PDS_VERSION_ID = PDS3
RECORD_TYPE = STREAM
SPACECRAFT_NAME = "MARS GLOBAL SURVEYOR"
TARGET_NAME = "MARS"
OBJECT = TEXT
INTERCHANGE_FORMAT = ASCII
PUBLICATION_DATE = 1998-11-09
END_OBJECT = TEXT
END
Mars Orbital Camera
Software Interface Specification
MOC Narrow Angle and Wide Angle
Decompressed Standard Data Products
M. Caplinger
Malin Space Science Systems, Inc.
Approved by:
_________________________
M. Malin, Principal Investigator
September 1998
(formatted December 29, 1998)
Contents
1. Introduction ...................................... 1
1.1. Purpose ........................................ 1
1.2. Scope .......................................... 1
1.3. Applicable Documents ........................... 1
1.4. Functional Description ......................... 1
1.4.1. Data Content Summary ........................ 1
1.4.2. Source and Transfer Method .................. 2
1.4.3. Recipients and Utilization .................. 2
1.4.4. Pertinent Relationships with Other Inter-
faces ............................................ 2
1.5. Assumptions and Constraints .................... 2
2. Environment ....................................... 3
2.1. Hardware Characteristics and Limitations ....... 3
2.1.1. Special Equipment and Device Interfaces ..... 3
2.1.2. Special Setup Requirements .................. 3
2.2. Interface Medium Characteristics ............... 3
2.3. Failure Protection, Detection, and Recovery .... 3
2.4. End-of-File Conventions ........................ 3
3. Access ............................................ 3
3.1. Access Tools ................................... 3
3.2. Input/Output Protocols ......................... 3
3.3. Timing and Sequencing Characteristics .......... 3
3.4. PDB Information ................................ 3
4. Detailed Interface Specifications ................. 4
4.1. Labeling and Identification .................... 4
4.2. Structure and Organization Overview ............ 4
4.3. Substructure Definition and Format ............. 5
4.3.1. Header/Trailer Description Details .......... 9
4.4. Volume, Size, and Frequency Estimates .......... 9
September 1998 iii
1. Introduction
_ ____________
1.1. Purpose
_ _ _______
This document describes the format of the Mars Orbiter Cam-
era (MOC, previously known as the Mars Observer Camera)
Decompressed Standard Data Product for the Narrow Angle (NA)
and Wide Angle (WA) systems.
Note that this product is explicitly not called an Experi-
ment Data Record (EDR), because it has undergone more pro-
cessing (decompression and error correction) than an EDR
traditionally sees. The closest thing to an EDR product
which will be archived are the raw MOC instrument packets.
1.2. Scope
_ _ _____
The format and content specifications in this SIS apply to
all phases of the project for which this product is avail-
able.
1.3. Applicable Documents
_ _ __________ _________
Mars Global Surveyor Science Data Management Plan (JPL 542-
310)
Mars Global Surveyor Project Archive Generation, Validation
and Transfer Plan (JPL 542-312)
Mars Global Surveyor Project Data Management Plan (JPL 542-
403)
Mars Observer Camera Software User's Guide (Part 1: Flight
Software)
Mars Observer Camera Instrument Template (I-Kernel PDS docu-
ment)
Mars Observer Project Archive Policy and Data Transfer Plan,
642-447.
Planetary Science Data Dictionary Document, PDS Version 2.0,
May 1991.
Margaret Cribbs, "Comments on the MOC label", IOM# 361-92-
MAC016, 2 April 1992.
1.4. Functional Description
_ _ __________ ___________
1.4.1. Data Content Summary
_ _ _ ____ _______ _______
Each MOC Decompressed Standard Data Product is a single
image in decompressed format.
September 1998 1
The only formatting differences between Narrow and Wide
Angle products are the maximum possible width of the image
(2048 for the Narrow Angle and 3456 for the Wide Angle) and
the presence or values of some of the keywords; the products
are otherwise formatted identically.
1.4.2. Source and Transfer Method
_ _ _ ______ ___ ________ ______
MOC products are produced by the `makepds' program from the
format internally used at the MOC Mission Operations Facil-
ity (MOF). This program reads a raw image file (see the MOC
Software User's Guide), extracts some information from its
headers, formats and attaches the PDS labels, and appends
the image data.
It is expected that there will be three ways to receive MOC
products: by electronic file transfer from the MOC MOF, by
electronic file transfer from the Project Database, and on
some archival medium such as CD-ROM.
