Suisei was identical in construction and shape to Sakigake,but carried a different payload:a CCDUV imaging system and a solar windinstrument.[3]
The main objective of the mission was to take UV images of the hydrogen corona for about 30 days before and after Comet Halley's descending crossing of the ecliptic plane. Solar wind parameters were measured for a much longer time period.
The spacecraft is spin-stabilized at two different rates (5 and 0.2 rpm).[4]Hydrazine thrusters are used for attitude and velocity control;star and Sun sensors are for attitude control;and a mechanically despun off-set parabolic dish is used for long range communication.[2]
Launch
Suisei was launched on August 18,1985 by M-3SII launch vehicle from Kagoshima Space Center on M-3SII-2 mission. It was sent on an intercept course with Comet Halley,after which it would remain in a heliocentric orbit for later use as long as it was viable.[5]
Halley encounter
Suisei began UV observations in November 1985,generating up to six images/day. The spacecraft encountered Comet Halley at 151,000km on sunward side during March 8,1986,suffering only two dust impacts which tilted the craft by 0.72 degrees.[6][7] Suisei carried two instruments designed to study the growth and the decay of the cometary object's hydrogen corona,and the interaction of the solar wind with the cometary ionosphere.[8] These observed a peak in Comet Halley's hydrogen emissions every 53 hours.[7]
Earth flyby
Fifteen burns of Suisei's 3 N motors during the period of April 5–10,1987,yielded a 65m/s velocity increase for a 60,000km Earthgravity assist swingby on August 20,1992,although the craft was then lost behind the Sun for the summer.[2]
The hydrazine fuel was depleted on February 22,1991.[9] Preliminary tracking indicated a 900,000-km flyby of Earth had been achieved[2]
Other planned encounters
ISAS had decided during 1987 to guide Suisei to a November 24,1998,encounter with 21P/Giacobini–Zinner,but due to depletion of the hydrazine,this,as well as plans to fly within several million kilometers of Comet 55P/Tempel–Tuttle on February 28,1998,were cancelled.[9]
↑ K. Hirao; T. Iroh (1987). "The Sakigake and Suisei encounter with comet P/Halley". Astronomy & Astrophysics. 187 (1/2): 39. Bibcode:1987A&A...187...39H.
Payloads are separated by bullets ( · ), launches by pipes ( | ). Crewed flights are indicated in underline. Uncatalogued launch failures are listed in italics. Payloads deployed from other spacecraft are denoted in (brackets).
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