A tiny heatproof capsule which scientists hope contains some of the oldest dust in the universe will streak back to Earth and land in the Australian Outback on Sunday, ending a historic space mission
Scientists hope the Hayabusa craft, which left Earth in 2003 and reached the potato-shaped Itokawa asteroid two years later, will bring back dust gathered from the asteroid, possibly holding clues to the origins of the solar system.
If successful, the Japanese spacecraft will become the first to make contact with an asteroid and return to Earth.
Yoshiyuki Hasegawa, associate executive director of Japanese space agency JAXA, said the weather was excellent for the re-entry of the craft, which will jettison the capsule containing the hoped-for dust before it hits the atmosphere.
|This rendering picture released by the Japan Aerospace Exploration Agency shows the space probe Hayabusa|
Hasegawa said the mission was progressing well, but admitted that he was "very nervous about the capsule", which is due to land in the restricted military zone of Woomera in the remote South Australian desert.
"Today is very exciting and the greatest moment for us," he told reporters.
The Hayabusa has suffered a series of technical mishaps during its seven-year, five-billion-kilometre (three-billion-mile) space odyssey, leaving it limping home on limited power some three years late.
And after a malfunction with a system designed to stir up dust while the craft was on the asteroid, scientists from JAXA are uncertain what, if anything, the sample canister will contain.
If all goes to plan, the heat-resistant capsule will break apart from the craft about three hours before the scheduled re-entry shortly before midnight (1400 GMT) and rocket through at about 12.2 kilometres per second.
Meanwhile, the car-sized Hayabusa craft is expected to disintegrate as it hits the atmosphere, burning brighter than Venus as it explodes in temperatures hotter than the surface of the sun.
Scientists hope the capsule, about the size of a basketball, will float to earth on a parachute which should deploy about 10 kilometres above the surface, setting off a tracking beacon which will indicate its position.
"It's a great story, it has gone through so many trials and tribulations," said Australia's Parliamentary Secretary for Innovation and Industry Richard Marles.
"Actually, to be able to bring it back to the planet -- late, but better late than never -- it really is a miraculous achievement."
Hayabusa, designed to test the practicality of bringing back samples from celestial bodies, found that Itokawa was between "several tens of millions and hundreds of millions" years old, and had likely broken away from an ancient celestial body formed in the solar system's most primitive stages.
An international team of scientists has gathered in Woomera to witness the craft's spectacular re-entry and will take a helicopter to recover the capsule, which will be taken back to Japan for analysis.
Local Aboriginal tribespeople will accompany officials in their search for the precious cargo to ensure no damage is done to sites sacred to their ancient culture, which stretches back more than 40,000 years.