spacecraft engineering telemetry
stream. They give spacecraft attitude as a function of
time. FBR files are PDS TABLE objects; each is
fully described as to format and content by a detached PDS
label. File names are of the form ydddeeeC.FBR where
y is the one-digit year of the first data, ddd is the
three-digit day-of-year of the first data, eee is the
three-digit day-of-year of the last data, and C is a
character denoting sequence when more than one file with
the same ydddeee is handled. File sizes vary depending
on the time interval covered. FBR files were created
during MGS Cruise to support gravitational wave
experiments (GWE); as of the end of MOI, there was no
plan to generate them to support MOI analyses.
NB: No FBR files were collected during MOI.
GEODYN Trajectory Files (GDN Directory)
---------------------------------------------------
GEODYN SPK files were quick look orbit reconstructions
produced by the MOLA Precise Orbit Determination Team. They
were used for preliminary analysis of MOLA data and some radio
occultations. These files give spacecraft and planetary
ephemerides and are identical in format to SPK files (see
below) by the MGS NAV Team. Files with ORIGINAL_PRODUCT_ID
including 'qlnn' were based on the following gravity models:
ql15 mgm0989a
ql16 mgm0989c
ql17 gmm2b (with no one-way Doppler daya)
ql18 gmm2b (with one-way Doppler data if available)
These are ASCII files of variable
length records in a special NAIF 'transfer' format. Each
record is delimited by a carriage-return (ASCII 13) line-feed
(ASCII 10) pair, which may need to be removed before the
file is used on the local machine. After delimiter conversion
(if needed) the file would ordinarily be passed through the
NAIF utility SPACIT or TOBIN to convert it to the local
binary format. File names have the form ydddeeeC.GDN where
y is the one-digit year of the first data in the file, ddd
is the day-of-year of the first data in the file, eee is the
day-of-year of the last data in the file, and C is a
character denoting sequence when more than one file
with the same ydddeee is handled. C starts from 'A' and
progresses to 'B', 'C', etc. with increasing numbers of
similar coverage files. Each GDN file is accompanied by a
PDS minimal label with file name ydddeeeC.LBL. Typical file
sizes are less than 5 MB.
GEODYN Trajectory Files (GDF Directory)
---------------------------------------------------
GDF files are the same as GDN files (above) except that they
are considered 'final' versions of the orbits. File names
end with the .GDF suffix.
NB: No GDF files were collected during MOI.
Daily Health Report Files (HEA Directory)
---------------------------------------------------
Daily Health Report Files were created at Stanford; they
summarize spacecraft engineering data of interest for Radio
Science, list recently acquired radio data, summarize any
analysis performed on recent radio data, summarize anomalies
in recent radio science operations, and list files that have
been obtained from the MGS CDB or other sources. Daily
Health Report Files are PDS TEXT objects; each has an
attached PDS label. File names are of the form HEAydddC.TXT
where y is the one-digit year of the report, ddd is the
three-digit day-of-year of the report, and C is a
character denoting sequence when more than one file with
the same ydddeee is generated. The first report on a day
would be HEAydddA.TXT; subsequent revisions or updates
would be HEAydddB.TXT, HEAydddC.TXT, etc.
Some Health Reports are accompanied by plots, saved as
Type 1 PostScript files. File names for these plot files
have names of the form HEAydddC.PSn where y and ddd
are as defined above and n is the figure number.
Each PostScript file should be accompanied by a detached
PDS label, but that requirement was met only once in the
MOI data set. The label file has name HEAydddC.LBL,
meaning that the value of n is limited to 1 for any
single health report.
Both Health Reports themselves and accompanying PostScript
files have variable length records delimited by carriage-
return (ASCII 13) line-feed (ASCII 10) pairs.
Ionosphere Calibration Files (ION Directory)
---------------------------------------------------
Ionosphere Calibration files were produced by the Tracking
System Analytic Calibration (TSAC) Group at JPL. They
documented and predicted Earth ionospheric conditions.
