Gold Dust

The asteroid Itokawa from which the Hayabusa spacecraft has successfully returned sample material to Earth (Image: JAXA)

As you may remember, a couple of weeks back, the Japan Aerospace Exploration Agency (JAXA) announced that, after all, the Hayabusa spacecraft had collected extraterrestrial particles from the asteroid Itokawa.

This came as a bit of a shock to me. Why?

Well, earlier this year, at the Meteoritical Society meeting in New York, a Japanese colleague had told me the omens were not very good. He thought that they were only likely to find terrestrial particles. As he is normally someone with his finger on the pulse, I thought, well, that’s that then. Hayabusa, a sample return mission with no samples. Never mind, space exploration is a risky business, better luck next time. In hindsight, his comments were probably just natural caution. No point in getting people’s hopes up unnecessarily.

As outlined in an earlier blog entry, Hayabusa was a mission beset with difficulties. It only made it back to Earth, albeit three years late, due to the ingenuity and tenacity of the Japanese engineers. But all that is in the past. Hayabusa has been a remarkable achievement: the first mission that has successfully returned material from an asteroid.

Initial analysis of the particles collected from asteroid Itokawa indicates that they are similar in composition to the most common type of meteorite that arrives on Earth. These are known as ordinary chondrites. Remote observation of asteroid Itokawa had suggested that it was S-class, the group that was thought to be the source of ordinary chondrites. It seems that the Itokawa is going to confirm this theory. There is obviously still a lot of work to do, but it looks like the material brought back by Hayabusa is going to have profound implications for our understanding of where the meteorites that fall to Earth come from.

Not bad for a mission that nearly didn’t make it home. No wonder Junichiro Kawaguchi, the mission’s Project Manager, is quoted by the BBC as saying “I’m overwhelmed by emotion”.

But this is really just the start. The 1500 grains so far identified as extraterrestrial are going to be the subject of intense research in the coming years. A few surprises are certain.

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