Crew includes Twittering skipper, singer, ER doc

The astronauts headed to the international space station include a Twittering skipper, a classically trained musician who named her son after one of Columbia's fallen astronauts, and a former Navy SEAL who went into Afghanistan two weeks after the Sept. 11, 2001, terrorist attacks. Space shuttle Endeavour's motley crew of seven is scheduled to blast off Saturday. When they join the six residents