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|Deep Space 1 - |
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The Deep Space 1 (DS1) was the first of a series of technology demonstration probes being developed by NASA's New Millennium Program. The spacecraft was to fly by asteroid 1992 KD and possibly comets Wilson-Harrington and Borrelly. Along with the technology demonstrations, the probe carried the Miniature Integrated Camera-Spectrometer (MICAS), an instrument combining two visible imaging channels with UV and IR spectrometers. MICAS was used to study the chemical composition, geomorphology, size, spin-state, and atmosphere of the target objects. It also carried the Plasma Experiment for Planetary Exploration (PEPE), an ion and electron spectrometer which will measure the solar wind during cruise, the interaction of the solar wind with target bodies during encounters, and the composition of the cometary coma.
Spacecraft and Subsystems
The Deep Space 1 spacecraft was built on an octagonal aluminum frame, 2.5 m high, 2.1 m deep, and 1.7 m wide. The launch mass of the spacecraft was about 486.3 kg, which included 31.1 kg of hydrazine and 81.5 kg of xenon gas. The probe was powered by batteries and two solar panel "wings" attached to the sides of the frame which span roughly 11.75 m when deployed. The solar panels, designated SCARLET II (Solar Concentrator Arrays with Refractive Linear Element Technology) constituted one of the technology tests on the spacecraft. A cylindrical lens concentrated sunlight on a strip of GaInP2/GaAs/Ge photovoltaic cells and acted to protect the cells. Each solar array consisted of 4 160 cm x 113 cm panels. The array furnished 2300 W at 100 volts at the beginning of the mission, and less as the spacecraft moved further from the Sun and the solar cells aged. Communications were via a high gain antenna, two low gain antennae, and a Ka band antenna, all mounted on top of the spacecraft.
Propulsion was provided by a xenon ion engine mounted in the propulsion unit on the bottom of the frame. The 30 cm diameter engine consisted of an ionization chamber into which xenon gas was injected. Electrons were emitted by a cathode traverse discharge tube and collided with the xenon gas, stripping off electrons and creating positive ions. The ions were accelerated through a 1280 volt grid at to 31.5 km/sec and ejected from the spacecraft as an ion beam, producing 0.09 Newtons (0.02 pounds) of thrust at maximum power (2300 W) and 0.02 N at the minimum operational power of 500 W. The excess electrons were collected and injected into the ion beam to neutralize the electric charge. Of the 81.5 kg of xenon, approximately 75 kg was expected to be used during the primary mission. Other technologies tested on this mission included a solar concentrator array, autonomous navigation plus two other autonomy experiments, small transponder, Ka-band solid state power amplifier, and experiments in low power electronics, power switching, and multifunctional structures (in which electronics, cabling, and thermal control were integrated into a load bearing element).
|Deep Space 1 - Deep Space 1 in flight|
Credit: NASA. 9,975 bytes. 300 x 238 pixels.
Deep Space 1 was sucessfully launched from pad 17-A at the Cape Canaveral Air Station at 12:08 UT (8:08 a.m. EDT), the first launch under NASA's Med-Lite booster program, on a Delta 7326-9.5 with three strap-on solid propellant rockets. At 13:01 UT the third stage burn put DS1 into its solar orbit trajectory. DS1 separated from the Delta II about 550 km above the Indian Ocean. Telemetry was recieved by the NASA Deep Space Network 1 hour, 37 minutes after launch, a 13 minute delay from the expected time. The reason for the delay was not known. All critical spacecraft systems were performing well. DS1 was to fly by the near-Earth asteroid 1992 KD on 28 July 1999 at a distance of 5 to 10 km. The diameter of 1992 KD is about 3 km and its orbit crosses that of Mars. The primary mission was planned to last until 18 September 1999, with the possibility of an extended mission to fly by the dormant comet Wilson-Harrington in January 2001 and comet Borrelly in September 2001. DS1 was originally scheduled to fly by the asteroid 3352 McAuliffe in 1999 and comet P/West-Kohoutek-Ikemura and the planet Mars in the year 2000 but because of a launch delay these targets were no longer possible.
Total Mass: 475 kg.
The primary mission of Deep Space 1 probe was to test new technology for future interplanetary spacecraft, the main experiment being an ion propulsion engine using xenon propellant. It had an initial mass of 486.3 kg, including 81.5 kg of Xenon and 31.1 kg of hydrazine propellants. Deep Space 1 successfully started its ion engine on November 24 after an initial attempt failed after four minutes on November 10. From its initial solar orbit of 0.99 AU x 1.32 AU x 0.4 degree, Deep Space 1 was to fly past the 3 km diameter asteroid 1992 KD at its perihelion of 1.33 AU. An additional 2001 flyby of Comet 19P/Borrelly was also planned, by which time Deep Space 1 was to have manoeuvred to an orbit of 1.12 x 1.42 AU. Additional Details: Deep Space 1.