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Defense Meteorological Satellite Program (DMSP) Satellite F12 Source/Platform
Summary:
This document contains information about the DMSP F12 Satellite. The DMSP F12 satellite
is a in a near circular, sun synchronous, polar orbit. The DMSP mission is to provide global
visible and infrared cloud data and other specialized
meteorological, oceanographic and solar-geophysical data in support of world wide Department
of Defense (DoD) operations. A description of the mission is provided as
is information about the spacecraft and its environment. The ground data system
is briefly described.
Table of Contents:
Platform or Data Collection Environment
Overview
Platform or Data Collection Environment Long Name, Platform Acronym: Defense Meteorological Satellite Program (DMSP) Block 5D-2 Satellite F12, DMSP F12
Platform Introduction: DMSP, originally known as the Defense System Applications Program
(DSAP) and the Defense Acquisition and Processing Program (DAPP), is a long-term
USAF effort in space to monitor the meteorological, oceanographic and solar-geophysical
environment of the Earth in support of DoD operations. All spacecraft launched have
had a tactical (direct readout) and a strategic (stored data) capacity. In December
1972, DMSP data was declassified and made available to the civil/scientific community.
The USAF maintains an operational constellation of two near-polar, sun-synchronous satellites
Collection Environment: Satellite
Platform Program Management: The DMSP program office is located at the Space Systems Division, Air Force Material
Command, Los Angeles Air Force Station, Los Angeles, California 90009-2960. Funding is
provided by the Department of Defense (DoD).
Platform Mission Objectives: The DMSP mission is to provide global visible and infrared cloud data and other specialized
meteorological, oceanographic and solar-geophysical data in support of world wide Department
of Defense (DoD) operations.
Platform Parameters: DMSP Satellite F12 was built by General Electrics Astro-Space Division (now part of Martin
Marietta Astro Space). It was launched on August 29, 1994 from Vandenberg AFB,
California using an Atlas E rocket. The spacecraft is 3.7 meters in length with a diameter of
1.2 meters with an on-orbit mass of 831 kilograms. It has a design lifetime of 48 months.
Power is provided though a 9.29 sq-m solar cell panel. Attitude is controlled using momentum
wheels and magnetic coils using a strap-down star sensor and gyros as the reference.
Coverage Information: DMSP Satellite F12 is in a near circular, sun synchronous, polar orbit.
- Maximum Altitude: 851 km
- Minimum Altitude: 844 km
- Inclination: 98.9 deg
- Period: 102.0 minutes
- Eccentricity: 0.00123
- Ascending Equator Crossing Time (Local Time):
- At Launch: 21:22
- Current (09/02/95): 21:27
- Swath Width:
- Visible and Infrared Imagery - 3000 km
- Microwave Imagery - 1400 km
- Temperature Sounder - 1500 km
- Water Vapor Profiler - 1500 km
- Launch Date - August 29, 1994
- End Mission (Operational Support - F12 is currently (9/2/95) providing primary support with
sensors OLS, SSM/T, SSM/T-2, SSJ/4, SSIES2, SSM and SSB/X-2 still providing data.
Attitude Characteristics:
• Pointing Accuracy: 0.01 deg (primary), 0.12 deg (backup)
• Stability: maximum rate - 0.03 deg/sec per axis.
Short term changes in attitude are measured using three orthogonal gyroscopes. A strap down
star sensor is used to bound the effects of gyroscope drift. The desired attitude is computed
based upon a star catalog and an ephemeris table up-linked to the spacecraft daily. Three-axis
attitude control is maintained in the orbital configuration by automatic momentum exchange
between three momentum wheels. On-board magnetic coils provide controlled interaction with
the earth's magnetic field to prevent the accumulation of wheel secular momentum. Operations
of these coils is under control of the closed loop spacecraft attitude control system. Both the
momentum wheels and gyroscopes are backed up by a fourth skewed unit for redundancy.
Data Collection System: Data is transmitted in real time to tactical terminals world-wide. Data is also stored using on-board
recorders for transmission to and processing by the Air Force Global Weather Central
(AFGWC), Offutt AFB, Nebraska and the Fleet Numerical Meteorology and Oceanography
Center (FNMOC), Monterey, California. Both AFGWC and FNMOC relay the SSM/I, SSM/T and SSM/T2 data to the
National Environmental Satellite, Data, and Information System (NESDIS). AFGWC also sends
the entire data stream to the National Geophysical Data Center (NGDC).
Communication Links: DMSP uses S-band links at 1.024 Mbps for the tactical real time transmissions. Stored data are
transmitted at 2.66 Mbps to receiving sites at
- Fairchild AFB, Washington
- Thule, Greenland
- AF Remote Tracking Station, Hawaii and the
- New Hampshire Tracking Station
Data are then relayed at 3.072 Mbps via commercial geostationary communications satellite to AFGWC
and FNMOC. Spacecraft commanding is done at L-band at a 2 Kbps rate.
