Barring any technical glitches, the Mars rover Curiosity is scheduled to land on the planet Mars sometime this weekend, and with the help of Microsoft and your Xbox Live account, you'll be able to be a part of it.
The special Mars Rover section in the Xbox 360 dashboard on the main page will let you join NASA TV live from Mission control during the final moments before the landing. You can also take quizzes and play the free Kinect Mars Rover simulator to earn a few achievements and add a little bit to your Gamerscore.
There's also some information on the engineering that went into building Curiosity. No doubt millions of dollars went into it too. Space exploration ain't cheap.
Find out more at Major Nelson's blog.