Focused inspection of tile damage under way

Endeavour astronauts have begun an inspection of a damaged heat shield tile on the orbiter's underside.

The "focused" inspection began at 3:35 a.m., a bit late after trouble activating the sensor package at the end of a boom positioned beneath Endeavour.

The astronauts today used the International Space Station's robotic arm to attach the 50-foot boom to the shuttle's 50-foot arm.

The boom then swung below Endeavour's left wing so the boom was positioned about seven feet from the damaged area on the right side.

The damage was created when ice struck the tiles 70 seconds after liftoff. It is located between the right main landing gear door and the right rear external tank attach point door.

The gouge measures 3.22 inches by 2.49 inches, but the depth, estimated at 0.7 inches, is uncertain.

Images collected this morning by a digital camera and laser sensors on the end of the boom will give analysts in Houston a more accurate 3-D picture and better data for models that assess heating limits.

NASA does not believe the damage is serious enough to warrant repair, but is performing the focused inspection -- the fifth in 21 post-Columbia flights -- to be sure.

"The expectations are that this will be cleared," said NASA TV commentator Kyle Herring.

According to notes sent to the Endeavour crew, the Damage Assessment Team that analyzes heat shield images was split on the need for a focused inspection.

"The results varied depending on what assumptions were made, and although the DAT team was split if additional imagery was required (to help clear this damage site), the MMT agreed that it was prudent to perform the Focused Inspection to provide the actual dimensional data and incorporate into the analysis process," the notes read. Click here to see the complete Flight Day 6 Execute Package.

An answer is expected within 24 hours.

Click here for a NASA TV schedule with highlights of the activity planned today and for the rest of the 16-day mission.