Jagged shadows highlight the boulders of Itokawa
Jagged shadows highlight the boulders of Itokawa

Somewhere in the rocky desert of the Woomera Prohibited Area, the capsule from Japan’s asteroid probe Hayabusa awaits the recovery teams.

It may contain traces of material from the surface of Itokawa, an asteroid that may because of its orbit, collide with earth in the future.

Hayabusa's shadow falls beside a circled reflective target it dropped as a guide for its sample recovery approach
Hayabusa's shadow falls beside a circled reflective target it dropped as a guide for its sample recovery approach. The probe touched the asteroid twice, once for 30 minutes but it isn't known if any material was successfully captured by the chamber that returned to Earth last night.

Hayabusa re-entered the atmosphere as a spectacular fireball in the middle of the night.

[youtube]http://www.youtube.com/watch?v=HpuU1hd_xeY[/youtube]

The YouTube above was taken from a NASA DC-8 near the predicted final trajectory for the space craft. As Hayabusa begins to break up the re-entry resistant sample collection component can be seen detaching and dropping below the blazing wreckage and is then tracked as it falls  toward the ground.

But where has Hayabusa been?

As this collection of images show, Itokawa is not a dense metallic rock asteroid, as some are known to be, but an aggregate of loose rubble and dust, including some boulders tens of metres across.

This scale comparison with the ISS was made in 2006, and the space station is now much larger. However 80 metres is slighly wider than the wingspan of an Airbus A380.
This scale comparison with the ISS was made in 2006, and the space station is now much larger. However 80 metres is slighly wider than the wingspan of an Airbus A380.

Itokawa comprises two visible lobes linked by a very fine grained area. Could it be two asteroids that ground together at some stage in a low speed collision? Does it contain individual denser components the size of the 30 metres wide shard from dead Comet Encke which is believed to have been the cause of the destructive Tunguska fireball of 1908 in central Siberia? Might it be a relic of the event that tore the moon from a larger planet Earth when the solar system, now middle aged, was young and chaotic?

We don’t know. Yet.

By getting to Itokawa, taking images, and demonstrating a rendezvous and sample retrieval technique, Hayabusa, one of the innovative probes launched by Japan’s space program, has brought some of the answers closer.

A close up of a single metre wide sample of the asteroid surface
A close up of the asteroid surface showing grains as small as 6 mm.
Hayabusa mapped most of the asteroid in detail, shown here in the hues astronauts would see
Hayabusa mapped most of the asteroid in detail, shown here in the hues astronauts would see
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