Asteroids pose threat to Earth

It's official: the Earth is at risk from falling asteroids.

It's official: the Earth is at risk from falling asteroids.

A Government task force has concluded that the threat of asteroids crashing to Earth as portrayed in Hollywood movies Deep Impact and Armageddon is not the stuff of science fiction - it's very, very real.

The task force on Near Earth Objects (NEOs) will publish its findings later this month. It will confirm that there is a distinct possibility of asteroids and comets hurtling to Earth and will urge the Government to take a lead in seeking international action to avert the threat.

The recommendations include more work to identify the asteroids or comets that could present a risk, including building a new telescope, possibly in the southern hemisphere, to help to track the objects far out in space and to study the physical properties of NEOs.

"It says the threat is serious. There is absolutely no doubt about that at all, and it goes into a great deal of detail. It says the threat is significant enough to warrant action," said one source who has seen the report.

"A risk assessment shows that the risk from NEOs is up there with air crashes, train crashes, emissions from nuclear reactors like Chernobyl. It is above the line of tolerability set by the health and safety executive. If this threat was owned by somebody, it would be an offence - that is the sort of analogy that has grabbed the politicians."

Until recently the Government had been sceptical about the hazards but science minister Lord Sainsbury was persuaded to set up the task force in January following a campaign by scientific experts.

It marks a personal victory for the Liberal Democrat MP Lembit Opik, who has waged a lone campaign in the Commons for the issue to be taken seriously. "I don't think that people are laughing any more at the idea that NEOs are a real threat. Two or three years ago there was a high giggle factor about NEOs but in the last 18 months the scientific community and the general public have changed their view measurably. The popular media has woken up to the threat because of Deep Impact and Armageddon. It is literally a matter of life and death if there is an impact."

Mr Opik became fascinated with the issue because his grandfather, Ernst, was an astronomer who discovered a cloud of a trillion comets in the outer solar system. "It's called the Oort cloud but it was nearly called the Opik cloud," said the MP.

There has been growing acceptance that the dinosaurs may have been wiped out by a catastrophic asteroid or comet strike in the Gulf of Mexico. There is also evidence that more recent strikes on the Earth included one in 1904 that had the impact of a nuclear explosion in Tunguska, Siberia, felling huge areas of forest.

The most recent scare was raised in March 1998, when scientists identified an asteroid which they thought could hit the Earth in 2028. The asteroid's trajectory has since been dismissed as a "near miss" but it galvanised politicians to take the threat of objects falling from space more seriously.

The three-man working party, chaired by Dr Harry Atkinson, with Professor David Williams and Sir Crispin Tickell, consulted with leading experts in the UK, Europe and the United States when investigating the magnitude of the hazard and is understood to have delivered its report in July to Lord Sainsbury.

The team was told by experts that the US is already taking the threat seriously but closer observations were needed to fill gaps in the American checks on space. Nasa has been ordered to identify within the next decade all the large NEOs of more than 1km - just over half a mile - across which present a threat to Earth. British experts warned the committee that smaller objects may not obliterate the planet, but they could destroy whole cities.

The working party is understood to have agreed with the scientific experts that closer studies are needed, and it can be done only through international co-operation. It then leaves Tony Blair's government a headache: if they do find an asteroid or comet that may hit the Earth, what can they do about it?

Jonathan Tate, who runs Spaceguard, a voluntary group of experts dedicated to NEOs, said they could deflect the asteroids by attaching rockets to blast them out of the Earth's orbit. Another option would be to vaporise part of the object with a nuclear explosion in space.

Major Tate, who took up the issue after watching the Shoemaker-Levy comet, said: "One of the main things we have to do is educate the public. We now know that impacts have happened in the past and could affect the global environment. People are now looking back through history to see whether, for instance, an impact in 540 caused the Dark Ages. The global economy is pretty fragile - look what happened after the earthquake in Japan. That was peanuts compared to what would happen if an asteroid took out a major city and at the moment, we just don't know."