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 spacecraft
Mission typeComet flyby
COSPAR ID1985-001A Edit this at Wikidata
SATCAT no.15464
Mission duration10 years and 10 months (launch date to date of last data transmission)
Spacecraft properties
Launch mass138.1 kilograms (304 lb)[1]
Start of mission
Launch dateJanuary 7, 1985, 19:27 (1985-01-07UTC19:27Z) UTC
Launch siteKagoshima
End of mission
Last contactData: November 15, 1995 (1995-11-16)
Beacon: January 8, 1999
Orbital parameters
Reference systemHeliocentric
Perihelion altitude0.92 astronomical units
Aphelion altitude1.15 astronomical units
Inclination0.07 degrees
Period382.8 days
Flyby of 1P/Halley
Closest approachMarch 11, 1986, 04:18 UTC
Distance6,990,000 kilometres (4,340,000 mi)

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.


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


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

Halley encounterEdit

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

Giacobini-Zinner encounterEdit

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 missionEdit

Telemetry contact was lost on November 15, 1995, though a beacon signal continued to be received until January 7, 1999.[2][3]


  1. ^ "Sakigake" (PDF). NASA. Retrieved 2022-12-02.
  2. ^ "Sakigake - Japan ISAS Halley's Comet Mission Sakigake". Archived from the original on 2016-03-03. Retrieved 2010-02-01.
  3. ^ "Sakigake – NASA Master Catalog". Retrieved 2010-02-01.

External linksEdit