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CHRISTA-SPAS 2 (Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere-Shuttle Pallet Satellite 2) was a German-American free-flying module that was released from the Shuttle Remote Manipulator System (RMS) on STS 85 to monitor atmospheric constituents (ozone, etc.) of the middle atmosphere by means of infrared spectrometers. It was retrieved by the Shuttle RMS after nine days of free flying in the vicinity of the Shuttle. During its free flight about 66 minirockets and balloons were launched by the United States and Germany to concurrently monitor the same regions of the atmosphere as the spacecraft did. Initial orbital parameters of the spacecraft were close to those of the Shuttle.

The primary experiment was the CRISTA, a system of three telescopes and four spectrometers to measure infrared radiation emitted by the Earth's middle atmosphere. A complementary instrument called MAHRSI (Middle Atmosphere High Resolution Spectrograph Investigation) was also carried on the payload together with a passive experiment called SESAM (Surface Effects Sample Monitor). MAHRSI measured ultraviolet radiation emitted and scattered by the Earth's atmosphere.

Two additional experiments were mounted on the SPAS and were activated during free-flight. The Mini Dual Earth Sensor (MiDES) was used to gather operational data of the Earth horizon positions, and the Interferometry Program Experiment-II (IPEX-II) to measure the vibration of the SPAS structure.

Alternate Names

  • 24890
  • Cryogenic IR Spectrometers and Telescopes for the Atmosphere
  • Shuttle Palette Satellite 2

Facts in Brief

Launch Date: 1997-08-07
Launch Vehicle: Shuttle
Launch Site: Cape Canaveral, United States

Funding Agencies

  • German Space Agency (Federal Republic of Germany)
  • NASA Office of Mission to Planet Earth (United States)


  • Earth Science

Additional Information

Questions and comments about this spacecraft can be directed to: Coordinated Request and User Support Office


Related Information/Data at NSSDC

STS 85 (CRISTA-SPAS 2 deployment mission)

Other sources of CRISTA-SPAS 2 data/information

CRISTA home page (U. of Wuppertal)
MAHRSI home page (NRL)

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