One of the numbered thermal tiles used on the first space shuttle Columbia hangs on display in Buliding 3, which houses the Teague Auditorium, the location where all news briefings are held at the Johnson Space Center in Houston, Tuesday, Feb. 4, 2003. The investigation into what caused Columbia to fall to pieces is leading NASA back to two things that have worried engineers almost from Day One of the shuttle program: foam and tiles. (AP Photo/Charles Rex Arbogast)Click to enlarge.
