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Cos-B

Launch date: 09-Aug-1975 01:48 UT
Mission end: 25-April-1982
Launch vehicle: Thor Delta
Launch mass: 278 kg
Mission phase: Archive
Orbit: The orbit of Cos-B was roughly 100 000 km with a period of 37 hours. This eccentric orbit was chosen to ensure that for most of the time the satellite was outside the Earth's radiation belts.
Achievements: Creation of the 2CG Catalogue that contained about 25 gamma-ray sources out of 30 observations made during the first three years.

Cos-B was ESA's first satellite dedicated to a single experiment. Its scientific mission was to study in detail the sources of extra-terrestrial gamma radiation at energies above about 30 MeV. The originally foreseen duration of the mission was two years, but in fact Cos-B functioned successfully for 6 years and 8 months. During this time an extensive survey of the Galaxy was made in the energy range 50 MeV to 5 GeV.

Mission Objectives

Cos-B's scientific mission was to study in detail the sources of extra-terrestrial gamma radiation at energies above about 30 MeV. The principal objectives were:

  • Study spectrum and distribution of galactic gamma-rays
  • Flux and distribution of extragalactic gamma-ray emission
  • Study known point sources
  • Search for new point sources
     

Spacecraft

Cos-B was configured as a cylinder 1.40 m in diameter and 1.13 m long, with the main experiment package occupying the central region.

Instruments

The Gamma-Ray Telescope

Orbit

The orbit of Cos-B was roughly 100 000 km with a period of 37 hours. This eccentric orbit was chosen to ensure that for most of the time the satellite was outside the Earth's radiation belts. This led to an efficient viewing programme at the price of high cosmic-ray background.

Vital Statistics
 

Overall weight 280 kg
Weight of payload 120 kg
Height of satellite cylinder 1.20 m
Diameter 1.40 m
Number of solar cells 9480
Initial power 109 w
Power after two years 82 w
Average Power 59 w
Battery capacity 6 Ah
Attitude measurement accuracy 1 degree
Transmission frequency 136.95 MHz
Transmission power 6.5 w
Information rate (real time) 80/160/320 kbit/s
Modulation PCM in up-link and down-link
Stability of onboard clock 0.25 msec/3h

 

Last Update: 1 September 2019
16-Dec-2019 12:13 UT

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https://sci.esa.int/s/8dlgDj8

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