The Asteroid Redirect Mission is the stuff of science fiction, or at least it would be if NASA wasn't actually planning on doing it.
Put simply, NASA plans to send an autonomous spacecraft to an asteroid, remove a large chunk of it and then ferry it back into orbit orbit around the Moon, at which point a manned Orion mission will then study the rock.
Incredibly this is actually the scaled down version of the original plan which was to commandeer the entire asteroid and bring that back into orbit around the Moon.
The ARM mission is as much about education as it is training for Mars. It'll be one of the first major manned missions that extends beyond Earth's orbit and will be a pivotal test for the Orion spacecraft that would eventually take astronauts to the red planet.
It'll also be the testbed for a number of new technologies including the Solar Electric Propulsion system that'll be making its debut on the ARM robotic spacecraft.
This isn't going to be a quick job unfortunately, the robot will need six years to move the asteroid mass into orbit around the Moon. Then in 2020 NASA will launch its first Orion mission using the new Space Launch System rocket - the most powerful rocket NASA has ever built.
Once at the asteroid boulder the team of two will collect samples and conduct space walk training using the new deep space suits that are currently being designed.
NASA hopes that ARM will be a truly multi-role mission, not only will astronomers be able to study samples but it's a key opportunity for the US government to test out its asteroid defence protocols.