Galactic Radiation and Background

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Model of the first GRAB satellite

Galactic Radiation and Background ( GRAB ) refers to the first series of US - spy satellites for electronic reconnaissance . They were launched in the early 1960s and were supposed to clear up the radar systems of the Soviet Union , whereby they also carried a scientific payload for camouflage, which is why the satellites were officially named Galactic Energy Balance Experiment (Greb-E) and later SolRad (for Solar Radiation) .


The 19 kg heavy GRAB satellites, which were developed from 1958 to 1960 by the Naval Research Laboratory (including the engineer Reid D. Mayo) under the code name Tattletale , are generally designed as spheres with a diameter of 51 cm. The energy supply is ensured by several solar cells , whereby these were placed in such a way that roughly the same amount of electricity is generated in each spatial position. This is necessary because the satellite is spin stabilized and cannot permanently align with one side to the sun. The exact specifications of the ELINT payload are unknown, however, due to the existing Soviet radars, it must have operated at least in a frequency range around 3  GHz . Catched signals were forwarded directly to a ground station without intermediate storage in order to save them there on magnetic tapes . This was then brought by plane to the Naval Research Laboratory, where it was then evaluated for the first time. The tapes were then taken to the National Security Agency or Strategic Air Command for further analysis , where they were used to improve reconnaissance and to draw up military plans.

The measuring devices, which were primarily used for camouflage, to examine X-rays and to record the Lyman series, were fully operational and were used for solar research . The downlink of these instruments was 108 or 136 MHz , depending on the satellite  .

The GRAB satellites were launched together with another satellite, mostly on a Thor Able-Star launcher. The target orbit had an inclination of 66.7 °, a perigee of 614 km and an apogee of 1061 km. At the end of the program, Poppy series satellites were used for ELINT reconnaissance.

List of satellites

A GRAB receiving station
Surname begin designation Launcher Launch site status
GRAVE 1 / SOLRAD-1 June 22, 1960 1960-007B Thor Able star CCAFS LC-17B In orbit, was operational for three months
GRAVE 2 / SOLRAD-2 November 30, 1960 - Thor Able star CCAFS LC-17B False start
GRAVE 3 / SOLRAD-3 June 29, 1961 1961-015B Thor Able star CCAFS LC-17B In orbit, broadcast from July 15, 1961 and served for 14 months
GRAVE 4A / SOLRAD-4A January 24, 1962 - Thor Able star CCAFS LC-17B False start
GRAVE 4B / SOLRAD-4B April 26, 1962 - Scout X-2 VAFB SLC-5 False start

Web links

Commons : Program GRAB  - collection of images, videos and audio files

Individual evidence

  1. SOLRAD 1 in the NSSDCA Master Catalog (English)
  2. SOLRAD 2 in the NSSDCA Master Catalog (English)
  3. Injun 1 in the NSSDCA Master Catalog (English)
  4. SR 4 / GREB 4 in the NSSDCA Master Catalog (English)
  5. SOLRAD 4B in the NSSDCA Master Catalog (English)