[Note: I am live tweeting the Hubble servicing mission on my @BANews Twitter feed. Sunday is when they fix STIS, and I'll be hanging on the NASA video feed for every second of it!]
The Lunar Reconnaissance Orbiter, NASA's first step in (what better be) a return to the Moon, has been delayed from June 2 to June 17. It'll be launched on an Atlas with a Centaur upper stage rocket. After LRO is deployed and sent lunarward, the Centaur will be aimed at the Moon as well, but on a collision course. It'll slam into the Moon so that LRO can observe the impact and learn about the lunar surface (and presumably what's beneath it as well). Since a Centaur has never been used in this way before, NASA is delaying the launch so they make sure some valve issues are understood and under control. Delaying a lunar shot isn't that bad, since the Moon only goes around the Earth. That makes timing easier; it's aiming at other planets that's harder to delay since their relative positions around the Sun -- and therefore their velocities -- can change by so much with time. This two week delay for LRO is frustrating but not a huge problem, unless you're impatient like me when it comes to launches.
