DEFENDERS OF EARTH

Meet the people who keep watch for world-ending asteroids

- GEORGINA TORBET

You’re woken in the middle of the night by an urgent phone call. An asteroid is headed straight for Earth and it's your job to find out if it'll strike the planet and rain destruction down upon us all.

It sounds like an overly-dramatic movie trailer, but that’s the real-life task of the people in the European Space Agency’s (ESA) Near-Earth Objects Coordination Centre, or NEOCC – a multidisciplinary centre staffed by astronomers, mathematicians and engineers who work on predicting asteroid impacts. People like Richard Moissl, Marco Fenucci and Dora Föhring (see ‘Meet the asteroid hunters’, p55). They're part of the dedicated team monitoring our skies to protect the planet from potential threats from above.

ON THE LOOKOUT

When it comes to defending a planet, the first step is finding out where the largest asteroids are.

“You can only do something to address a threat if you know about it,” Moissl says. “So the very first step in the whole chain is observations. You need to find the asteroids.”

The aim here is to identify any potential threats with as much advance warning as possible, so that there’s time to take action to protect us and the planet. For example, we could launch an intervention like NASA’s DART (Double Asteroid Redirection Test) mission in 2022, which saw a spacecraft deliberately crash into an asteroid to alter its course. With enough time, even a relatively small intervention such as this would be enough to deflect a very large, dangerous asteroid.

But if it helps to set your mind at ease, know that the vast majority of very large asteroids have already been located. “The kind of objects that we're really worried about are the ones that could destroy a city,” Föhring says. The advantage of searching for these objects, which are over 100m (almost 330ft) across, is that they’re big enough to spot easily. “These really dangerous ones, we think we've discovered 99 per cent of them.”