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Rebuilt Titan 2 Launches Weather Satellite

Titan 2 launches DMSP F15
Titan 2 launches DMSP F15
What was unusual about the launch of a weather satellite into polar orbit in December 1999?

The satellite, known as Defense Meteorological Satellite Program DMSP F15, was boosted into space aboard a U.S. Air Force Titan 2 rocket from Space Launch Complex-4 West at Vandenberg Air Force Base in California. Six minutes after blast off, an apogee kick motor attached to the satellite fired to place the craft in the proper orbit above Earth.

The gem in this story was the Titan 2 rocket, which once was an intercontinental ballistic missile (ICBM) stationed at McConnell Air Force Base in Kansas.

During the Cold War, America's fleet of Titan 2 ICBMs stood ready to rain nuclear destruction on the former Soviet Union. When the aging Titan 2 ICBM national defense system was replaced and deactivated by June 1987, the U.S. government decided to convert fourteen of the leftover missiles to launch U.S. government payloads to Earth orbit. The vintage Titan 2s decommissioned by the Air Force were remodeled in the 1990s by Lockheed Martin Astronautics to carry payloads into space.

Titan Rockets

The Titan family dates to October 1955, when the Air Force awarded Lockheed Martin (formerly the Martin Company) a contract to build an intercontinental ballistic missile (ICBM). Known as the Titan 1, it was the nation's first two-stage ICBM and first underground silo-based ICBM.

Later, more than 140 Titan 2 ICBMs were built as the vanguard of America's strategic deterrent force.

Deactivation of the Titan 2 ICBM system began in July 1982 and was completed in June 1987. The deactivated missiles are now in storage at Davis-Monthan AFB, Arizona.

The Air Force successfully launched the first Titan 2 space launch vehicle from Vandenberg AFB September 5, 1988.

All DMSP satellites are launched on Titan 2 boosters from Vandenberg. The most recent previous launch was April 4, 1997. That flight was the first DMSP launch on a Titan 2 booster. NOAA's own civilian weather satellites also are launched on Titan 2 rockets.

The December 1999 blast-off was the ninth for a converted Titan 2 and the second DMSP weather satellite launched by a Titan 2. All nine launched have been successful.

Earlier Space Flights

Titan 2s also flew in NASA's Gemini manned space program in the mid-1960s. NASA's Clementine spacecraft, which was launched aboard a Titan 2 in January 1994, discovered water on the moon in November 1996.

Titan 2 is a two-stage liquid-fuel booster able to lift approximately 4,200 lbs. into a polar low-Earth circular orbit.

From ICBM to Space Booster

Changing a Titan 2 ICBM into a space rocket required:
    Modifying the end of the second stage to hold a satellite,

    Manufacturing a 10-ft. diameter payload fairing, or cover, of variable lengths plus payload adapters,

    Refurbishing the Titan's liquid-fuel rocket engines,

    Upgrading the inertial guidance system,

    Developing command, destruct and telemetry systems,

    Modifying Vandenberg's Space Launch Complex-4 West for the launches, and

    Putting the payload on the rocket.
The DMSP Satellite

The DMSP system depends on two satellites operated in space by the National Oceanic and Atmospheric Administration (NOAA). Weather data sent down to Earth by DMSP satellites is used by the U.S. military for strategic and tactical forecasting over land, sea and air operations around the globe. In addition, the satellites are used by other parts of the government and by universities for detecting forest fires, monitoring volcanic activity, hurricane forecasting and helping long-term climate-change studies.

Artist concept of DMSP F15 satellite in orbit over Earth
Artist concept of DMSP F15 satellite
NOAA controls and operates the DMSP satellites in a cooperative program with the U.S. Air Force.

DMSP satellites circle the Earth at an altitude of about 500 miles in a near-polar, sun-synchronous orbit. Each scans an area 1,800 miles wide and covers the entire Earth in about 12 hours.

The main sensor on board a DMSP satellite is known as the Operational Linescan System. It observes clouds in both visible and infrared light.

A second important sensor is the so-called Special Sensor Microwave Imager. It provides all-weather capability for worldwide tactical operations and is particularly useful in typing and forecasting severe storm activity.

The spacecraft also carries a group of additional sensors that collect a broad range of meteorological and space environmental data.

Replacing Old Satellites

DMSP F15 replaces two older DMSPs with worn out systems. Five more DMSP satellites await launch in coming years.

At the time of the launch of DMSP F15, the U.S. Air Force had four DMSP satellites in operation. DMSP F15 replaced two of them. The two older satellites replaced, F12 and F14, each had tape recorder failures, although some other equipment aboard the satellites still was functioning.

DMSP F15 has more capability than the two replaced satellites combined. F12 and F14 use older reel-to-reel tape recorders. F15 has two solid-state recorders, which work something like RAM memory in a personal computer. The solid-state recorders are expected to have a longer operational life.

Weather Forecasting

Data from DSMP satellites helps identify, locate and determine the intensity of severe weather such as thunderstorms, hurricanes and typhoons. It also is used to form three-dimensional cloud analyses, which are the basis for computer forecast models. Additionally, space environmental data is used to assist in high frequency communications, over-the-horizon radar, and spacecraft drag and reentry tasks.

Ground Stations

Each DMSP satellite stores images of a geographic area as data on a recorder and then replays the data when over one of four ground stations located near Fairbanks, Alaska; New Boston, New Hampshire; Thule Air Base, Greenland; and Kaena Point, Hawaii.

From the four command stations on the ground, weather data is relayed to the Air Force Weather Agency at Offutt Air Force Base, Nebraska, to the U.S. Navy's Fleet Numerical Meteorological and Oceanographic Center at Monterey, California, and to the Air Force's 55th Space Weather Squadron at Falcon Air Force Base, Colorado. At those stations, the information is used to compile numerous worldwide weather and space environmental reports and forecasts.

Artist concept of DMSP F15 satellite in orbit over Earth
The satellite also can transmit meteorological data in real-time directly to Air Force, Army, Navy and Marine Corps tactical ground stations around the world and to Navy ships worldwide.

On a Different Path

The December 1999 launch was unique for the DMSP system because the satellite was placed in an orbit different from usual. Its path through space 500 miles above Earth is designed to improve weather forecasting over global hotspots in which the U.S. military has an interest. For instance, the satellite passes above the Korean Peninsula and Kosovo at a time different from other satellites in space. That offers better nighttime weather monitoring in those areas.

DMSP F15 is first in a new generation of weather satellites built by Lockheed Martin Missiles & Space. They have a new spacecraft structure, two additional panels on the solar array for more power, an additional battery, larger computer memory, improved computer software and two solid-state recorders replacing older reel-to-reel tape recorders used in previous DMSPs.

Radar Calibration

DMSP F15 also carries an experimental payload called Radar Calibration (RADCAL) to collect and transmit C-band data to test C-band tracking radar performance at the 30th Space Wing at Vandenberg Air Force Base. It also transmits Doppler data for the Naval Research Laboratory's Coherent Electromagnetic Tomography (CERTO) experiment.

The Defense Meteorological Satellite Program is managed at the Space and Missile Systems Center, Los Angeles Air Force Base, California Satellite command and control is provided by a joint-operational team at the U.S. Department of Commerce's National Oceanic and Atmospheric Administration, Suitland, Maryland. DMSP data also furnished to the civilian community through NOAA.

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