These are ASCII files of variable length records. Each
record is delimited by an ASCII line-feed (ASCII 10).
File names have the form ydddeeeC.ION where y is
the one-digit year of the first data in the file, ddd is
the day-of-year of the first data in the file, eee is the
day-of-year of the last data in the file, and C is a
character denoting sequence when more than one file with the
same ydddeee is handled. C starts from 'A' and progresses
to 'B', 'C', etc. with increasing numbers of similar coverage
files. ION files were usually released at one week
intervals to cover a single month; ydddeeeA.ION would be
the file released during the first week, ydddeeeB.ION would
be the file released during the second week, etc. Each ION
file is accompanied by a PDS minimal label with file name
ydddeeeC.LBL. Typical file sizes are less than 50 kB.
Light Time Files (LIT Directory)
---------------------------------------------------
Light Time files were produced by the MGS Navigation Team
(NAV). They gave radio propagation time from the spacecraft
to Earth vs time. These are ASCII files of fixed
length records. Each record is delimited by an ASCII
carriage-return (ASCII 13) line-feed pair (ASCII
10), which may need to be converted to either or
before the file is used on the local machine. File names
have the form ydddeeeC.LIT where y is the one-digit year
of the first data in the file, ddd is the day-of-year of
the first data in the file, eee is the day-of-year of the
last data in the file, and C is a character denoting
sequence when more than one file with the same ydddeee
is handled. C starts from 'A' and progresses to 'B', 'C',
etc. with increasing numbers of similar coverage files.
Each LIT file is accompanied by a PDS minimal label with file
name ydddeeeC.LBL. Typical file sizes are less than 1 MB.
Channelized DSN Monitor Data Files (MCH Directory)
---------------------------------------------------
Channelized DSN Monitor Data files were produced by the MGS
query server, operating on DSN Monitor packets stored in the
MGS Central Data Base (CDB). These are binary files, usually
representing the collection of DSN Monitor data received from
a 24 hour period; they are not readily interpretable by end
users. File names have the form ydddeeeC.MCH where y is
the one-digit year of the first data in the file, ddd is
the day-of-year of the first data in the file, eee is the
day-of-year of the last data in the file, and C is a
character denoting sequence when more than one file with the
same ydddeee is handled. C starts from 'A' and progresses
to 'B', 'C', etc. with increasing numbers of similar coverage
files. Each MCH file is accompanied by a PDS minimal label
with file name ydddeeeC.LBL. File sizes can be as large as
30 MB. In general, an MCH file can be derived from the
corresponding MPK file using MGS-provided software and a
decommutation map. Monitor data are collected according to
MST (Monitor Sample Time) measured in UTC.
Also in some MCH directories are ASCII tables of extracted
channel values--channelized state vectors, or CSV files.
These are values for a limited number of potentially
useful MCH channels that have been saved in tabular form.
CSV files in the MCH directory have names of the form
CSVydddC.MCH where y, ddd, and C are the same as for
the corresponding MCH file. Each CSV file is accompanied
by a detached PDS label with name CSVydddC.LBL which
completely describes the format and content of the CSV file.
NB: Stanford is no longer able to process binary MCH files;
see note above at the end of the section 'Files in the CALIB
Directory' for details.
Maneuver Implementation/Reconstruction Files (MIF Directory)
---------------------------------------------------
Maneuver Implementation/Reconstruction files were produced by
the MGS Spacecraft Team (SCT); they documented spacecraft
maneuver events. These are ASCII files of variable length
records. Each record is delimited by an ASCII line-feed
(ASCII 10). File names have the form ydddeeeC.MIF where y
is the one-digit year of the first data in the file, ddd is
the day-of-year of the first data in the file, eee is the
day-of-year of the last data in the file, and C is a
character denoting sequence when more than one file with the
same ydddeee is handled. C starts from 'A' and progresses
to 'B', 'C', etc. with increasing numbers of similar coverage
files. Each MIF file is accompanied by a PDS minimal label
with file name ydddeeeC.LBL. Typical file sizes are 2327
bytes.
