The space shuttle Columbia, on descent for landing in Florida, has apparently broken up over Texas and all contact was lost. NASA has declared an emergency. Debris has been reported landing in Texas, and NASA is warning people to stay away from anything that may be shuttle related due the the extreme toxic nature of some of the propellants. See CNN for details. President Bush has said it is “highly unlikely” it is any act of terrorism. Note that the descent phase is probably just as dangerous as ascent.