Wilson da Silva

Science journalist, feature writer and editor.

Oct 12, 1996
Published on: New Scientist
1 min read
A solar system map showing hundreds of thousands of asteroids orbiting the inner planets

Wilson da Silva, Canberra

THE first truly global effort to detect and track thousands of asteroids with the potential to strike the Earth is about to crash just as it was getting off the ground. 

The asteroid watch programme for the southern skies, run by three Australian astronomers, will come to a halt at the end of the year when funding from the Australian government runs out. This programme is an essential part of the international project.

Duncan Steel, who runs the Australian asteroid tracking programme, told the ANZAAS meeting that the average risk of being killed by an asteroid strike is 1 in 5000. This figure is based on an asteroid at least a kilometre-wide crashing into the Earth, an event that is estimated to happen once every 100 000 years. When it does happen, however, the death toll is so high that it skews the odds.

But a much smaller object slamming into the biggest target on Earth—the Pacific Ocean—could devastate the countries of the Pacific Rim. 

“You only need a 100 to 200-metre object, even if it blew up in the atmosphere over the Pacific, to generate a blast wave that would cause a tsunami 100 metres high with a range of 1000 kilometres,” said Steel. “It would spread out and wipe out every single city in the Pacific Rim. The chances of that occurring in the next century are better than 1 in 100.”

The Australian tracking programme consists of three nights of observation a month with the Schmidt wide-aperture telescope at the Siding Spring Observatory in New South Wales. Once they spot an asteroid, the Australians notify theInternational Astronomical Union’s Minor Planet Center in Cambridge, Massachusetts, which passes on the information to other programmes in the northern hemisphere.

Other astronomers then track the asteroid during their night, helping to build up an accurate picture of its orbit. When northern observatories discover a new asteroid, they notify the Australians, who track it during their hours of darkness.

The Australians have discovered 10 per cent of all Earth-crossing asteroids since the programme began in 1990, and are responsible for a third of all the asteroid-tracking data produced.

The University of Arizona has run an asteroid-tracking programme in tandem with the Australians for several years, while a multimillion dollar joint project between the US Air Force and NASA’s Jet Propulsion Laboratory has juststarted up in Haleakala on the Hawaiian island of Maui. But now the Australian funding—which amounts to just £50 000 a year—is being withdrawn.

Steel says he would prefer not to be running the programme at all. He believes it should be the responsibility of the defence department. Either way, the worldwide effort is now in danger of falling apart because of Canberra’s short-sightedness, he said. The Australian government, determined to reduce its budget deficit, has trimmed science programmes across the board. 

“If, having realised the danger is there, we do not take steps to ascertain whether animpact is due within the next century, this could prove to be the greatest act of folly ever perpetrated by humankind.”