How real is the threat of an asteroid hitting Earth, and is there anything we can do to prevent it from happening? Asteroid impacts are nothing new. Only last year, one exploded over the city of Chelyabinsk in Russia injuring 1500 people and damaging some 7,000 buildings.
"It was a pretty nasty event, luckily nobody was killed, but it just shows the sort of force that these things have," says Alan Harris, Senior Scientist, DLR Institute of Planetary Research Berlin.
While there was surprise nobody saw it coming, the asteroid itself wasn’t that big, measuring no more than 20 metres across. It was tricky to spot, arriving into Earth’s atmosphere backlit by the Sun.
In fact, much bigger threats lurk out in space. Just a few days ago another asteroid 270 metres wide passed near Earth. That kind of object could cause much more damage.
"Something with the size of a hundred metres for instance, which still isn’t very big, you’re talking about something that would fit into a football field, and that could actually completely destroy an urban area in the worst case. So those are the things that we’re really looking out for, and that we’re trying to find ways to tackle," says Harris.
Action to address the asteroid threat is already underway. Earlier in February, space scientists and policy experts from all the major space-faring nations held talks to create a framework for action.
"Last year we were still in a situation where if an asteroid were threatening to impact on our planet we would not have the process in place to react to it. We made the first step to do that by establishing this group," Detlef Koschny from the European Space Agency said.
The group is backed by the United Nations, and while astronomers work to spot new asteroids near Earth, they also decide what we’d do if one turns out to be a serious threat.
It is estimated about 20,000 asteroids with diameters between a hundred metres and several tens of kilometres are orbiting near Earth
Specialists like Alan Harris are developing plans to help stop an asteroid on a collision course with our planet.
"So one of the main ideas we are considering is to simply hit the asteroid with a spacecraft, so it’s a little bit like cosmic billiards.
’'We want to change the orbit of an asteroid, and what we are doing basically is attempting to transfer momentum to it with a spacecraft.