Apophis: New European space mission could get up close with a large asteroid set to brush by Earth

The European Space Agency has given the go-ahead for initial work on a mission to visit an asteroid called (99942) Apophis.

- OR GRAUR

If approved at a key meeting next year, the robotic spacecraft, known as the Rapid Apophis Mission for Space Safety (Ramses), will rendezvous with the asteroid in February 2029.

Apophis is 340 metres wide, about the same as the height of the Empire State Building. If it were to hit Earth, it would cause wholesale destruction hundreds of miles from its impact site. The energy released would equal that from tens or hundreds of nuclear weapons, depending on the yield of the device.

Luckily, Apophis won't hit Earth in 2029. Instead, it will pass by Earth safely at a distance of 19,794 miles (31,860 kilometres), about one-twelfth the distance from the Earth to the Moon. Nevertheless, this is a very close pass by such a big object, and Apophis will be visible to the naked eye.

NASA and the European Space Agency have seized this rare opportunity to send separate robotic spacecraft to rendezvous with Apophis and learn more about it. Their missions could help inform efforts to deflect an asteroid that threatens Earth, should we need to in future.

The threat from asteroids

Some 66 million years ago, an asteroid the size of a small city hit Earth. The impact of this asteroid brought about a global extinction event that wiped out the dinosaurs. Earth is in constant danger of being hit by asteroids, leftover debris from the formation of the solar system 4.5 billion years ago. Located in the asteroid belt between Mars and Jupiter, asteroids come in many shapes and sizes. Most are small, only 10 metres across, but the largest are hundreds of kilometres across, larger than the asteroid that killed the dinosaurs.

The asteroid belt contains 1-2 million asteroids larger than a kilometre across and millions of smaller bodies. These space rocks feel each other's gravitational pull, as well as the gravitational tug of Jupiter on one side and the inner planets on the other.