ESRO 2B
 | |
| Mission type | Astrophysics |
|---|---|
| Operator | ESRO |
| Spacecraft properties | |
| Launch mass | 89 kilograms (196 lb) |
| Start of mission | |
| Launch date | 6 March 1968, 01:55:08 UTC[1] |
| Rocket | Scout B |
| Launch site | Vandenberg SLC-5 |
| End of mission | |
| Decay date | 8 May 1971 |
| Orbital parameters | |
| Reference system | Geocentric |
| Regime | Low Earth |
| Perigee | 326 kilometres (203 mi)[1] |
| Apogee | 1,086 kilometres (675 mi)[1] |
| Inclination | 97.2 degrees[1] |
| Period | 98.9 minutes[1] |
ESRO-2B or Iris (International Radiation Investigation Satellite) was a European astrophysical spin-stabilised research satellite which was launched in 1968. Operated by the European Space Research Organisation, ESRO 2B made astronomical surveys primarily in x-ray and solar particles detectors.[2]
Spacecraft
ESRO-2B was an 89 kg (196 lb) cylindrical spacecraft with a length of 85 cm and a diameter of 76 cm. In December 1968 (approx 195 days since mission start) the on-board tape recorder suffered a mechanical failure. This effectively ended the two X-ray experiments as they did not provide any significant data return from then on.
ESRO-2B was launched on a Scout B rocket into a highly elliptical near-polar orbit on 16 May 1968 after the ESRO-2A failed to reach orbit.[3]
Spin-stabilised, ESRO-2B had a spin rate of approximately 40 rpm and re-entered the Earths atmosphere on 8 May 1971 after completing 16,282 orbits.[3]
Instruments
Seven instruments were carried aboard EROS 2B[1] designed to detect high energy cosmic rays, determine the total flux of solar X-rays and to measure Van Allen belt protons and cosmic ray protons.[2] While designed for solar observations ESRO-2B is credited with the detection of X-rays from non-solar sources.[1]