The space shuttle isn't the only launch that's had problems. The lift-off of experimental rockets from NASA's Wallops Flight Facility on Virginia's Eastern Shore has been delayed twice this week -- by bad weather.
NASA hopes to get the rockets up today --sometime between 9:30 a.m. and 1 p.m. But if not, they already have backup launch days set through July 23.
The rockets are part of a project to study neutral and charged particles in the ionosphere where communications and global-positioning satellites send their signals.