THE international community is close to agreeing a strategy to combat the global threat of an asteroid hitting the Earth.
Last week, representatives from 30 governments met scientists to discuss what action, if any, is needed to deal with the threat. And for the first time, after decades of arguing and dithering, delegates spoke with one voice. 鈥淭here is now a consensus that the threat is real and mainly comes from mid-sized objects,鈥� says Lembit Opik, an amateur astronomer and British member of parliament, who attended the meeting held in Frascati, Italy.
Mid-sized asteroids are classed as those measuring between 200 metres and 1 kilometre across, and would be capable of destroying large cities or causing devastating tsunamis. The scientists recommended that the 30 nations, all members of the Organisation for Economic Cooperation and Development (OECD), should dedicate a round-the-clock network of telescopes to detecting and cataloguing all mid-sized rogue asteroids.
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So far most of the effort put into detecting near-earth objects (NEOs) has focused on spotting larger asteroids capable of causing mass extinctions. But these are rare, and there is little chance of one hitting us in the immediate future.
Yet up to 50,000 smaller, mid-sized asteroids are also hurtling around our Solar System, says Brian Marsden, director of the Smithsonian Astrophysical Observatory in Cambridge, Massachusetts. So far we have only spotted about 1700 of them.
To detect more, astronomers need to employ telescopes with 3-metre mirrors or bigger. But amateur astronomers, who have played a vital role in detecting the asteroids we know about so far, do not own such telescopes, which are in high demand by the professional community. Michael Oborne, director of the OECD鈥檚 Global Science Forum, says the next step is to work out if we need to build more, or can get by with what is available. It will cost money either way.
鈥淭he difficulty lies in convincing politicians to invest in something that has a low probability but very high consequences,鈥� says Crispin Tickell, a member of a British task force that has been lobbying the OECD to address the problem. The blueprint advocated by the scientists is our best chance of success, he says, and the OCED is one of the few organisations with the money and clout to make it happen.
鈥淚t is extremely gratifying that they are taking notice,鈥� he says. Science policy advisers to each of the governments will consider the proposals this week at a Global Science Forum meeting in Paris. However, it could still be years before any money is actually spent on a 24-hour surveillance network.
Supporters of the scheme say that the only way to accurately gauge the threat is to detect all of the asteroids and calculate their trajectories. Without this crucial first step, no government will seriously tackle the issue of how to deflect an incoming asteroid, or somehow mitigate the effects of its impact. When the time for action does come, it will be an unprecedented and hugely expensive international military exercise involving many countries, says Oborne.
Another long-term proposal put forward by the scientists in Italy was to establish a space-based detection system to spot comets entering our Solar System. Because we would have very little warning of a rogue comet鈥檚 approach, they may be even more dangerous than asteroids.