Is Earth really safe from killer asteroids?
Scientists say there’s a one in 100 chance of a 140m asteroid hitting Earth every century, but don’t worry, Nasa’s on it
In April, scientists discovered an asteroid that had a roughly one in 2,500 chance of colliding with Earth in six months. As the weeks passed and observations improved, they determined the space rock — perhaps 670m across — was on target for central Europe, potentially putting a million people in harm’s way. Scientists, space agencies and civil-defence organisations scrambled to find a life-saving solution, but soon determined it was too late.
“The exercise played out that we basically had to take the hit,” said Lindley Johnson, Nasa’s planetary-defence officer. Fortunately, that’s all it was: an exercise. But next time might not be. Scientists estimate there’s roughly a one in 100 chance of an asteroid larger than 140m across hitting the Earth every century. Depending on where such a rock landed, it could cause casualties exceeding any known natural disaster.
The good news is Nasa has a plan for such a scenario. Later this month, the US space agency will launch Dart (or the Double Asteroid Redirection Test), a mission that will test technologies designed to divert dangerous space objects. The bad news is that intercepting a killer asteroid could be a far harder, and more expensive, undertaking...