PDS_VERSION_ID = PDS3 RECORD_TYPE = STREAM LABEL_REVISION_NOTE = "CREATION: TONY L. FARNHAM, 26 SEP 2003" OBJECT = INSTRUMENT_HOST INSTRUMENT_HOST_ID = "DS1" OBJECT = INSTRUMENT_HOST_INFORMATION INSTRUMENT_HOST_NAME = "DEEP SPACE 1" INSTRUMENT_HOST_TYPE = "SPACECRAFT" INSTRUMENT_HOST_DESC = " Instrument Host Overview ======================== Deep Space 1 (DS1) was the first mission representing the NASA New Millennium program, which was chartered to validate in space advanced, high-risk technologies important for future space and Earth science programs. The advanced technology payload tested on DS1 comprised solar electric propulsion, solar concentrator arrays, autonomous on-board navigation and other autonomous systems, several telecommunications and microelectronics devices, and two low-mass integrated science instrument packages. The technology evaluations occurred during the primary mission phase and, with successful completion of these tasks, an extended mission devoted to scientific studies was approved. Spacecraft and Subsystems The Deep Space 1 spacecraft was built on an octagonal aluminum frame bus 1.1 x 1.1 x 1.5 m in size. With instruments and systems attached, the spacecraft measured 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. Thermal control was accomplished with the standard multilayer insulation or thermal blanketing, as well as with electrical heaters and radiators. Attitude orientation sensing was achieved through the use of a star sensor, an inertial measurement unit (gyroscope) and a Sun sensor. Hydrazine thrusters were used for maintaining attitude control, with the spacecraft in three-axis stabilized mode. The probe was powered by a battery and two solar panel 'wings'. The battery was a 24 amp-hour nickel hydrogen battery, which provided power immediately after launch. It also supplemented the solar array power during ion engine thrusting, to cover transients in the spacecraft's power consumption, and during periods when the solar arrays were pointed too far away from the sun to collect sufficient energy to run all of the spacecraft systems. 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 four 160 cm x 113 cm panels. The array furnished 2500 W at 100 volts at the beginning of the mission, but this level dropped as the spacecraft moved further from the Sun and as 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. A third low gain antenna was mounted on the bottom of the spacecraft. The Small Deep Space Transponder and the Ka-band Solid-State Power amplifier were two of the advanced technologies, allowing data to be sent over smaller antennas with less power than missions using the X-band. The propulsion system represented one of the advanced new technologies being validated. Thrust 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 is 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 17 kg were consumed during the primary mission. Only low-levels of thrust are available from the ion engine, so separate hydrazine thrusters were used for attitude control and for situations where a rapid acceleration was required (e.g. last minute course corrections during an encounter). Because of the long-term thrusting of the ion engine, DS1 needed to take a different approach to navigation and decision-making, and in this vein, three of the advanced technologies dealt with spacecraft autonomy. DS1 was able to find its location in the solar system by taking images of known asteroids and comparing their positions against the background stars. Furthermore, it had advanced on-board decision-making capabilities and improved communications regarding spacecraft health. DS1 carried two different scientific instrument packages. First, the Miniature Integrated Camera Spectrometer (MICAS) included a camera and an infrared imaging spectrometer. MICAS also had an ultraviolet spectrometer, but this part of the instrument did not function properly. Second, the Plasma Experiment for Planetary Exploration (PEPE) contained several instruments for studying space plasmas. Not only was PEPE used to obtain scientific measurements of space plasmas during cruise phase and during the asteroid and comet encounters, but it was also used to determine the effects of the ion engine on the spacecraft, the instruments and the surrounding environment. Although there were 12 advanced technologies on Deep Space 1, the rest of the spacecraft was composed of current, low-cost components that have been tried and tested on other missions. (The Deep Space 1 flight computer, for instance, was based on that used by Mars Pathfinder and other missions.) This approach was used because the focus of the New Millennium Program is on proving that certain advanced technologies work in space, not on building complete spacecraft representative of those to be used in future missions. Because of the high-risk, low cost aspect of the mission, there were no back-up systems to provide redundancy against the failure of major components. The 12 advanced technologies subjected to verification on DS1: Major spacecraft sub-systems 1) Solar electric propulsion system 2) Solar concentrator arrays Spacecraft autonomy: 3) Autonomous onboard optical navigation 4) Beacon monitor operations 5) Autonomous remote agent Science instruments 6) Miniature integrated camera and spectrometer (MICAS) 7) Plasma experiment for planetary exploration (PEPE) Telecommunications 8) Small deep-space transponder 9) Ka-band solid-state power amplifier Microelectronics 10) Low-power electronics 11) Power activation and switching modules 12) Multifunctional structure" END_OBJECT = INSTRUMENT_HOST_INFORMATION OBJECT = INSTRUMENT_HOST_REFERENCE_INFO REFERENCE_KEY_ID = "N/A" END_OBJECT = INSTRUMENT_HOST_REFERENCE_INFO END_OBJECT = INSTRUMENT_HOST END