At this point, doubtless everyone has heard about contact with the Space Shuttle being lost this morning about 8am CST.
The presumption is that the Shuttle broke up on reentry and that all hands were lost.
Personally, I have very vivid memories of the Challenger accident back in 1986. I was a freshman at the University of Illinois and was working at NCSA, which housed a large group of astrophysicists. That morning, when I arrived at the office, I was transfixed by the video and shocked by the tragedy both from a human perspective and from the perspective of one who believes that the future of the human race is tightly coupled with the exploration of space.
After 17 years, I find myself once again staring at video of unexpected contrails, with sympathy in my heart for those personally touched by this tragedy and with great concern over the effect this could have on the future of space exploration.
Further news will be available through all media outlets and from NASA.