Astronomers at Queen's University are keeping track of asteroids in the Earth's orbit that could pose a real threat to our planet, writes John Moore.
In the film Armageddon, Bruce Willis saves the planet by successfully blowing up a giant asteroid set on a collision course with Earth. While his dramatic rescue of the planet is decidedly fanciful, the fact remains that such threatening objects do exist and some day one is guaranteed to strike us.
To help prepare for the next one, astronomers at Queen's University Belfast have started monitoring rogue asteroids using the new Faulkes telescope in Hawaii. Their research may some day protect us from such catastrophic events in the future.
Millions of asteroids normally reside between Mars and Jupiter. However, every now and again some deflect out of their normal orbit and cross into Earth's orbit, producing what are called Near Earth Objects (NEOs).
More than 3,000 NEOs have been catalogued so far and each month 30 to 40 new ones are discovered. Approximately 700 of them have diameters greater than one kilometre, a body that on impact with the Earth would release the energy equivalent of 10 million times the power of the atomic bomb that razed Hiroshima.
"These NEOs are usually found by large observing surveys co-ordinated in America," says Dr Alan Fitzsimmons, project leader of the Queen's group using the Faulkes telescope. "However, the American telescopes can't track them after they become too faint to see, and that's when we start observing," he says.
"The Faulkes two-metre sized mirror can see to very faint levels in a very short space of time," says Fitzsimmons. "We know from previous orbital measurements that some of these NEOs could pass close to Earth within the next hundred years or so, and so we track them to improve the measurements."
All their data is sent off to the Minor Planet Centre (MPC) in Cambridge, Massachusetts, where all worldwide observations are reported. There, the data is processed and archived for future reference.
While most of Dr Fitzsimmons's efforts will be spent tracking the NEOs, he will also take photometric observations that might tell the astronomers what the object's constituent properties are. Approximately one in six asteroids are solid rock which, when travelling at high speeds, gives them tremendous kinetic energy should they threaten the Earth as an impactor.
"These measurements are very important, as they might help us deal with a threatening asteroid in the future," says Fitzsimmons. "We just don't know how a nuclear explosion might react with the object and nudge one away. Some interaction with the surface is necessary, so we need to know their make-up. Larger objects a kilometre in size pose the most threat. However, for each big one there are thousands of small ones, and more than likely it's one of those that could hit us," he adds.
In 1908, a small object just 50 metres across detonated above a remote region in central Siberia and levelled a forest, flattening everything over a 40-kilometre radius. If it had happened over central Dublin, the entire city would have been flattened.
But Fitzsimmons isn't too worried right now. Two or three objects with a small chance of collision in the future are being tracked, he says, yet the odds of them striking are so small you would have a better chance of winning the lottery.
"The new Faulkes facility isn't only for the professionals," says Jay Tate, director of Spaceguard UK, which acts as a national centre on the threat posed by potential collisions with asteroids and comets.
"School children in the UK now have a chance to carry out serious observations, and already one school has produced results that the MPC accepted. Even Northern Ireland schools now have the Faulkes facility as part of their curriculum," he says.
So far Earth has had a long run of good luck, but the statistics show that a major impact is imminent. The question is when, where and how do we deal with it?