"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.