The use the robotic arm and sensors attached to it to run another inspection before the scheduled spacewalk begins Friday morning.

NASA has been especially diligent about studying the heat shields since the apart upon re-entry on Feb. 1, 2003. According to NASA, an investigation found that the disaster was caused by a hole in the heat-resistant panels that protected the wing from the high temperatures of re-entry. The hole allowed superheated air into the wing, which was destroyed, sending the shuttle spinning out of control before it broke apart.

Atlantis blasted off from the Kennedy Space Center on Monday afternoon. The crew is on an 11-day mission to repair and upgrade the Hubble Space Telescope.