The logistics of landing rovers on Mars has been a point of endless fascination for me. NASA did it twice successfully (‘Spirit’ and ‘Opportunity’) before and now they’re going back again with ‘Curiosity’. This time the scale and complexity is more ambitious than it’s ever been. (And it was plenty ambitious before.)
I can’t think of anything more awe-inspiring and thrilling. Just trying to think about it will give you a head-ache, while simultaneously forcing you to question what it is that you’re doing with your life.