Technology & Science

Asteroid probe returns to Earth Sunday

Hayabusa — the Japanese probe launched seven years ago to try to capture the first samples from an asteroid — is on its way home and is due to land Sunday in South Australia.

Hayabusa — the Japanese probe launched seven years ago to try to capture the first samples from an asteroid  — is on its way home and is due to land Sunday in South Australia.

Touchdown for the craft's capsule is set for 10 a.m. ET Sunday — midnight local time — in a remote part of the Australian outback. The final trajectory correction took place Tuesday.

In this artist's rendering, the Hayabusa probe is above the surface of the asteroid Itokawa. ((Japan Aerospace Exploration Agency/File/Associated Press))

Hayabusa was launched in May 2003 on a mission to visit the asteroid Itokawa, a lump of revolving rock about 540 metres long. The asteroid was almost 300 million kilometres away from Earth at the time Hayabusa intercepted it in 2005.

Hayabusa successfully landed on the asteroid twice that year, but things didn't go as planned. Its attempt to fire a projectile into the asteroid surface to gather samples failed.

So it's not at all clear if the returning capsule will contain any asteroid dust in its collection canister. Scientists say the dust could help them gain new understanding of how the solar system formed.

Glitchy mission

Subsequent communication failures, fuel leaks, battery and engine problems forced Hayabusa to spend another three years in space when it missed its planned orbit return.

Finally, after a seven-year journey that spanned some two billion kilometres, it returns Sunday to a scientific community that's desperately hoping it was somehow able to capture something to analyze.

Even if the collection canister is empty, Hayabusa has already provided a wealth of data about the asteroid Itokawa. Aside from all the pictures it took, it analyzed the asteroid's terrain and gravity.

The Hayabusa mothership will be travelling at more than 12 kilometres a second when it hits the Earth's atmosphere. NASA engineers hope the fiery re-entry will help them understand what a craft returning from Mars would undergo.

"This is the second highest velocity re-entry of a capsule in history," said Peter Jenniskens, a scientist at NASA's Ames Research Centre. "Such man-made objects entering with interplanetary speed do not happen every day, and we hope to get a ringside seat to this one."

The 40-centimetre-wide containment capsule will separate from the main spacecraft well above the Earth's atmosphere. It will eventually deploy a parachute to help slow its landing. The capsule also has a radio beacon.

If all goes according to plan, researchers hope to recover it from the outback on Monday.