Maneuver Performance Data Files (MPD Directory)
---------------------------------------------------
Maneuver Performance Data files were produced by the MGS
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.
Each record is delimited by an ASCII line-feed
(ASCII 10). File names have the form ydddeeeC.MPD where
y is the one-digit year of the first data in the file,
ddd is the day-of-year of the first data in the file, eee
is the day-of-year of the last data in the file, and C is
a character denoting sequence when more than one file with
the same ydddeee is handled. C starts from 'A' and
progresses to 'B', 'C', etc. with increasing numbers of
similar coverage files. Each MPD file is accompanied by a
PDS minimal label with file name ydddeeeC.LBL. Typical
file sizes are 4 kB.
Maneuver Profile Files (MPF Directory)
---------------------------------------------------
Maneuver Profile Files were produced by the MGS Navigation
Team (NAV). They are generic descriptions of orbit
adjustments used by MGS during aerobraking. These are ASCII
files of variable length records. Each record is delimited
by a carriage-return (ASCII 13) line-feed
(ASCII 10) pair. File names have the form XnnnDDCC.MPF
where X is a character, nnn is a 3-digit number, DD
indicates the adjustment direction ('UP' or 'DN'), and
CC indicates the sequence if there is more than one file
with the same XnnnDD. CC starts from 'AA'. Each MPF
is accompanied by a PDS minimal label with file name
XnnnDDCC.LBL. Typical file sizes are less than 700 bytes.
DSN Monitor Packet Data Files (MPK Directory)
---------------------------------------------------
DSN Monitor Packet Data files were produced by the MGS
query server, operating on DSN Monitor packets stored in the
MGS Central Data Base (CDB). Monitor data are records of
DSN status and radio measurements. These are binary files,
data received from a 24 hour period; they are not readily
interpretable by end users. File names have the form
ydddeeeC.MPK where y is the one-digit year
of the first data in the file, ddd is the day-of-year of
the first data in the file, eee is the day-of-year of the
last data in the file, and C is a character denoting
sequence when more than one file with the same ydddeee
is handled. C starts from 'A' and progresses to 'B', 'C',
etc. with increasing numbers of similar coverage files.
Each MPK file is accompanied by a PDS minimal label with file
name ydddeeeC.LBL. File sizes can be as large as 30 MB.
NB: No MPK files were collected during MOI.
Orbit Propagation and Time Generation Files (OPT Directory)
---------------------------------------------------
Orbit Propagation and Time Generation files were produced by
the MGS Navigation Team (NAV). They contain estimates of
event timing (e.g., equator crossings) that depend on
precise knowledge of the spacecraft orbit. These are ASCII
files of variable length records. Each record is delimited
by an ASCII line-feed (ASCII 10). File names
have the form ydddeeeC.OPT where y is the one-digit year
of the first data in the file, ddd is the day-of-year of
the first data in the file, eee is the day-of-year of the
last data in the file, and C is a character denoting
sequence when more than one file with the same ydddeee
is handled. C starts from 'A' and progresses to 'B', 'C',
etc. with increasing numbers of similar coverage files.
Each OPT file is accompanied by a PDS minimal label with file
name ydddeeeC.LBL. Typical file sizes are less than 100 kB.
Typical OPT files during MOI included one day of orbit
reconstructions followed by several days of orbit
predictions.
Solar Array Kernel Files (SAK Directory)
---------------------------------------------------
Solar Array Kernel files were produced by the MGS Spacecraft
Team (SCT). They give the attitude of each solar array
panel as a function of time. These are ASCII files of
variable length records in a special NAIF 'transfer' format.
