The Gamma-ray Large Area Space Telescope, a satellite observatory designed to -- guess what? -- measure gamma rays, just launched on a Delta II rocket from Cape Canaveral. There were a few last-minute radar issues, but things seem to have ultimately gone off without a hitch. There is a launch blog here (naturally), and Phil Plait has been covering the mission in detail; there was a nice article in symmetry, and they also have a live blog. "Vehicle performance continues to look nominal..." You have to love scientists.
GLAST will be doing a variety of cool things, but there is one goal that stands out as uniquely exciting for physicists: it will be searching for dark-matter annihilations. If the dark matter consists of weakly interacting massive particles, they can come together and annihilate into a cascade of lighter particles. (Image from Sky & Telescope.) Among the particles produced are very ...