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Platform Description

Defense Meteorological Satellite Program (DMSP) Satellite F15


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), Department of Commerce (DoC), and National Aeronautics and Space Administration (NASA) operations. The DMSP F15 satellite, launched in December 1999, is in a near-circular, sun-synchronous, polar orbit. This document provides an overview of the DMSP mission, the F15 satellite, and a brief overview of the ground data system. Separate platform description documents are available for the F8, F10, F11, F13, 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 Overview

Platform Long Name, Acronym

Defense Meteorological Satellite Program (DMSP) Block 5D-3 Satellite F15, DMSP F15

Platform Introduction

DMSP, originally known as the Defense System Applications Program (DSAP) and the Defense Acquisition and Processing Program (DAPP), is a long-term satellite program designed to monitor the meteorological, oceanographic and solar-geophysical environment of the Earth in support of DoD operations. The United States Air Force (USAF) has maintained an operational constellation of two near-polar, sun-synchronous satellites for military purposes since the first launches of Block 1 DMSP satellites in 1962. In December 1972, DMSP data were declassified and made available to the civil and scientific communities.

All spacecraft launched have had a tactical (direct readout) and a strategic (stored data) capacity. DMSP-5D3 is the most recent version of the military meteorological satellites of the Defense Meteorological Satellite Program and F15 is the first satellite of the DMSP-5D3 series. However, DMSP F15 is technically considered a hybrid platform as it is outfitted with the new DMSP-5D3 spacecraft bus and the DMSP-5D2 suite of sensors.

Collection Environment

Satellite

Platform Program Management

Under a 1994 Presidential directive, a tri-agency organization between the DoD, DoC, and NASA was formed in order to converge the parallel polar-orbiting weather satellite programs of the DoD and DoC--the DMSP and Polar Orbiting Environmental Satellite (POES) programs, respectively. The goal of the tri-agency effort is the development of a National Polar Orbiting Environmental Satellite System (NPOESS) that will ultimately meet the needs of all three agencies. Funding for DMSP continues to be provided by the DoD and USAF.

As part of the NPOESS convergence effort, the DoC assumed control of DMSP satellites from the USAF in 1998. Satellite command is provided by a joint-operational team at the U.S. Department of Commerce's National Oceanic and Atmospheric Administration (NOAA) control center in Suitland, Maryland. DMSP data are also distributed through NOAA to the civilian and scientific communities. The USAF Space Systems Division at Los Angeles Air Force Base in Los Angeles, California continues to be responsible for the development and acquisition of DMSP systems.

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 DoD, DoC, and NASA operations.

Platform Parameters

The DMSP F15 satellite was built by General Electric's Astro-Space Division (now part of Northrop Grumman/Lockheed Martin). It was launched on 12 December 1999 from Vandenberg AFB, California using a Titan II rocket. The spacecraft is 4.29 meters in length with an on-orbit mass of 1154.4 kilograms.

The DMSP F15 satellite is the first of a new suite of weather satellites built by Lockheed Martin Missiles & Space and has more capability than two of its predecessors, F12 and F14, combined. Improvements include a new spacecraft structure, two additional panels on the solar array for more power, an additional battery, more computer memory, improved computer software, and two solid-state recorders replacing older reel-to-reel tape recorders used in previous DMSPs.

Coverage Information

The DMSP F15 satellite is in a near-circular, sun-synchronous, polar orbit. Additional details of the platform are as follows:

Attitude Characteristics

Pointing accuracy: 0.01 degree (primary), 0.12 degree (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. Operation 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.

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

The following Block 5D-2 sensors are on board the DMSP F15 platform:

Also carried on board DMSP F15 is an experimental payload, called the Radar Calibration (RADCAL) beacon, that is used to transmit C-band data for the purpose of testing C-band tracking radar performance at Vandenberg Air Force Base. RADCAL also transmits Doppler data for the Naval Research Laboratory's Coherent Electromagnetic Tomography (CERTO) experiment.

The RADCAL beacon operates at 150 MHz and 400 MHz. On-orbit testing conducted in August 2005 confirmed that transmissions from the RADCAL 150 Mhz beacon produced interference in the SSM/I 22 GHz vertical polarization (22V) channel and that the 400 Mhz beacon interfered with SSMT-2 channel 4 performance. The SSMT-2 on F15 has since been declared non-operational due to an unrelated component failure. Thus, users of F15 SSM/I data should be advised that the 22V channel will be dramatically degraded during RADCAL beacon transmission, particularly with regards to snow classification and depth.

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) at Offutt AFB, Nebraska and by the Fleet Numerical Meteorology and Oceanography Center (FNMOC) in 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. 2002. Observation of the Earth and Its Environment: Survey of Missions and Sensors, 4th Edition, Springer-Verlag, ISBN: 3540423885, May 2002.

Strom, S. R. and G. Iwanaga. 2005. "Overview and History of the Defense Meteorological Satellite Program," Crosslink, The Aerospace Corporation magazine of advances in aerospace technology, Vol. 6, No 1, 2005.

Sweetman, B. 2006. Jane's Space Directory 2006/2007, Jane's Information Group, ISBN: 071062767X, June 2006.

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.

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.

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.

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.

SSM: Special Sensor Magnetometer. The SSM, a triaxial fluxgate magnetometer, measures geomagnetic fluctuations associated with geophysical phenomena.

SSM/I: Special Sensor Microwave Imager. The SSM/I is a seven-channel, four-frequency, orthogonally polarized, passive microwave radiometric system that measures atmospheric, ocean and terrain microwave brightness temperatures at 19.35, 22.2, 37.0, and 85.5 GHz.

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's surface and atmospheric emission in the 50 to 60 GHz oxygen band. At nominal altitude, the subtrack spatial resolution is a 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. The SSM/T-2 water profiler sensor is a five channel, total power microwave radiometer designed to provide global monitoring of water vapor concentration in the atmosphere under all conditions. With two window channels and three channels in the 183.31 GHz water vapor resonance line, SSM/T-2 is able to capitalize on the reduced sensitivity of the microwave region to cloud attenuation.

 

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
DoC Department of Commerce
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 Kiloelectron Volts
Mbps Megabits Per Second
NESDIS National Environmental Satellite Data and Information Service
NGDC National Geophysical Data Center
NOAA National Oceanic and Atmospheric Administration
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

Document Creation Date: November 2008
Document ID: DMSP F-15 Platform Document
Document Curators: NSIDC Writers
Document URL: http://nsidc.org/data/docs/daac/f15_platform.gd.html