NASA regularly opens up challenges to foster development of new and exciting space technology, and it looks like it's come up with a particularly challenging one recently -- it's asking interested parties to develop a solar-powered "Night Rover" that can store up enough energy during the day to continue to work throughout the night. That's as opposed to the more recent crop of rovers that must do most of their work during the day, which NASA says forces them to pick and choose what tasks the rovers perform, thereby greatly reducing the chance for discoveries. It also notes that simply adding more batteries isn't an option, since every tiny weight increase significantly adds to the cost of sending something into space. Think you've got what it takes? There's a $1.5 million dollar prize in store for the winner.