New Class of 'Easily Retrievable' Asteroids Discovered

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The Physics arXiv Blog for MIT Technology Review 2013-08-12 17:20:14 UTC

Asteroids that pass close to Earth have become the focus of increased attention in recent years, in part because of the potential threat they pose to humanity.

But they are also a potential boon. For decades, science fiction writers and various space scientists have pointed out that asteroids offer a huge untapped source of valuable resources.

Even if asteroid material is too expensive to bring home, it could provide the raw materials for rocket fuel and perhaps even rockets themselves to be manufactured in space. Many visionaries have greedily eyed these resources with the hope that a new gold rush is just around the corner.

Indeed last year, a company called Planetary Resources, funded by a high profile list of investors including Google's Executive Chairman Eric Schmidt and space entrepreneur Richard Branson, announced its intention to begin mining asteroids as soon as is feasible.

So finding target asteroids is hugely important. That's why Daniel Garcia Yarnoz and a team of researchers at the University of Strathclyde in the UK today describe an entirely new category of asteroid that is easy to capture.

Garcia Yunoz and his peers have searched through the current database of around 9,000 near-Earth objects, looking for those that they might maneuver into an accessible orbit by changing their velocities by less than 500 meters per second.

By accessible orbit, the researchers mean an orbit around the L1 or L2 Lagrangian points where the gravitational force of the Sun and Earth exactly balance. These points are about a million kilometers from Earth.

Garcia Yarnoz and co conclude that 12 asteroids meet this criteria. They call this new class of asteroid "Easily Retrievable Objects" or EROs and they make an interesting group.

The team says that one of these asteroids, with a diameter of between two and seven meters and known as 2006 RH120, could be sent into orbit around L2 by changing its velocity by just 58 meters per second. They calculate that this could be done with a single burn on February 1, 2021 and would take just five years to reach its destination.

In fact, they point out that with a low-thrust engine with a specific impulse of 3,000 s, it ought to be possible to move some 1,500 tons into orbit.

Of course, there are various concerns. Safety is obviously paramount, but the threat that accidentally sending an asteroid towards Earth poses is mitigated by the fact that it is only possible to move relatively small rocks with today's technology.

Then there is the problem of what to do with an asteroid orbiting L1 or L2. These orbits are highly unstable, so an asteroid would need to be constantly nudged to keep it on track. (Space scientists have already done this with many spacecraft such as the SOHO solar observatory, the Planck observatory and so on.)

None of the 12 ERO asteroids are new to astronomers; in fact, one of them became briefly famous when it was found to be temporarily orbiting the Earth until 2007. But until now, nobody had realized just how easily these bodies could be captured.

Of course, the list will grow in the coming years. Scientists believe there are millions of near-Earth objects, and most of the unknown ones are likely to be small and potentially mineable (since the bigger ones are easier to spot).

Image: NASA HQ PHOTO

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This article originally published at MIT Technology Review here

Topics: Asteroid, asteroid mining, Asteroids, space, Tech, U.S., US & World, World

MIT Technology Review is a Mashable publishing partner that identifies emerging technologies and analyzes their impact for technology and business leaders. This article is reprinted with the publisher's permission.