No more foam: Shuttle Columbia was doomed when a piece of foam broke off, hit the wing of the shuttle and damaged its heat shield tiles during takeoff in January 2003. NASA wanted to get rid of the foam, which was used at the three places where the shuttle attaches to the fuel tank. The foam was important because it helped prevent the buildup of ice. (Flying ice could do as much damage as flying foam.) So NASA designed heaters (shown in green) to replace the foam.
Taking the wings' temperature: Multiple sensors placed behind the edge of Columbia's wings can record 20,000 temperature readings a second. Changes in the temperature along the wing could indicate problems such as Columbia had. Should the sensors detect a temperature spike along a wing, astronauts would know what part of the wing to fix.
Lots and lots of pictures: NASA has added nine camera sites (right) around Florida to get as many pictures of the liftoff as possible. Digital cameras also have been added to the shuttle, booster rockets and fuel tank. (Part of the problem in 2003 was NASA didn't have enough images to see how badly Columbia was damaged.) A camera on a specially designed "arm" (above) can take detailed pictures of heat shield tiles on Discovery's wings and belly.