Most of the discussion about near Earth asteroids focuses on whether they represent a threat to Earth and what to do take if they turn out to be heading our way.

But today, Hexi Baoyin and pals at Tsinghua University in Beijing offer a different take. The question they ask is how to place an asteroid in orbit around the Earth.

Their conclusion is a little surprising. They say it’s relatively straightforward to nudge a small asteroid in our direction. They’ve even discovered a number of candidates nearby that we might want to bring as little closer.

Their inspiration is a phenomenon that astronomers have noticed with Jupiter. Every now and again, the gas giant captures a nearby object, which hangs around for a few years and then wanders off into space.

A good example is the comet Oterma which went into orbit about Jupiter in1936 before heading off into the Solar System two years later.

Could a similar thing happen to Earth, ask Baoyin and co. Having studied the orbits of the 6000 known near Earth objects (NEO), they say the short answer is no. None of them will come close enough for Earth to capture.

However, a few of these objects will come maddeningly close. So near, in fact, that a small nudge would send them into Earth orbit. “When such an NEO approaches Earth, it is possible to change its orbit energy…to make the NEO become a small satellite of the Earth,” they say.

A particularly good candidate is a 10-meter object called 2008EA9 which will pass within a million kilometres or so of Earth in 2049. 2008EA9 has a very similar orbital velocity as Earth’s. Baoyin and co calculate that it could be fired into Earth orbit by changing its velocity by 410 metres per second. That’s tiny.

This nudge should place the asteroid in an orbit at about twice the distance of the Moon. From there it can be studied and mined, they say.

Just like Oterma’s, this orbit is likely to be temporary so 2008EA9 will probably wander off into the heavens after a few years.

Interesting idea. What could possibly go wrong?

Ref: arxiv.org/abs/1108.4767: Capturing Near Earth Objects