Asteroid-Sampling Spacecraft Returning to Earth in June
An artist's concept of Japan's Hayabusa landing on the asteroid Itokawa.
Credit: Akihiro Ikeshita/JAXA.

A resilient Japanese space probe is on track to become the first spacecraft to return to Earth with pieces of an asteroid when it drops a sample canister in a deserted patch of the Australian outback in June.

Japan's plucky Hayabusa probe is slowly limping its way back to Earth despite several glitches since its 2005 rendezvous with the small potato-shaped asteroid Itokawa. It will drop a capsule containing the sample canister down on the Woomera Prohibited Area in the South Australian outback as part of an agreement between Australian authorities and the Japan Aerospace Exploration Agency (JAXA).

The Woomera Prohibited Area, which is managed by Australia's Department of Defense, is the largest land-based test range in the world.

"Australia is proud to support Japan in this world-first expedition," said Senator Kim Carr, Australia's Minister for Innovation, Industry, Science and Research.

Touching an asteroid

Hayabusa spent three months exploring the Itokawa asteroid in late 2005, even making an unplanned landing on the asteroid's surface. The probe spent up to a half-hour on Itokawa, making it the first spacecraft to lift off from an asteroid.

While telemetry showed that Hayabusa likely did not fire its projectile as planned while on Itokawa's surface, scientists are hoping that bits of dust or pebbles traveled through the probe's funnel and into its sample return capsule.

Hayabusa took approximately 1,600 pictures, collected about 120,000 observations of near-infrared spectral data and recorded 15,000 data points with its X-ray spectrometer to investigate Itokawa's surface composition.

Troubled mission

The 950-pound Hayabusa launched in 2003, but encountered a series of difficulties over the course of its troubled asteroid mission. Those setbacks included ion engine troubles, a fuel leak (during which ground controllers temporarily lost communication with the spacecraft), and loss of power in an electrical battery.

Each of the probe's four ion engines has experienced glitches, and in November 2009 JAXA officials were doubtful Hayabusa would ever be able to return to Earth.

But since then, Japanese engineers devised a plan that combined parts from two partially-failed engines to help Hayabusa maintain its current scheduled return.

These revised plans called for the beleaguered Hayabusa to continue thrusting its engines until March, after which its ion system would shut down and the probe would coast toward Earth. Hayabusa is then expected to jettison the onboard sample capsule so it can re-enter Earth's atmosphere and make a parachute landing in Australia.

Hayabusa's return to Earth was already postponed from its original 2007 timeline after the probe's departure from Itokawa was delayed a year due to the spacecraft's mechanical problems.

Japan's partnership with Australia for Hayabusa's return to Earth is an example of Australia's ongoing contribution to international space programs, Carr said.

"Australian authorities will assist JAXA in ensuring the recovery of the spacecraft on its return and are working closely with their Japanese counterparts on the proposed path and landing of Hayabusa," said John Faulkner, Australian Minister for Defense. "This has been an historic mission. It is the first time a spacecraft has made contact with an asteroid and returned to Earth."