Can we deflect an asteroid by crashing into it? Space engineering expert weighs in

The target asteroid is called Dimorphos, a body 163 metres in diameter that’s orbiting a 780 metre-wide asteroid called Didymos. This ‘binary asteroid system’ was chosen because Dimorphos is in orbit around Didymos, which makes it easier to measure the result of the impact due to the resulting change in its orbit. However, the Dimorphos system does not currently pose any risk to the Earth.

Regardless, NASA is attempting nothing less than a full scale planetary defence experiment to change an asteroid’s path. The technique being used is called ‘kinetic impact’, which alters the orbit of the asteroid by crashing into it. That’s essentially what is known as a safety shot in snooker, but played on a planetary level between the spacecraft (as the cue ball) and the asteroid.

A tiny deflection could be sufficient to prove that this technique can actually change the path of an asteroid on a collision path with the Earth.

But the Dart spacecraft is going to be completely blown apart by the collision because it will have an impact equivalent to about three tonnes of TNT. In comparison, the atomic bomb dropped on Hiroshima was equal to 15,000 tonnes of TNT.

So, with this level destruction and the distance involved, how will we be able to see the crash? Luckily, the Dart spacecraft is not travelling alone on its quest, it is carrying LICIACube, a shoebox-size mini spacecraft, known as a cubesat, developed by the Italian Space Agency and aerospace engineering company Argotec. This little companion has recently separated from the Dart spacecraft and is now travelling on its own to witness the impact at a safe distance of 55km.

Never before has a cubesat operated around asteroids so this provides new potential ways of exploring space in the future. The impact will also be observed from Earth using telescopes. Combined, these methods will enable scientists to confirm whether the operation has been successful.

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