Delta 183 Delta Star

Early on, the SDI program instituted a major technology demonstration program that placed priority on dramatically reducing the size and weight of critical propulsion, sensor, data processing, and other electronic subsystems to enable an effective hit-to-kill interceptor system. Among the most notable experiment in this highly successful series was Delta 183 (or Delta Star) in 1989, which, over a nine month period, gathered very important signature information that is most pertinent to efforts to accomplish intercept in boost-phase and midcourse in the face of responsive countermeasures.

The third SDI mission was DELTA 183. It involved the DELTA STAR spacecraft, which contained a suite of sensors, a command and data handling system, seven scientific instruments and a Laser Illumination Detection System (LIDS). Like the DELTA 181 mission's data, DELTA 183 data was transmitted via telemetry downlink to stations on the ground. The primary objectives of the mission were to: 1) observe the DELTA's second stage rocket "burns" in various background environments and 2) record and transmit data about those background environments in general.

The Delta 183 program was proposed in 1988 by the Strategic Defense Initiative Organization (SDIO), originally as a joint effort between the United States and the Soviet Union involving the Russian Mir space station. When the Soviets decided not to participate, SDIO proceeded unilaterally to conduct the mission without direct involvement of Mir. The primary motivation for the experiment was to engage the USSR in joint activities to allay their concerns about the threat posed by the SDIO missile-defense activities being pursued at the time. A secondary objective was to demonstrate that space experiments could be conceived and executed rapidly and cost-effectively. Indeed, from its conception to launch, the Delta 183 program cost approximately $200 million and took just 14 months, three spent waiting for access to the launch facility.

The program's name, Delta 183, was derived from the designation of the launch vehicle; the spacecraft itself was called Delta Star. It consisted of two sections: the McDonnell Douglas orbital operations control assembly mated to the sensor module. The instruments were boresighted together parallel to the axis of the module; pointing was provided by the spacecraft's attitude-control system. The sensor ensemble included

• an infrared imager, operating much like a video camera in any of three spectral bands in the short- to mid-wave region
• a long-wave infrared imager adapted from the guidance and control section of a Maverick missile
• an ensemble of three imagers and four photometers, which produced imagery and intensity data in several visible and ultraviolet bands
• an ultraviolet-intensified CCD (charge- coupled device) video camera
• a laser detection and ranging device

The DELTA 183 launch was attempted for the first time on 15 March 1989, but the countdown was scrubbed due to launch vehicle and spacecraft problems. The second countdown was attempted on 24 March 1989, and it went well. The DELTA Model 3920 booster lifted off Pad 17B at 2150:49Z on the 24th, and the vehicle rolled into a flight azimuth of 60 degrees. During the first phase of the mission, the DELTA's second stage placed the DELTA STAR into a low-Earth orbit inclined 47.7 degrees to the equator. After coasting for approximately one-half revolution, the second stage fired again to circularize its orbit at an altitude of 269 nautical miles.

The DELTA STAR spacecraft then separated from the second stage, and the second stage performed an evasive maneuver. The DELTA STAR observed the second stage's de-orbit burn and reentry into the atmosphere. During the second phase of the mission, the DELTA STAR made observations and transmitted data to ground stations over the next several months.