Can we really defend earth against an asteroid strike?

asteroid strike
Image credit | auntspray/

An asteroid strike of any significant size would almost certainly be the end of our time on earth. Maybe the end of the earth itself. After all, it took out the dinosaurs and affected the earth for many hundreds of years afterwards.

You will remember the Jerry Bruckheimer science fiction film Armageddon, starring Bruce Willis. A meteor shower destroys the space shuttle and scientists realise that an asteroid strike is 18 days away and it will be an extinction level event. You will perhaps not remember the more accurate rival Deep Impact, which – even with a great cast – did not fare so well at the box office. Both were released in 1998.

What was science fiction then is becoming science fact now.

Right now, in John Hopkins University Applied Physics Lab, scientists are working on an asteroid killer. Or at least an asteroid nudger. Known as DART, for Double Asteroid Redirection Test, this rocket is being designed to hit an asteroid and tilt it off course. It will be tested on an asteroid called Dimorphos (which is not on course to hit us) and will nudge it off course by a millimetre a second. This may not sound like much but given the relative speeds of everything in space, it should be enough to change the course of an asteroid sufficiently to miss us. It is, according to the initial discussions more than a decade ago, ‘like playing billiards in space’.

If it works, it is definitely comforting, as long as we have enough notice.

And that, of course, is the big question. One potential asteroid strike happened last year as a rock missed us by a mere 30,000 km, which in space terms means you feel the wind of the bullet. And they picked it up at the last minute.

We are, of course, lucky because of our huge neighbour Jupiter, whose vast gravity protects us from almost all asteroids, acting like a fishing net and without whom we would now be dust orbiting, well, probably Jupiter.

Asteroids are interesting not just because they could destroy us. There are plans afoot to land on them and bring back samples of strange new metals and minerals that could prove enormously beneficial.

The mysterious ‘Oumuamua that passed through our solar system a couple of years ago was deemed to be ‘alien’ in that no-one has yet figured out exactly what it was. It may be that we will see more of these types of phenomena.

It may be that alien civilisations are sending us the raw materials to escape from our parochial little solar system and join the party beyond the roiling turmoil in the gentle, civilised centre of our galaxy.

We just have to hope their aim is good, otherwise what we will see as an extinction event asteroid strike, they will see as ‘what a pity, they seemed such fun’.

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