After being docked together for 7 days, 22 hours and 34 minutes, the two space crafts parted at 3:53 p.m. EDT Wednesday. About a half an hour after the undocking, the shuttle and station began an hour-long process of taking pictures of each other. The images will be sent to NASA engineers on the ground who will study them as part of an effort to determine whether the craft suffered any damage to its thermal protection system, which protects the craft and its seven-person crew from blazingly high temperatures that come during reentry into the Earth's atmosphere.

The shuttle inspection continues Thursday morning when the crew will use Discovery's onboard robotic arm, , and an attached laser imager to inspect the external tiles that make up the heat shield, along with the shuttle's nose cone and the edges of the wings. Again, engineers on the ground will examine the images and data to check Discovery's thermal protection system.

Discovery is scheduled to land at 1:43 p.m. EDT Saturday at the Kennedy Space Center in Florida.

NASA has been especially diligent about studying the heat shields since the on 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 by it, sending the shuttle spinning out of control before it broke apart.

While the Canadarm 2 will be critical to inspecting the space shuttle on Thursday, it was also a key part of work that was done to the space station during this mission.