Each record is delimited by a carriage-return (ASCII 13)
line-feed (ASCII 10) pair, which may need to be
removed before the file is used on the local machine.
After delimiter conversion (if needed) the file would
ordinarily be passed through the NAIF utility SPACIT or
TOBIN to convert it to the local binary format. File names
have the form ydddeeeC.TCK where y is the one-digit year
of the first data in the file, ddd is the day-of-year of
the first data in the file, eee is the day-of-year of the
last data in the file, and C is a character denoting
sequence when more than one file with the same ydddeee
is handled. C starts from 'A' and progresses to 'B', 'C',
etc. with increasing numbers of similar coverage files.
Each TCK file is accompanied by a PDS minimal label with
file name ydddeeeC.LBL. Typical file sizes are less than
5 MB.
Space Flight Operation Schedule Files (SFO Directory)
---------------------------------------------------
Space Flight Operations Schedule Files were produced by the
MGS Mission Control Team (MCT), usually in parallel with
a corresponding Sequence of Events (SOE) file. They
graphically present parts of the SOE. These are
ASCII files of variable length records in a special format
that allows use with the MGS-provided sfosedt program.
Each record is delimited by a carriage-return (ASCII 13)
line-feed (ASCII 10) pair, which may need to be removed
before the file is used on the local machine. File names
have the form ydddeeeC.SFO where y is the one-digit year
of the first data in the file, ddd is the day-of-year of
the first data in the file, eee is the day-of-year of the
last data in the file, and C is a character denoting
sequence when more than one file with the same ydddeee is
handled. C starts from 'A' and progresses to 'B', 'C', etc.
with increasing numbers of similar coverage files. Each SFO
file is accompanied by a PDS minimal label with file name
ydddeeeC.LBL. Typical file sizes are less than 100 kB.
NB: No SFO files were produced after 1998-08-20.
Sequence of Events Files (SOE Directory)
---------------------------------------------------
Sequence of Events Files were produced by the MGS Mission
Control Team (MCT). These are ASCII files of variable length
records. Until 1998-08-20 SOE files were produced in a
special format that allowed use with the MGS-provided soeedt
program. After 1998-08-20, files were produced in a straight
ASCII format that required no special software; these may be
identified by the '.tsoe' suffix in the ORIGINAL_PRODUCT_ID.
Each record is delimited by a carriage-return (ASCII 13)
line-feed (ASCII 10) pair, which may need to be removed
before the file is used on the local machine. File names
have the form ydddeeeC.SOE where y is the one-digit year
of the first data in the file, ddd is the day-of-year of
the first data in the file, eee is the day-of-year of the
last data in the file, and C is a character denoting
sequence when more than one file with the same ydddeee is
handled. C starts from 'A' and progresses to 'B', 'C',
etc. with increasing numbers of similar coverage files.
Each SOE file is accompanied by a PDS minimal label with
file name ydddeeeC.LBL. Typical file sizes are less than
1 MB.
Spacecraft/Planetary Ephemeris (SPK) Files (SPK Directory)
---------------------------------------------------
Spacecraft/Planetary Ephemeris Files (also known as SP
kernels or SPK files) were produced by the MGS Navigation Team
(NAV). These files give spacecraft and planetary ephemerides.
These are ASCII files of variable length records in
a special NAIF 'transfer' format. Each record is delimited
by a carriage-return (ASCII 13) line-feed (ASCII 10)
pair, which may need to be removed before the file is used on
the local machine. After delimiter conversion (if needed)
the file would ordinarily be passed through the NAIF utility
SPACIT or TOBIN to convert it to the local binary format.
File names have the form ydddeeeC.SPK where y is the
one-digit year of the first data in the file, ddd is the
day-of-year of the first data in the file, eee is the
day-of-year of the last data in the file, and C is a
character denoting sequence when more than one file
with the same ydddeee is handled. C starts from 'A' and
progresses to 'B', 'C', etc. with increasing numbers of
similar coverage files. Each SPK file is accompanied by a
PDS minimal label with file name ydddeeeC.LBL. Typical file
sizes are less than 5 MB. Typical SPK files during MOI
included one day of orbit reconstructions followed by several
days of orbit predictions.