1.4.3. Recipients and Utilization
_ _ _ __________ ___ ___________
These products will be available to MOC team members, the
Mars Global Surveyor science community, the planetary sci-
ence community, and other interested parties. Descriptions
of data rights and proprietary periods are beyond the scope
of this document, and are discussed in the Mars Global Sur-
veyor Project Archive Policy and Data Transfer Plan, and in
unique Operational Interface Agreements between the MOC Sci-
ence Team and other parties.
These products will be used for engineering support, direct
science analysis, or the construction of other science pro-
ducts.
1.4.4. Pertinent Relationships with Other Interfaces
_ _ _ _________ _____________ ____ _____ __________
See the MOC Software User's Guide for descriptions of other
interfaces.
1.5. Assumptions and Constraints
_ _ ___________ ___ ___________
Note that this file contains decompressed image data. It is
a raw image that is not corrected for instrument signature,
effects of spacecraft motion, or the effects of imaging
geometry. Although there is enough information in the
header to do some processing, for more sophisticated pro-
cessing ancillary files will be required. These ancillary
files are not described in this document. Every effort will
be made to insure that this ancillary information will be
conveniently accessible to users of MOC products (for exam-
ple, it may be included on the same CDROM volumes as the
data products themselves.) Examples of ancillary files are
September 1998 2
calibration files, viewing geometry files (e.g., SPICE ker-
nels), image index tables, etc.
2. Environment
_ ___________
2.1. Hardware Characteristics and Limitations
_ _ ________ _______________ ___ ___________
2.1.1. Special Equipment and Device Interfaces
_ _ _ _______ _________ ___ ______ __________
Interfaces to access either CD-ROM volumes or electronic
file transfer are described elsewhere; for example, see TBD.
2.1.2. Special Setup Requirements
_ _ _ _______ _____ ____________
None.
2.2. Interface Medium Characteristics
_ _ _________ ______ _______________
2.3. Failure Protection, Detection, and Recovery
_ _ _______ __________ _________ ___ ________
Raw instrument telemetry will be archived in the PDB.
Depacketized compressed image data will be archived at the
MOC MOF.
2.4. End-of-File Conventions
_ _ ___ __ ____ ___________
End-of-file labeling shall comply with SFDU standards;
specifically, fixed-size records are used, the header expli-
citly contains the record offset of each subelement of the
dataset, and the size of each subelement can be computed
from information in the header.
3. Access
_ ______
3.1. Access Tools
_ _ ______ _____
Existing PDS image display programs can display these files.
3.2. Input/Output Protocols
_ _ _____ ______ _________
None identified.
3.3. Timing and Sequencing Characteristics
_ _ ______ ___ __________ _______________
None.
3.4. PDB Information
_ _ ___ ___________
These products can be retrieved using the standard PDB key-
words. (The keywords expected to be useful for retrieval
are FILE_NAME and START_TIME. A higher-level catalog may be
available but is beyond the scope of this document.)
September 1998 3
4. Detailed Interface Specifications
_ ________ _________ ______________
4.1. Labeling and Identification
_ _ ________ ___ ______________
The dataset ID is MGS-M-MOC-NA/WA-2-DSDP-L0-V1.0.
Each product will have a file name of the form "<id>.IMG",
where the ID is not to exceed 8 characters, will start with
an alphabetic character, and will consist only of
alphanumeric characters. For pre-mapping images, the id
will be of the form PPPNNNMM, where PPP is a mission phase
descriptor, NNN is the orbit number, and MM is the image of
that orbit. (For the mapping mission, the expected form
will be PPPIIIII, where PPP will be a three-character string
defining the mapping cycle, and IIIII will be an index
within the mapping cycle.) The file name will be unique
across all MOC data product files. Case is not significant;
under the Unix operating system, the names will be con-
sidered to be in all lower-case.
4.2. Structure and Organization Overview
_ _ _________ ___ ____________ ________
All MOC images must be a multiple of 16 pixels in both width
and height. Images are broken up into subimages (also
called fragments), and each fragment is transmitted
separately. Raw and predictively compressed images are
reconstructed by concatenating all of their image fragments
and then processing; transform compressed images are pro-
cessed a fragment at a time.
A MOC data product consists of one image with decompression
applied. In the event of data loss caused by packets
dropped in the space-to-earth link or in the ground segment
of the DSN, a standard first-order correction algorithm has
been applied. Selected MOC images may have had additional
corrections applied; this archive represents the best avail-
able reconstruction at the time of archive production.
