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Platform Description

Defense Meteorological Satellite Program (DMSP) Satellite F13


Summary

The Defense Meteorological Satellite Program (DMSP) provides global visible and infrared cloud data and other specialized meteorological, oceanographic and solar-geophysical data in support of worldwide Department of Defense (DoD) operations. The DMSP F13 satellite, launched in March 1995, is in a near circular, sun synchronous, polar orbit. This document describes the DMSP mission, the satellite, and its environment. The document also briefly describes the ground data system. Separate platform description documents are available for the F8, F10, F11, F15, and F17 satellites.

Table of Contents

1. Platform or Data Collection Environment Overview
2. Ground Segment Information
3. References
4. Glossary of Terms
5. Acronyms and Abbreviations
6. Document Information

1.Platform or Data Collection Environment Overview

Platform or Data Collection Environment Long Name, Platform Acronym

Defense Meteorological Satellite Program (DMSP) Block 5D-2 Satellite F13, DMSP F13

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 were declassified and made available to the civil and scientific communities. 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 worldwide Department of Defense (DoD) operations.

Platform Parameters

DMSP Satellite F13 was built by General Electric's Astro-Space Division (now part of Martin Marietta Astro Space). It was launched on March 24, 1995 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 F13 is in a near circular, sun synchronous, polar orbit.

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 uplinked to the spacecraft daily. Three-axis attitude control is maintained in the orbital configuration by automatic momentum exchange between three momentum wheels. Onboard 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 are transmitted in real time to tactical terminals worldwide. Data are also stored using onboard 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:

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

2.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 are transmitted in real time to tactical terminals worldwide. Data are also stored using onboard 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):

3.References

Dubach L., and C. Ng. 1988. NSSDC's Compendium of Meteorological Space Programs, Satellites, and Experiments, March 1988.

Kramer, H. J. 1994. Observation of the Earth and its Environment - Survey of Missions and Sensors, 2nd Edition, Springer-Verlag, ISBN: 3-540-578587, May 1994.

4.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 downlinked to the ground sites while a small amount of the 0.56 km resolution (fine) data is stored and downlinked. 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/T-2 - 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 Ionspheric 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 that 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.

SSZ: The SSZ is a static Earth viewing sensor, monitoring electromagnetic radiation.

5. Acronyms and Abbreviations

The following acronyms and abbreviations are used in this document.

AFB Air Force Base
AFGWC Air Force Global Weather Central
DMSP Defense Meteorological Satellite Program
DoD Department of Defense
DSAP Defense System Applications Program
DAPP Defense Acquisition and Processing Program
eV Electron Volts
FNMOC United States Navy Fleet Numerical and Oceanography Center
kbps Kilobits Per Second
keV Kilo Electron Volts
Mbps Megabits Per Second
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 Special Sensor Magnetometer
SSM/I Special Sensor Microwave Imager
SSM/T-1 Special Sensor Microwave Temperature Sounder
SSM/T-2 Special Sensor Microwave Water Vapor Profiler
USAF United States Air Force
URL Uniform Resource Locator

6.Document Information

Revision Date: MSFC: September 19, 1995; NSIDC: November 12, 1996
Review Date: MSFC: September 19, 1995; NSIDC: November 12, 1996
Document ID: DMSP F-10 Platform Document
Document Curators: NSIDC Writers
Document URL: http://nsidc.org/data/docs/daac/f13_platform.gd.html