TOKYO — A Japanese spacecraft on an unprecedented mission to bring asteroid material back to Earth is set to start home, despite showing signs of trouble earlier, an executive of the Japan Aerospace Exploration Agency (JAXA) said yesterday.
On Saturday, the Hayabusa probe apparently landed on the asteroid Itokawa and collected surface samples. After the landing, the probe hovered about three miles from the asteroid and appeared to be shaking, JAXA said, possibly because of a gas leak from a thruster.
The probe shut down all its engines Saturday and switched to solar power while JAXA investigated the problem.
But the probe appears to be stabilizing, and JAXA plans to reignite its engines by Dec. 10 for the return journey, said agency executive Yasunori Matogawa.
“We will meet that deadline, whatever happens,” Mr. Matogawa said.
If the agency fails to meet the deadline, it would be two more years before the probe — orbiting the sun between Earth and Mars alongside the asteroid — would be in the right position to return, he said.
JAXA said the Hayabusa appeared to have touched down for a few seconds on the asteroid about 180 million miles from Earth, collecting powder from its surface before lifting off again to transmit data to mission controllers.
But the agency will not know for sure whether Hayabusa collected surface samples until it returns to Earth. The probe, launched in May 2003, is expected to land in Australia in June 2007.
If all goes well, it will be the first time a probe returns to Earth with samples from an asteroid, according to JAXA. A NASA probe collected data for two weeks from the asteroid Eros in 2001, but it did not return to Earth.
The landing on the asteroid was Hayabusa’s second this month, after a faulty touchdown. JAXA lost contact with the probe during that attempt and did not even realize it had landed until days later — long after it had lifted off.
Scientists hope examining asteroid samples will help unlock the secrets of how celestial bodies formed. Asteroid surfaces are thought to have remained relatively unchanged over the eons, unlike larger bodies such as planets and moons.
In addition to recovering samples from the asteroid, the probe is testing a type of ion engine that uses an electric field to accelerate positive ions to a high velocity. JAXA hopes to use the fuel-saving technology in missions farther into space, its Web site said.
The Hayabusa mission is part of Japan’s efforts to expand its space-exploration program. JAXA said this year that it would send its first astronauts into space and set up a base on the moon by 2025.