Spacecraft Attitude (CK) Files (TCK Directory)
---------------------------------------------------
Spacecraft Attitude Files (also known as C kernels or CK
files) were produced by the MGS Spacecraft Team (SCT).
These are ASCII files of variable length records in
a special NAIF 'transfer' format. Each record is delimited
by a carriage-return (ASCII 13) line-feed (ASCII 10)
pair, which may need to be removed before the file is used on
the local machine. After delimiter conversion (if needed)
the file would ordinarily be passed through the NAIF utility
SPACIT or TOBIN to convert it to the local binary format.
File names have the form ydddeeeC.TCK where y is the
one-digit year of the first data in the
file, ddd is the day-of-year of the first data in the file,
eee is the day-of-year of the last data in the file, and C
is a character denoting sequence when more than one file
with the same ydddeee is handled. C starts from 'A' and
progresses to 'B', 'C', etc. with increasing numbers of
similar coverage files. Each TCK file is accompanied by a
PDS minimal label with file name ydddeeeC.LBL. Typical file
sizes are less than 5 MB.
Troposphere Calibration Files (TRO Directory)
---------------------------------------------------
Troposphere Calibration files were produced by the
Tracking System Analytic Calibration (TSAC) Group at JPL.
They documented and predicted Earth tropospheric conditions.
These are ASCII files of variable length records. Each
record is delimited by an ASCII line-feed (ASCII 10).
File names have the form ydddeeeC.TRO where y is
the one-digit year of the first data in the file, ddd is
the day-of-year of the first data in the file, eee is the
day-of-year of the last data in the file, and C is a
character denoting sequence when more than one file with the
same ydddeee is handled. C starts from 'A' and progresses
to 'B', 'C', etc. with increasing numbers of similar coverage
files. TRO files were typically released at the beginning of
a month and covered the previous month. Each TRO file is
accompanied by a PDS minimal label with file name
ydddeeeC.LBL. Typical file sizes are less than 50 kB.
UltraStable Oscillator Files (USO Directory)
--------------------------------------------
UltraStable Oscillator (USO) files are calibration data
derived from open-loop radio measurments. Files are PDS
table objects with detached labels. Examples include USO
Allan Deviation (type A files) and the piecewise-continuous
linear model of USO frequency (type M files). File names
are of the form USOtyddd.TAB, where t is the file type
(see above), y is the one-digit year in which the file was
created, and ddd is the three-digit day-of-year in which
the file was created. Each USO file is accompanied by a
detached PDS label with name USOtyddd.LBL which completely
describes the content and format of the file.
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. Each record is delimited
by an ASCII line-feed (ASCII 10). File names have
the form ydddeeeD.WEA where y is the one-digit year of
the first data in the file, ddd is the day-of-year of the
first data in the file, eee is the day-of-year of the last
data in the file, and D is a single digit denoting the
DSN complex at which the data were acquired ('1' for
Goldstone, '4' for Canberra, or '6' for Madrid). 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
ydddeeeC.LBL. The files grow at the rate of approximately
90 kB per month.
Coordinate System
=================
SPK ephemeris files and TCK files were produced for the
J2000 inertial reference frame until the second orbit after
Mars Orbit Insertion, when the TCK files were referenced to
the Mars Mean Equator frame. SAK files presumably follow the
same format as TCK files. NAIF reader routines may be
used to convert these to other coordinate systems.
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 Stanford University and elsewhere.
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
============
The archival data set is written on CD-WO media using the
Young Minds CD Studio or Yamaha/GEAR authoring system. The
CD-WO volumes conform to ISO 9660 standards.
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