List of Sensors/Instruments:
- OLS - Operational Linescan System
- SSM/I
- Special Sensor Microwave Imager
- SSM/T - Special Sensor Microwave Temperature Sounder
- SSM/T2 - Special Sensor Microwave Water Vapor Profiler
- SSIES - Special Sensor Ion and Electron Scintillation Monitor
- SSJ/4 - Special Sensor Precipitating Electron and Ion Spectrometer
- SSB/X-2 - Special Sensor Gamma/X-Ray Detector
- SSM - Special Sensor Magnetomete
Ground Segment Information
Tracking and Control: DMSP satellite command and control is performed by the 6th Satellite Operations Group at
Offutt AFB, Nebraska.
Data Acquisition and Processing: Data is transmitted in real time to tactical terminals world-wide. Data is also stored using on-board
recorders for transmission to and processing by the Air Force Global Weather Central
(AFGWC), Offutt AFB, Nebraska and the Fleet Numerical Meteorology and Oceanography
Center (FNMOC), Monterey, California. Both AFGWC and FNMOC relay the SSM/I, SSM/T and SSM/T2 data to the
National Environmental Satellite, Data, and Information System (NESDIS). AFGWC also sends
the entire data stream to the National Geophysical Data Center (NGDC).
Latitude Crossing Times:
Ascending Equatorial Crossing Time (Local Time): At Launch: 21:22
Current (09/02/95): 21:27\
References
L. Dubach, C. Ng, NSSDC's Compendium
of Meteorological Space Programs, Satellites, and Experiments, March 1988.
H.J. Kramer, Observation of
the Earth and its Environment - Survey of Missions and Sensors, 2nd Edition,
Springer-Verlag, ISBN: 3-540-578587, May 1994.
Glossary of Terms
- OLS - The Operational Linescan System (OLS) measures visible (0.4-1.1 micrometers) and infrared
(10.25-12.6 micrometers) wavelengths to provide day and night cloud cover imagery. The satellite measures
data at a 0.56 km resolution, which is averaged on board, to produce global coverage at 2.7 km resolution.
All of the 2.7 km resolution (smooth) data is down-linked to the ground sites while a small amount of the
0.56 km resolution (fine) data is stored and down-linked. The OLS is the primary sensor on each DMSP
satellite.
- SSM/I
- Special Sensor Microwave Imager
- SSM/T-1 - Special Sensor Microwave Temperature Sounder. The SSM/T is a seven channel, cross track nadir scanning passive microwave
sounder having a field of view of 14.4 degrees. It measures the Earth surface and atmospheric emission in the 50 to 60 GHz oxygen band.
At nominal altitude, the subtrack spatial
resolution is an circle of 174 km at nadir and an ellipse of 213x304 km toward the limb. There are seven total
cross-track scan positions separated by 12 degrees at frequencies 50.5, 53.2, 54.35, 54.9, 58.4, 58.825 and 59.4 GHZ.
- SSM/T2 - Special Sensor Microwave Water Vapor Profiler
- SSJ/4 - Precipitating Plasma Monitor. The SSJ/4 measures the transfer energy, mass, and momentum through
the magnetosphere-ionosphere in the Earth's magnetic field. The SSJ/4 sensor consists of four electrostatic
analyzers that record the flux of precipitating ions or electrons at 20 fixed energy channels between 50 eV and
30 keV.
- SSIES - Special Sensor Ionospheric Plasma Drift/Scintillation Meter. The SSIES measures the ambient electron
density and temperatures, ambient ion density, the average ion temperature and molecular weight, the plasma drift
and scintillation at the DMSP orbital altitude.
- SSBX-2 - Gamma Ray Particle Detector. The SSB/X-2 is an array-based system which detects the location,
intensity, and spectrum of X-rays emitted from the Earth's atmosphere.
- SSM - Special Sensor Magnetometer. The SSM, a triaxial fluxgate magnetometer, measures geomagnetic fluctuations
associated with geophysical phenomena.
Please see the GHRC Glossary
for terms related to the GHRC and see EOSDIS
Acronyms for a general listing of terms related to the Earth Observing
System Project.
- List of Acronyms
AFB - Air Force Base
AFGWC - Air Force Global Weather Central
DMSP - Defense Meteorological Satellite Program
DoD - Department of Defense
FNMOC - United States Navy Fleet Numerical and Oceanography Center
NESDIS - National Environmental Satellite, Data, and Information Service
NGDC - National Geophysical Data Center
OLS - Operational Linescan System
SSBX-2 - Special Sensor Gamma Ray Particle Detector
SSIES - Special Sensor Ionospheric Plasma Drift/Scintillation Meter
SSJ/4 - Special Sensor Precipitating Plasma Monitor
SSM/I - Special Sensor Microwave Imager
SSM/T-1 - Special Sensor Microwave Temperature Sounder
USAF - United States Air Force
URL - Uniform Resource Locator
Please see the GHRC Glossary for terms related to the GHRC and see EOSDIS Acronyms for a general listing of terms related to the Earth Observing System Project.
Document Information
Document Revision Date:
June 11, 1997
Document Review Date:
September 19, 199
Document ID:
DMSP F-12 Platform Document
Document Curator:
GHRC User Services
support-ghrc@earthdata.nasa.gov
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