A Japanese space probe on a mission to bring back the world?s first rock samples from an asteroid failed to touch down yesterday on its target nearly 300 million km from earth. But scientists from the Japan Aerospace Exploration Agency (JAXA) were trying to pinpoint the location of the probe and considering a second attempt at landing.

The unmanned Hayabusa (?falcon?) had been scheduled to touch down on the surface of the 548-metre-long 25143 Itokawa for just one second after a voyage of two and a half years. ?I don?t think it landed?, project leader Junichiro Kawaguchi told a news conference.

Earlier in the day, the probe launched a landing target marker from a height of 40 metres, then descended to a position 17 metres from the asteroid, but apparently failed to complete its descent. ?From an engineering point of view, we see this as a success. We definitely want to try again?, Kawaguchi said

Scientists were in communication with the probe and analysing data to try to calculate its exact position, but it was unclear whether there had been a technical problem, an agency spokesman said. Hayabusa?s self-navigating system was programmed to abort the descent in the event that any of a number of factors appeared to put the probe in danger.

Asteroids are believed to contain rocks that have remained largely unchanged since the early days of the solar system and can thus offer valuable information about its origins. Information about structure could also be vital if an asteroid were found to be on a collision course with the earth. Hayabusa was to have landed on Itokawa for just long enough to allow it to fire a metal pellet into its surface and collect a sample of the material stirred up by the impact.

Hayabusa has already sent a series of detailed images of the asteroid, which the Japanese media noted looked something like a potato. They can be viewed on JAXA?s website.

Isabel REYNOLDS