"The bottom line is there is large uncertainty because nobody
has a very good handle on the aerodynamics at [re-entry] altitudes
and at those speeds. Given that large degree of uncertainty, life
could be normal during entry or some bad things could
happen."
Source: Deputy Shuttle Program Manager Wayne Hale,
quoted by the AP, on justification for an unplanned, unrehearsed
EVA now scheduled for Wednesday. Discovery astronaut Stephen
Robinson will ride the orbiter's 58-foot robotic arm to a couple of
points underneath the shuttle, where he'll try to remove dangling
strips of filler material that could pose an overheating problem
during re-entry. Discovery is slated to return to Earth on
Monday.