ESRO-2B was an 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, 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).
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.
Instruments Seven instruments were carried aboard EROS 2B 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. While designed for solar observations ESRO-2B is credited with the detection of X-rays from non-solar sources. 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 ==