Instrument Host Overview
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  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