PDS_VERSION_ID PDS3
FILE_NAME "filename"
RECORD_TYPE FIXED_LENGTH
RECORD_BYTES nnnn
FILE_RECORDS nn
LABEL_RECORDS nn
^IMAGE nn
SPACECRAFT_NAME MARS_GLOBAL_SURVEYOR
MISSION_PHASE_NAME AEROBRAKING-1; SPO-1; SPO-2; MAPPING
TARGET_NAME MARS
INSTRUMENT_ID MOC-NA or MOC-WA
PRODUCER_ID MGS_MOC_TEAM
DATA_SET_ID MGS-M-MOC-2-DSDP-L0-V1.0
PRODUCT_RELEASE_DATE yyyy-mm-ddThh:mm:ss.fff
September 1998 4
PRODUCT_CREATION_TIME yyyy-mm-ddThh:mm:ss.fff
SOFTWARE_VERSION "id-string"
UPLOAD_ID "version-id"
PRODUCT_ID "product-id"
START_TIME yyyy-mm-ddThh:mm:ss.fff
IMAGE_TIME yyyy-mm-ddThh:mm:ss.fff
STOP_TIME yyyy-mm-ddThh:mm:ss.fff
SPACECRAFT_CLOCK_START_COUNT "sclk-string"
SPACECRAFT_CLOCK_STOP_COUNT "N/A"
FOCAL_PLANE_TEMPERATURE ff.fff
GAIN_MODE_ID "gain-id"
OFFSET_MODE_ID "offset-id"
LINE_EXPOSURE_DURATION ff.fff
DOWNTRACK_SUMMING nn
CROSSTRACK_SUMMING nn
EDIT_MODE_ID "nnnn"
FILTER_NAME RED or BLUE
RATIONALE_DESC string
OBJECT IMAGE
LINES nnn
LINE_SAMPLES nnn
LINE_PREFIX_BYTES nnn
LINE_SUFFIX_BYTES nnn
SAMPLE_TYPE UNSIGNED_INTEGER
SAMPLE_BITS 8
SAMPLE_BIT_MASK 2#11111111#
CHECKSUM 16#xxxx#
END_OBJECT
END CCSD3...
4.3. Substructure Definition and Format
_ _ ____________ __________ ___ ______
PDS_VERSION_ID
The PDS version number for the header format; e.g.,
PDS3.
FILE_NAME
The file name for these products; see above.
RECORD_TYPE
The record type; always FIXED_LENGTH for these pro-
ducts.
RECORD_BYTES
The number of bytes per record. For these products,
the same as the LINE_SAMPLES field of the IMAGE object.
FILE_RECORDS
The total number of records in this file. The last
record will be padded with zeros if necessary.
September 1998 5
LABEL_RECORDS
The number of records used for header data. If needed,
the last record of the header will be padded with
blanks.
^IMAGE
Pointer to the starting record of the image object in
the file.
SPACECRAFT_NAME
Always MARS_GLOBAL_SURVEYOR.
MISSION_PHASE_NAME
Name of the mission phase; e.g., AEROBRAKING-1.
TARGET_NAME
The name of the target body; typically MARS.
PRODUCER_ID
Always MGS_MOC_TEAM.
DATA_SET_ID
Always MGS-M-MOC-2-DSDP-L0-V1.0.
PRODUCT_RELEASE_DATE
Date of this product's release to the Project Data
Base. This date does not imply the end of the
proprietary period.
PRODUCT_CREATION_TIME
Time and date of this file's creation. Note that this
time is the time of this file's creation in this for-
mat, and does not reflect the acquisition time or the
time of any other processing that may be associated
with this product.
SOFTWARE_VERSION
Identifier of the version of the MOC Ground Data System
software that created this product.
UPLOAD_ID
Identifier of version of the MOC flight software used
to acquire this image.
PRODUCT_ID
(This field replaces the earlier IMAGE_ID field.) This
uniquely identifies this MOC product among all MOC pro-
ducts. The MOC product ID format for pre-mapping is
xxx-ooo/nnn, where xxx is a mission phase string, ooo
is the orbit number and nnn is the image on that orbit;
e.g., SPO1-501/01. For the mapping mission, we expect
to use Mcc/nnnnn, where c is the mapping cycle number
and nnnnn is an index within that mapping cycle; e.g.,
September 1998 6
M01/12345.
START_TIME, IMAGE_TIME
SCET (UTC) time at start of image acquisition. These
two fields are always the same. (IMAGE_TIME is
included for compatibility with earlier non-MOC pro-
ducts.)
