Another milestone for the human race occurred last week with barely a ripple of notice: the Messenger spacecraft began a series of flybys of the planet Mercury, the first since Mariner 10 back in 1974. Messenger sent 500 MB of photos and scientific data back to NASA after the first of many flybys, and in three years it will settle into orbit around the planet. You can see photos and get lots of other info at a slick and easily accessible website. If you talk about bang for the buck, these unmanned space missions are an unbelievable bargain.