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Astrid is a microsatellite designed to investigate the near-Earth plasma environment with emphasis on neutral particle phenomena. By making novel measurements of uncharged particles, it is possible to increase the knowledge of charged particles in the Earth's radiation belts and ring current. The energetic ions in the ring current charge-exchange with cold hydrogen atoms in the Earths' exosphere. The resulting energetic neutral atoms (ENA) escape from the ring current. ENA can thus be used to remotely "image" the ring current in order to study the morphology and dynamics of this region. Another important field of study is the outflow of neutrals from the auroral region. ASTRID is also the first technological demonstration of the FREJA-C microsatellite platform developed by the Swedish Space Corporation. The spacecraft is spin stabilized, with the spin axis pointing towards the sun. Its orbit is circular at 1,000 km, with inclination of 83 degrees.

The payload, designed by The Swedish Institute of Space Physics, Kiruna, consists of three experiments: a Neutral Particle Imager (PIPPI); an electron spectrometer (EMIL); and a miniature UV imaging system (MIO). Initially the spacecraft name Astrid was selected just as a good old-fashioned Swedish female name, but within a short time it was decided to name the instruments after characters in the books of the very popular Swedish writer of children's books, Astrid Lindgren.

The spacecraft has 8 MB of on-board storage, and a data compression card used for reduction and lossless compression of data. Data are transmitted at 8 kbps to a ground station operating at 400 MHz at the Swedish Institute of Space Physics in Kiruna, which also provides an uplink capability. One pass per day is covered by the Esrange ground station at 128 kbps using S-band. Esrange is also responsible for the platform operations. Science data rates are 111 Kbps and 7.5 Kbps.

Design lifetime was one year, but as of March 1, 1995 the scientific instruments became inoperable. Further information on the spacecraft and experiments, and sample data, can be found on the WWW pages at

Alternate Names

  • 23464

Facts in Brief

Launch Date: 1995-01-24
Launch Vehicle: Cosmos
Launch Site: Plesetsk, Russia
Mass: 24.7 kg
Nominal Power: 38.5 W

Funding Agencies

  • Unknown (Sweden)
  • Unknown (Finland)
  • Unknown (Federal Republic of Germany)
  • Unknown (United States)
  • Unknown (Canada)


  • Space Physics

Additional Information

Questions and comments about this spacecraft can be directed to: Dr. H. Kent Hills



NameRoleOriginal AffiliationE-mail
Mr. Olle NorbergProject ScientistSwedish Institute for Space
Ms. Anna LaurinProject ManagerSwedish Space
Mr. Stig-Ove SilverlindMission Operations ManagerSwedish Space
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