ESRO_2B

ESRO 2B

ESRO 2B

Research satellite

ESRO-2B or Iris (International Radiation Investigation Satellite; sometimes Iris 2[4]) or sometimes ESRO II (or ESRO 2), 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.[5]

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Spacecraft

ESRO-2B was an 89 kg (196 lb) cylindrical spacecraft with a length of 85 cm and a diameter of 76 cm. On 10 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. Other experiments could still be operated through ground radio links.

ESRO-2B was launched on a Scout B rocket into a highly elliptical near-polar orbit on 17 May 1968. Its predecessor satellite, ESRO-2A (sometimes Iris 1) failed to reach orbit on 29 May 1967,[6] launching on a Scout B rocket from Vandenberg AFB SLC-5. The cause of failure was malfunction of the third stage of the rocket, preventing the satellite from reaching orbit. ESRO-2A was similar to ESRO-2B except it weighed a little less (74 kg).[4]

Spin-stabilised, ESRO-2B had a spin rate of approximately 40 rpm and re-entered Earth's atmosphere on 8 May 1971 after completing 16,282 orbits.[4]

Instruments

Seven instruments were carried aboard EROS 2B[2] 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.[5] While designed for solar observations ESRO-2B is credited with the detection of X-rays from non-solar sources.[2] The instruments were:

  • Monitor of Energetic Particle Flux
  • Solar and Van Allen Belt Protons
  • Solar and Galactic Alpha Particles and Protons
  • Primary Cosmic Ray Electrons
  • Hard Solar X-rays
  • Soft Solar X-rays
  • Flux and Energy Spectra of Solar and Galactic Cosmic Ray Particles

References

  1. [1]
    "NASA – NSSDCA – Spacecraft – Details".
  2. [2]
    "ESRO 2B". NASA. Retrieved 6 March 2013.
  3. [3]
    "NASA – NSSDCA – Spacecraft – Trajectory Details". nssdc.gsfc.nasa.gov. Retrieved 1 May 2018.
  4. [4]
    "ESRO 2A, 2B (Iris 1, 2)". Gunters Space Page. Retrieved 6 March 2013.
  5. [5]
    "ESRO 2B: May – December 1968". University of Indiana. Retrieved 6 March 2013.
  6. [6]
    "NASA – NSSDCA – Spacecraft – Details".
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