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A manned mission to an asteroid has been bandied about for a while as the next big human spaceflight venture. But getting to an asteroid is tricky. They’re small and quick, making it complicated (though not impossible) to reach one and land on its surface.
A team of scientists at the Keck Institute for Space Studies in California have come up with a novel way to simplify the problem: why not bring the asteroid close to us? A asteroid orbiting the Moon would be easier to get to than one orbiting the Sun. Turns out, NASA is considering this audacious proposal. Looks like our Moon might be getting a companion in the coming years.
Keck scientists are proposing an almost science fiction-type mission: capture an asteroid and drag it into the Moon's orbit. A slow-moving spacecraft launched on an Atlas V and propelled by solar-heated ions could make its way to a target asteroid, maybe something about 23 feet wide weighing a moderate 1.1 million pounds. After briefly studying it to make sure it’s the right one to bring home, the robotic craft could autonomously catch the rock in a bag measuring about 32 by 50 feet. Once bagged, the spacecraft would travel back to the Moon and place the asteroid into a high lunar orbit.
According to the team, if they started right now we could have an asteroid in lunar orbit by 2025, and all for just $2.6 billion. That means this proposed mission is just slightly more expensive and on a slightly longer timescale than NASA’s Curiosity rover’s journey from concept to Mars. And think – we’re not going to the target, the target’s coming to us!
There are some obvious advantages to having an asteroid in lunar orbit. The Keck team sites the potential science benefits of having a nearby source of minerals and elements to both study and exploit on Earth and the ease of getting to something in the vicinity of the Moon. The asteroid could also serve as a practice spot for future lunar landings (though the Apollo astronauts taught us that practice on Earth is more than enough).
Moving as asteroid like this could teach us a lot about dealing with other threatening space rocks. It’s fair to say that if we can bring an asteroid close to Earth, we can move one further away from the planet. Learning how to change these rocks’ orbits could save us from being wiped out like the dinosaurs.
Of course, the obvious question is what happens if it all goes wrong and the asteroid doesn’t end up in lunar orbit but on a collision course with the Earth. It won’t. The Keck team dealt with that line of questioning. The asteroid type they propose moving is the type that regularly burns up in the Earth’s atmosphere, so if it did collide with the planet we wouldn’t feel a thing.
They also have their proposed spacecraft following a “non-impact trajectory,” meaning that if they did lose control of the asteroid it wouldn't be anywhere close to impacting the Earth. The size of asteroid they intend to capture and the type of orbit in which they intend to place it will be stable enough that no one will have to adjust its course for decades.
The Keck team seems to have thought of everything, which is probably why NASA is actually considering the plan. It would be weird, though, to suddenly have a second Moon, even if it’s a tiny one we can barely see.