The asteroid Itokawa, which to Japanese rocket scientists looks like a sea otter with its head in the foreground and its body fading into the darkness.

Credit: JAXA

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SYDNEY, 2 June 2006 - A Japanese team of researchers has made close-up observations and landed on an asteroid, describing its shape as that of a "sea otter".

The researchers, led by Akira Fujiwara of the Japanese space agency, JAXA, said the asteroid, named Itokawa, had a long, rounded section topped with a spherical section, making it look like the body and head of some kind of animal. When the scientists discovered a boulder on the asteroid's 'belly' they immediately thought of a sea otter.

Sea otters live in kelp forests in the Pacific Ocean, including off the coast of Japan. The charismatic animals often rest a rock on their belly which they use to smash open shell-fish.

Publishing a series of papers in the U.S. journal, Science, the team said the aim of their mission was to prove that it is possible to build a spacecraft that can hover over an asteroid, land on its surface and then return home to Earth.

Using ion engines, the Hayabusa craft rendezvoused with Itokawa on 12 September 2005. Its hovering phase was successful, as were two landings on the asteroid. However the scientists reported that the second of the sampling missions failed.

Its journey outward also left the craft low on fuel. Hayabusa was expected back on Earth in 2007, but coasting at a slower, but more fuel efficient speed, it is now due to return to Earth, dropping its cargo capsule into the Australian desert, in 2010.

Itokawa is an S-type asteroid, which spectral analysis reveals as being comprised mostly of silicates and iron. The samples aim to confirm the spectral results, and provide information on the possible origins of such a class of asteroid.

"The results obtained for Itokawa make a good benchmark for this type of asteroid. We could say that we have seen real images of the most common type of asteroid in the near-Earth region," said Fujiwara.

The scientists also confirmed that the asteroid is a loose assemblage of rubble, which was expected for this type of asteroid.