Japanese Probe to Halley's Comet
Courtesy of NASA's National Space Science Data Center


Sakigake 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 (4.4 million miles) on March 11, 1986. It carries three instruments to measure plasma wave spectra, solar wind ions, and interplanetary magnetic fields, all of which worked normally. The spacecraft is spin-stabilized at two different rates (5 and 0.2 rpm). It is 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 23 hours, 8 minutes, 47 seconds Japan Standard Time with a geocentric distance of 88,997 kilometers (55,303 miles). This was the first planet-swingby for a Japanese spacecraft. During the approach, Sakigake observed the magnetosphere. The second Earth swingby was on June 14, 1993, at 40 Earth radii, and the third on October 28, 1994 at 86 Earth radii.

Further mission planning targets a 23.6 kilometers (14.7 miles) per second, 10,000-kilometer (6,200-mile) flyby of Comet P/Honda-Mrhos-Pajdusakova on February 3, 1996 at about 21.00 GMT (approaching the nucleus along the tail) some 0.17 AU from the Sun, and a 14-million-kilometer (8.7-million-mile) passage of Comet P/Giacobini-Zinner on November 29, 1998.

The probe is operated by Japan's Institute of Space and Aeronautical Science.


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Views of the Solar System Copyright © 1997 by Calvin J. Hamilton. All rights reserved.