NASA has already delivered an early version of its Asteroid Redirect Mission (ARM) designed to protect a planet from catastrophic impacts However, the planet being protected isn't Earth - ARM has been developed initially for Kerbin.
The Kerbal Space Program (KSP) is occupies an interesting niche between game and simulation. in which you create your own space program, starting with building your own rocket. As we reported in February it has attracted a large following, including engineers at NASA who embarked on a joint venture with KSP to produce a Kerbal version of the mission to identify and track asteroids and change their trajectories.
This one-minute video from NASA gives an overview of some of the concepts of the Asteroid Redirect Mission including capturing an asteroid and robotically collecting a boulder from its surface.
Now see this has been incorporated into the Kerbal Space Program:
As well as adding asteroids and The Claw (or Advanced Grabbing Unit, AGA) to capture them, the updated version of KSP features new rocketry parts based on NASA's upcoming Space Launch System.
So by collaborating with NASA the Kerbal version of the Asteroid Redirect Mission is true to its real-life counterpart (although ahead of it by perhaps more than a decade) as well as being fun and educational.
Meanwhile NASA's Asteroid Grand Challenge , which is looking for better algorithms for detecting asteroids, is continuing on TopCoder, giving developers a chance to win prizes as well as making a contribution to planet Earth's Asteroid Redirect MIssion.