AUSTRALIA: Space rock passes through satellite belt

Astronomers around the world breathed a sigh of relief last Monday night when an asteroid passed within 12,000 kilometres of Australia, closer than communication satellites.

First observed by a dedicated telescopic asteroid tracker in the US on 22 June, the object was then observed by French astronomer Professor Klotz and PhD student Michael Todd, who remotely programmed it into the schedule for the Zadko Telescope at the University of Western Australia.

Director of the telescope, Associate Professor David Coward, said the asteroid - officially known as Near Earth Asteroid 2011MD - was identified as a tumbling, elongated 4-12 metre rock during a 40-minutes observation by Zadko over Australian skies. The Zadko telescope observations were the first to determine that the rock was rotating with a period of about 11 minutes.

"NASA said asteroids of the size of 2011MD come this close to Earth on average once every six years so it's a relatively rare event," Coward said. "2011MD was within the geosynchronous satellite belt, orbiting with our communications satellites and it could do a lot of damage if it collided with one."

A visiting astronomer at the university, Professor Michael Boer from the Observatoire de Haute Provence in France, said: "If it were to enter the Earth's atmosphere there would be a big bang and it would probably explode. An asteroid that exploded over Russia in 1908 flattened a forest.

"A bigger space rock - say one of 100 metres - could destroy cities so it's important that we track them and that we pick them up early so we can have a worldwide coordinated warning system if necessary. We don't want to detect them 24 hours before they get close. There are more space rocks up there, we've just have not found them yet.

Boer said the Zadko played an important role in monitoring the skies above Western Australia and was part of a worldwide programme.