Astronomy:Sakigake

Short description: Japanese deep space probe launched in 1985

Sakigake

Sakigake spacecraft
Mission type	Comet flyby
Operator	ISAS
COSPAR ID	1985-001A
SATCAT no.	15464
Mission duration	10 years and 10 months (launch date to date of last data transmission)
Spacecraft properties
Launch mass	138.1 kilograms (304 lb)
Start of mission
Launch date	January 7, 1985, 19:27 (1985-01-07UTC19:27Z) UTC
Rocket	Mu-3SII
Launch site	Kagoshima
End of mission
Last contact	Data: November 15, 1995 (1995-11-16) Beacon: January 8, 1999
Orbital parameters
Reference system	Heliocentric
Perihelion altitude	0.92 astronomical units
Aphelion altitude	1.15 astronomical units
Inclination	0.07 degrees
Period	382.8 days
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', '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 its ability to escape from Earth gravity, and observe the interplanetary medium and magnetic field. Sakigake was also supposed to act as a frame of reference for data received from probes that flew closer to Halley's Comet. Early measurements would be used to improve the mission of the Suisei probe launched 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 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.

Design

Unlike its twin Suisei, it carried no imaging instruments in its instrument payload.

Launch

Sakigake was launched January 7, 1985, from Kagoshima Space Center by M-3SII launch vehicle on M-3SII-1 mission.

Halley encounter

It carried out a flyby of Halley's Comet on March 11, 1986 at a distance of 6.99 Gm.

Giacobini-Zinner encounter

There were plans for the spacecraft to go on to an encounter with 21P/Giacobini-Zinner in 1998 but the flyby had to be abandoned due to lack of propellant.

End of mission

Telemetry contact was lost on November 15, 1995, though a beacon signal continued to be received until January 7, 1999.

External links

• Sakigake
• Sakigake Mission Profile by NASA's Solar System Exploration
• Halley's Comet Flyby
• Sakigake Mission Comet Halley Data Archive at the NASA Planetary Data System, Small Bodies Node