Sakigake
Other Name(s)
National Affiliation: Japan
Launch Date/Time: 1985-01-08 at 19:26:00 UTC
Launch Vehicle: M-3SII
On-orbit dry mass: 138.10 kg
Nominal Power Output: 100.00 W
Description
Sakigake ('Pioneer') is a test spacecraft similar to Suisei (Planet-A). It
flew by Comet P/Halley on its sunward side at a distance of about 7 million
kilometers on March 11, 1986. It carried three instruments to measure
plasma wave spectra, solar wind ions, and interplanetary magnetic fields,
all of which worked normally. 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. Sakigake made an Earth swingby on January 8,
1992. The closest approach was at 23h08m47s (JST, = UTC+9h) with a
geocentric distance of 88,997 km. This was the first planet-swingby for a
Japanese spacecraft. During the approach, Sakigake observed the geotail.
A geotail passage occurred 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 remains 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 P/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 P/Giacobini-Zinner on Nov 29, 1998.
