Do you think we should spend more on ‘safeguarding’ Earth from asteroid impacts?

Those risks are among the few that we can quantify. We know how probable impacts by rocks of different sizes are, and the biggest threat is from the rare big ones. I think if you do a normal calculation working out the probability and the consequences and what insurance premium you should spend to reduce that risk, you come up with a number like £100 or £200 million ($130 or $260 million) a year. That’s the kind of premium that would be worth spending to reduce the risk of an asteroid impact. It’s good that there is talk about doing this and spending money in two different ways.

One way is to do a more complete survey so that we can monitor the orbits of all the asteroids down to about 15 metres (49 feet) across – not just the very big ones – and so be alert to any that might be in orbits that could crash into Earth. The other is to think a bit more about the technology to deflect them if they do get too close. I think it’s worth some effort, but that risk doesn’t keep me awake at night.

Above: There are a large number of near-Earth objects that could cause harm to our planet