ISEE-3 / ICE
ISEE-3 / ICE — NASA's International Sun-Earth Explorer 3 (launched 12 August 1978), the first spacecraft placed in orbit around a libration point: the Sun–Earth L1 point, in November 1978. Renamed the International Cometary Explorer, it became the first spacecraft to fly past a comet, Giacobini–Zinner, on 11 September 1985, and measured the solar wind upstream of Halley's comet in March 1986. (Shown representatively at L1, its home from 1978 to 1982.)
Key facts
Mission & specifications
Mission
- Operator
- NASA
- Launched
- August 12, 1978
- Status
- Completed
Trajectory
- Distance from the Sun
- 0.998 AU
- Computed from the cached position
- Distance from Earth
- 4,087,868 km
- Computed from cached positions
- Distance from Venus
- 0.281 AU
- Computed from cached positions
Mission
ISEE-3 was the third of the International Sun-Earth Explorers: ISEE-1 and ISEE-2 flew close together through Earth's magnetosphere, while ISEE-3 watched the solar wind coming toward it. Launched on 12 August 1978, it entered a halo orbit around the Sun–Earth L1 point on 20 November 1978 — the first spacecraft ever placed in orbit around a libration point, a place in space rather than a body. On 10 June 1982 it left L1 on a long and intricate path: several passes through Earth's magnetic tail and five lunar flybys, the last of them 119.4 km above the Moon on 22 December 1983, which threw it out of the Earth–Moon system. Renamed the International Cometary Explorer, on 11 September 1985 it flew through the tail of comet Giacobini–Zinner, about 7,800 km behind the nucleus — the first spacecraft to fly past a comet — and on 28 March 1986 it measured the solar wind 40.2 million km sunward of Halley's comet. NASA ended its operations on 5 May 1997, but the spacecraft kept orbiting the Sun and came back past Earth in 2014. A private team, the ISEE-3 Reboot Project, re-established contact in May 2014 and in July fired its thrusters for the first time in 27 years, but the burn meant to return it to L1 failed, apparently because the nitrogen that pressurised its fuel had run out. It passed the Moon on 10 August 2014 — 16,663 km above the surface in JPL's reconstruction, about 15,600 km on NASA's mission page — and was last heard from in September 2014.
- 1978ISEE-3 launches on a Delta rocketLaunch
The third International Sun-Earth Explorer.
- 1978The first spacecraft at a libration pointArrival
Enters a halo orbit around the Sun–Earth L1 point.
- 1982Leaves L1Milestone
For passes through Earth's magnetic tail and five lunar flybys.
Through the tail of comet Giacobini–Zinner, as the International Cometary Explorer.
Measures the solar wind on the comet's sunward side.
- 1997Operations endMission end
NASA ends support; the spacecraft keeps orbiting the Sun.
After a private team re-established contact; the burn meant to return it to L1 had failed.
Images
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