Status: Retired 1995. First Launch: 1985-01-07. Last Launch: 1995-01-15. Number: 8 . Payload: 800 kg (1,760 lb). Thrust: 1,930.00 kN (433,880 lbf). Gross mass: 61,700 kg (136,000 lb). Height: 27.80 m (91.20 ft). Diameter: 1.41 m (4.62 ft). Apogee: 1,400 km (800 mi).
LEO Payload: 800 kg (1,760 lb).
Sakigake ('Pioneer') was a test spacecraft similar to Suisei (Planet-A). Objectives were :verification of fundamental technology related to interplanetary missions, including deep-space communication, attitude control, attitude determination; study and observation of solar wind and plasma waves and interplanetary magnetic field. It carried three instruments to measure plasma wave spectra, solar wind ions, and interplanetary magnetic fields. The spacecraft was spin-stabilized at two different rates (5 and 0.2 rpm). It was equipped with hydrazine thrusters for attitude and velocity control, star and sun sensors for attitude determination, and a mechanically despun off-set parabolic dish for long-range communication. Launched into an initial heliocentric orbit with a period of 318.8 days, at 151.4 x 121.9 million km (0.815 x 1.012 AU), 1.439 degree inclination. Flew by Comet Halley on its sunward side at a distance of about 7 million kilometers on March 11, 1986. It later made an Earth swingby on January 8, 1992 with a closest approach of 88,997 km. This was the first planet-swingby for a Japanese spacecraft. During the approach, Sakigake observed the geotail, with passage occurring at 290 Re on 14 June 1993 before ISTP's multi-spacecraft investigation of that region. The second Earth swingby was on June 14, 1993 at 40 Re, and the third on October 28, 1994 at 86 Re. Almost no hydrazine remained so no further maneuvers were accomplished. Telemetry contact was lost on 15 November 1995 at a distance of 106 million km. Future mission planning had included a 23.6 km/s, 10,000 km flyby of Comet Honda-Mrkos-Pajdusakova on Feb 3, 1996 (approaching the nucleus along the tail) some 0.17 AU from the Sun, and a 14 million km passage of Comet Giacobini-Zinner on Nov 29, 1998.
Rendezvoused with comet Halley 3/8/86. Solar Orbit (Heliocentric). PLANET-A (SUISEI). Launch time 2333 GMT. Imaging of the hydrogen coma of Halley's comet by the hydrogen Lyman alpha line. Measurement of the solar wind in the cruising phase and in the vicinity of the comet. Launching organiza tion ISAS. Heliocentric orbit parameters 282 days, inclination 0.888 deg, 151.42 x 100.5 million km (1.0122 x 0.6718 AU).
MUSES-A was renamed Hiten after launch. It developed of lunar swingby techniques for future missions and ejected a lunar orbiter. Launching organization ISAS. On 1990 Jan 25: Period 6.665 days, inclination 30.63 deg, 262.49 x 286182.72 km. On 1992 Feb 17: Period 4.53 days, inclination 38.90 deg, perilune 2289.67 km, apolune 49013.93 km.
At first thought not to have reached orbit. Later the re-entry vehicle was discovered in Ghana having reentered and deployed its parachute on January 15. At T+103 sec, during the second stage burn, the vehicle veered off course. The payload service module entered a 110 x 250 km x 33 degree orbit, instead of the intended 270 x 380 km and re-entered on its second orbit. The re-entry capsule was found later in Ghana. A failure of the second stage attitude control system was blamed, although it was considered likely that the payload was too heavy for the vehicle, being twice the mass of earlier MU-3S payloads.