After successfully docking with the International Space Station, the Discovery astronauts interrupted their scheduled tasks to perform a brief inspection of heat shield panels on the shuttle's left wing leading edge.
The unscheduled inspection was prompted by the detection of a very minor impact on the shuttle wing early Tuesday morning and was a precautionary step done in order to avoid a time-consuming focused inspection on the fifth day of an already busy flight.
Sensors on the wing designed to detect vibrations from impacts reported the ding at about 5:30 a.m. EST (1030 GMT) this morning, while the seven STS-116 astronauts were still asleep.
During the inspection, mission specialists Joan Higginbotham and Sunita Williams used the station's 57-foot camera-equipped robotic arm to scan four reinforced carbon-carbon (RCC) panels on the shuttle's wing.
Preliminary analyses of the images reveal nothing of concern, said NASA deputy space shuttle manager John Shannon in a news briefing today.
"The team has looked and gone through and done their first pass on all of the wing leading-edge RCCs and the nose cap and has identified no issues," Shannon said. "It is a very rigorous process."
He added that the impact detected by the wing sensors was only about 0.12 gravity root mean square (GRMS), about 1/100th of what would normally generate concern.
It takes about a 10 GRMS impact to create a scuff on a heat shield tile, and a 20 GRMS collision to make a crack or hole.
Images shot by ISS crewmembers during Discovery's rotational pitch maneuver (RPM) before docking — during which the orbiter performs a 360-backflip — also revealed minor scuffs and discoloration on some of the tiles, particularly around the external tank (ET) umbilical cord doors on Discovery's port wing, but these are not expected to be of concern either, Shannon said.
Led by STS-116 commander Mark Polansky, the STS-116 crew will participate in three spacewalks over the next week to install a new $11 million Port 5 (P5) spacer segment to the ISS, switch on a thermal cooling system and rewire the orbital laboratory's electrical grid so it can draw power from a new set of solar panels arrays installed last month.
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