NASA has committed to an operation in which they will grab an asteroid and put it into lunar orbit in the 2020s, using a robotic system to throw a 12-metre-wide rock into a space shopping bag, and then tow it to the Moon. This seemingly useless mission is actually crucial to the survival of humankind.
The space agency calls it the Asteroid Redirect Mission. The image above shows how NASA envisions one of the missions after capture: it will send astronauts to the asteroid in an Orion spacecraft to take samples and return them to Earth. The rings on the bag are hooks for the astronauts to move safely across the asteroid’s surface.
NASA has two ideas in mind to capture the asteroid. The first is to “retrieve a large, boulder-like mass from a larger asteroid and return it” to lunar orbit. Imagine it: sending a robotic ship to rendezvous with an asteroid, have it remove a chunk that is about 12 metres in diameter, put it inside a bag, and tow it to the Moon. It seems awfully difficult and dangerous.
The easier alternative is to “capture and redirect an entire very small asteroid.” There’s only one problem with this, according to Paul Chodas, a senior scientist at JPL’s Near-Earth Object Program Office:
There are hundreds of millions of objects out there in this size range, but they are small and don’t reflect a lot of sunlight, so they can be hard to spot. The best time to discover them is when they are brightest, when they are close to Earth.