The Planetary Society is hosting a contest allowing people from around the world design a mission to rendevous with and "tag" a Near-Earth asteroid that is scheduled to come dangerously close to our world in 2029, and again in 2036.
The asteroid Apophis (previously known as 2004 MN) is a 300-meter wide rock that orbits our sun and is currently millions of kilometers away. However, in 2029, this asteroid will come so close to the Earth that it will be visible from the ground and will be closer to the atmosphere than some of our satellites.
There is a very small chance that Apophis will hit the planet in 2029 (only a 1 in 45,000 chance), but some believe that it may fall into a 400-meter wide gravitational window that would send it around the sun, then smack into the planet on the next pass in 2036. This, of course, would be a bad thing. The resulting death and destruction on a global scale would be almost equivalent to what killed off the dinosaurs, and worse than that, my house (which should be fully paid off by then) will have a less than 50% chance of surviving the resulting destruction ... regardless of where the impact takes place.
Seriously, though ... this would be a bad thing.
So, in an effort to collect more data and determine what can be done about the asteroid should it become an Earth-bound object, the Planetary Society is offering a prize of $50,000 to the first engineering team that can design a space vehicle that will rendezvous with Apophos and send some telemetry and other data back to scientists here on Terra-firma. At least a hundred teams have already submitted their letters of intent, and the UK-based space firm EADS Astrium is busy at work developing a vehicle they're calling Apex, which would meet the asteroid in 2014.
I'm really looking forward to what possible solutions will be created for this. The technologies and methods developed here can be used to maintain absolute tracking of hundreds of other Near-Earth Objects that intersect our orbit every year. Because the goal of this project is not to develop a machine that will do anything to the asteroid itself, I would think the space craft could be relatively small. If we could develop units the size of the Mars Rovers (though immobile), it could be possible to launch a rocket with a dozen or so of these devices strapped on. Then, once in orbit, the tracking tags could be released and shot towards their intended targets. This would reduce one of the most prohibitive aspects of extra-planetary vehicles (being the actual escape from Earth) and could be cheap enough that every nation could work towards supplying a certain amount.
Of course, since we would be sending a machine towards a rock in space, I wonder how much it would cost to include some basic equipment to determine the asteroid's composition. If we had fifty years to do something about a potential collision, and the asteroid held a reasonable quantity of an ore of value, perhaps the best way to handle the matter would be to send an army of mining drones to rip the rock to pieces and refine just the ores. From there, we could devise a way to capture the ores safely and put them to use on either the Earth or our Moon. The remaining chunks of rock would have been demolished enough by the robots that our atmosphere could easily handle anything coming too close.
Ah, science fiction ... you make things sound sooooo easy :P