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Key Dates:

  • 08.18.85: Launch
  • 03.08.86: Comet Halley Flyby
  • 02.28.98: End of Comet Mission
  • Status: Mission Complete

Scientific Instruments:

  1. Ultra-Violet Imager (UVI)
  2. Solar wind observation instrument (ESP)

Fast Facts:

  • Suisei means comet in Japanese. It was also the name of a Japanese World War II fighter (right).
  • Even though it kepts it distance from comet Halley, Suisei was still hit by dust particles.
  • Suisei was 1.4 kg (3 pounds) heavier than its sister spacecraft, Sakigake.

Mission Results:

Designed to study Comet P/Halley, Suisei was part of an internatinal fleet of six Halley's Comet explorers called the Halley Armada. Originally designated Planet-A, Suisei received its name (meaning Comet in Japanese) after launch. It was the second of two Japanese probes launched toward Halley during the 1986 encounter.

Launched on August 18, 1985 into heliocentric orbit, Suisei received course correction on 14 November 1985. On March 8, 1986, at 13:06 UT, SUISEI approached 151,000 km in the side of the Sun away from halley's Comet, returning ultraviolet images of the 20-million-kilometer hydrogen gas coma.

After the Halley encounter, in 1987, ISAS decided to send the spacecraft through an elaborate trajectory for an encounter with the Comet Giacobini-Zinner on 24 November 1998, thirteen years after launch. Fifteen burns of Suisei's 3 N motors over 5--10th of April 1987 yielded a 65 m/s velocity increase for a 60,000 km Earth gravity assist swingby on August 20, 1992, although the craft was then lost behind the Sun for the summer. Unfortunately, hydrazine for further corrections had been depleted by 22 February 1991. The planned encounter with Giacobini-Zinner (as well as a a far-distance flyby of Comet Tempel-Tuttle) had to be canceled on 28 February 1998; the cancellation formally ended the mission.

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