STOP_TIME
SCET (UTC) time at end of image acquisition. This is
redundant and can be computed from the start time, the
line clocking rate, and the number of lines.
SPACECRAFT_CLOCK_START_COUNT
Value of spacecraft clock at start of image acquisi-
tion. This is redundant with the above times, unless
there is an anomaly with the spacecraft clock. The
format of this field is compatible with the NAIF
Toolkit software (e.g., "00610499:32") There is no
corresponding STOP_COUNT because the timing of a MOC
image, once started, is independent of the spacecraft
clock.
The following information can be used, along with calibra-
tion files to be included on the volume, to calibrate each
image. This information is in some sense redundant with
that in the E-kernel (presumably a separate file on the
volume), but as of now, the E-kernel is still too ill-
defined to be a reliable source of information. See the MOC
I-kernel for more information on calibration.
FOCAL_PLANE_TEMPERATURE
Temperature of focal plane of optical system associated
with this image, in degrees Kelvin.
GAIN_MODE_ID
The MOC gain setting in hexadecimal.
OFFSET_MODE_ID
The MOC offset in integer steps of 5 DN.
LINE_EXPOSURE_DURATION
Per-line exposure duration in units of milliseconds.
The time a given line was acquired can be determined by
multiplying the line exposure time by the number of
previous lines and adding it to the image start time.
Note that the NA implements downtrack summing by
increasing the line time; for example, a 2X2 summed
image has an actual line time twice that given by this
field. Similarly, the gain is adjusted appropriately
for summed NA images; for example, a 2X2 summed image's
gain is reduced by a factor of 2.
September 1998 7
DOWNTRACK_SUMMING, CROSSTRACK_SUMMING
The MOC can do pixel averaging in the instrument before
transmission. For the NA, this must range from 1 (no
summing) to 8x summing, and downtrack and crosstrack
summing must be equal. For the WA, downtrack and
crosstrack summing range from 1 to 127, and can be dif-
ferent.
EDIT_MODE_ID
The edit mode is the first pixel of the CCD sampled for
the image acquisition, and thus specifies the off-nadir
look angle. For WA products, the special value 3456
indicates that the leading dark reference pixels were
acquired as the first eight pixels of each line; the
special value 3472 indicates that the trailing dark
reference pixels were acquired as the last eight pixels
of each line. For WA products, if dark pixels were
acquired and compression was enabled, the dark refer-
ence pixels are compressed and included in the data.
An EDIT_MODE_ID value of "0" refers to the first pixel
in the array.
FILTER_NAME
Either RED for the red Wide Angle or BLUE for the blue
Wide Angle. Does not appear for NA products.
RATIONALE_DESC
A text description of the scientific purpose for the
acquisition of this image; e.g., "Monthly monitoring of
aeolian features on summit of Pavonis Mons".
For some specific images, this string will contain a
description of the image as actually received; for routine
mapping operations, it will more likely be the goal of the
image as targeted (which may not be met if the image missed
its target significantly.)
The following describe keywords found internal to the IMAGE
object.
LINES
Number of lines in the image.
LINE_SAMPLES
Number of samples per line in the image.
LINE_PREFIX_BYTES
Number of bytes of prefix information per line. If
these bytes are present, they are the leading dark
reference pixel values.
LINE_SUFFIX_BYTES
Number of bytes of suffix information per line. If
September 1998 8
these bytes are present, they are the trailing dark
reference pixel values.
SAMPLE_TYPE
Type of each sample; for MOC, always UNSIGNED_INTEGER.
SAMPLE_BITS
Number of bits for each sample; for MOC, always 8.
SAMPLE_BIT_MASK
Bit mask description for each sample; for MOC, always
2#11111111#.
CHECKSUM
This is a checksum for the entire data part of the
image, to be used for data validation.
4.3.1. Header/Trailer Description Details
_ _ _ ______ _______ ___________ _______
See above. No trailers are present.
4.4. Volume, Size, and Frequency Estimates
_ _ ______ ____ ___ _________ _________
The total volume of MOC data to be returned is approximately
45 GBytes. Volume returned varies as a function of the
available data rate; see the Archive Policy and Data Manage-
ment Plan for more details.
It is not known what fraction of total MOC return will be
used for products of a particular type (e.g., NA or WA). It
is also not known what average amounts of compression will
be used, although a nominal value of 5:1 is expected.
September 1998 9