Hayabusa
The first asteroid sample ever returned, which proved where ordinary chondrites come from.
Key facts
- Agency
- Japan Aerospace Exploration Agency (JAXA)
- Type of mission
- Asteroid sample return
- Target
- Asteroid 25143 Itokawa
- Launched
- 9 May 2003
- Samples returned
- About 1,500 tiny grains
- Status
- Completed 2010
Hayabusa, meaning peregrine falcon, reached the small near-Earth asteroid Itokawa in September 2005. Itokawa is only about 535 metres long, shaped like a sea otter or a peanut, and is a rubble pile with no large craters, covered in boulders and patches of gravel.
A troubled journey
The mission nearly failed many times. Two of its three reaction wheels broke, a small rover called MINERVA missed the surface and drifted away, a fuel leak sent the craft tumbling, and contact was lost for weeks. During two brief touchdowns in November 2005, the device meant to fire a pellet into the surface probably did not work. Yet the team nursed the craft home with its ion engines, and its capsule landed in the Australian outback on 13 June 2010.
What was inside
The capsule held about 1,500 grains of dust, most smaller than a tenth of a millimetre, kicked up during the landings. They were analysed grain by grain.
The grains are made of olivine, pyroxene, plagioclase feldspar, troilite and iron-nickel metal in the same proportions and with the same chemistry as LL chondrites, a group of ordinary chondrites. That settled a long debate: the common S-type asteroids, whose light had looked a little different from ordinary chondrites, really are their source. The difference comes from space weathering, the slow darkening and reddening of an airless surface by the solar wind and micrometeorites, and the grains showed exactly that weathering on their rims.
Key dates
| Date | What happened |
|---|---|
| 9 May 2003 | Hayabusa launched on an M-V rocket. |
| 12 September 2005 | Arrived at the asteroid Itokawa. |
| 20 November 2005 | First touchdown on Itokawa. |
| 26 November 2005 | Second touchdown, when dust entered the sample catcher. |
| 13 June 2010 | The sample capsule landed at Woomera, Australia. |
See where this mission fits among all the others in the mission timeline.
Did you know?
Hayabusa was the first spacecraft to land on an asteroid and take off again.
The grains showed that Itokawa is slowly losing its surface dust to space, so small asteroids can change within a few million years.