|Mission type||Comet flyby|
|Mission duration||10 years and 10 months (launch date to date of last data transmission)|
|Launch mass||138.1 kilograms (304 lb)|
|Start of mission|
|Launch date||January 7, 1985, 19:27UTC|
|End of mission|
|Last contact||Data: November 15, 1995|
Beacon: January 8, 1999
|Perihelion altitude||0.92 astronomical units|
|Aphelion altitude||1.15 astronomical units|
|Flyby of 1P/Halley|
|Closest approach||March 11, 1986, 04:18 UTC|
|Distance||6,990,000 kilometres (4,340,000 mi)|
Sakigake (さきがけ, lit. "pioneer" or "pathfinder"), known before launch as MS-T5, was Japan's first interplanetary spacecraft, and the first deep space probe to be launched by any country other than the USA or the Soviet Union. It aimed to demonstrate the performance of the new launch vehicle, test the schemes of the first escape from the Earth gravitation for Japan on engineering basis, and observe space plasma and magnetic field in interplanetary space. Sakigake was also supposed to get references[clarification needed] for scientists. Early measurements would be used to improve the mission of the Suisei probe several months later.
Sakigake was developed by the Institute of Space and Astronautical Science for the National Space Development Agency (both of which are now part of the Japanese Aerospace Exploration Agency, or JAXA). It became a part of the Halley Armada together with Suisei, the Soviet/French Vega probes, the ESA Giotto and the NASA International Cometary Explorer, to explore Halley's Comet during its 1986 sojourn through the inner Solar System.
It carried out a flyby of Halley's Comet on March 11, 1986 at a distance of 6.99 million km.