ISEE 1 [NASA]
The Explorer-class mother spacecraft, ISEE 1 (International Sun-Earth Explorer 1), was part of the mother / daughter / heliocentric mission (ISEE 1, ISEE 2, ISEE 3). The purposes of the mission were:
The three spacecraft carried a number of complementary instruments for making measurements of plasmas, energetic particles, waves, and fields. The mission thus extended the investigations of previous IMP spacecraft. The mother/daughter portion of the mission consisted of two spacecraft (ISEE 1 and ISEE 2) with station-keeping capability in the same highly eccentric geocentric orbit with an apogee of 23 Earth radii. During the course of the mission, the ISEE 1 and ISEE 2 orbit parameters underwent short-term and long-term variations due to solar and lunar perturbations. These two spacecraft maintained a small separation distance, and made simultaneous coordinated measurements to permit separation of spatial from temporal irregularities in the near-Earth solar wind, the bow shock, and inside the magnetosphere. By maneuvering ISEE 2, the inter-spacecraft separation as measured near the Earth's bow shock was allowed to vary between 10 km and 5000 km; its value is accurately known as a function of time and orbital position.
The spacecraft were spin stabilized, with the spin vectors maintained nominally within 1 degree of perpendicular to the ecliptic plane, pointing north. The spin rates were nominally 19.75 rpm for ISEE 1 and 19.8 rpm for ISEE 2, so that there was a slow differential rotation between the two spacecraft. The ISEE 1 body-mounted solar array provided approximately 175 Watts initially and 131 Watts after three years, at 28 volts during normal operation. The ISEE 1 data rate was 4096 bps most of the time and 16384 bps during one orbit out of every five (with some exceptions).
Both ISEE 1 and ISEE 2 re-entered the Earth's atmosphere during orbit 1518 on 26 September 1987. Seventeen of 21 on-board experiments were operational at the end.
Nation: | USA / Europe |
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Type / Application: | Research |
Operator: | NASA / ESA |
Contractors: | |
Equipment: | |
Configuration: | |
Propulsion: | ? |
Power: | Solar cells, batteries |
Lifetime: | |
Mass: | 340 kg |
Orbit: | 763 km × 137531 km, 30.38° |
Satellite | COSPAR | Date | LS | Launch Vehicle | Remarks | |
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ISEE 1 (Explorer 56) | 1977-102A | 22.10.1977 | CC LC-17B | Delta-2914 | with ISEE 2 |