CAPE CANAVERAL, Fla. - Space shuttle Endeavour's astronauts inspected their ship for damage yesterday as NASA struggled to understand why a normally benign section of the fuel tank lost so much foam during lift-off.
The slow, tedious work unfolded for the seven astronauts aboard the shuttle as it rocketed toward the space station for linkup today.
Shuttle program manager John Shannon said the thin layer of foam insulation on the central area of the tank peeled away in approximately 6-inch strips as Endeavour blasted toward orbit Wednesday. The green primer on the metal skin of the tank was exposed in places.
Fortunately, he said, the shedding from this area - the so-called intertank connecting the hydrogen and oxygen reservoirs - occurred well past the critical two-minute mark in the flight and posed no danger to Endeavour.
"We have a bit of a mystery," Mr. Shannon said. "We're not worried about this flight, but we need to understand what was going on for the next flight."
Some foam broke off an adjoining area less than two minutes after lift-off, however, and hit the underside of Endeavour, where the right wing joins the fuselage. That left a series of dings in the thermal tiles.
Mr. Shannon said the damage looks to be less extensive than what occurred in practically the same place on the last flight.
In all likelihood, it's merely coating loss and considered minor, he said. More than a dozen pieces of foam came off the fuel tank during lift-off, at least two of which struck Endeavour.
"It was dramatic footage looking at it," Mr. Shannon said.
Throughout the afternoon yesterday, Endeavour's seven-member crew used a 100-foot laser-tipped boom to inspect their ship's heat shield, standard procedure since shuttle flights resumed after the Columbia accident. Columbia was destroyed during re-entry in 2003 because of a hole in its wing, left there by flyaway foam at lift-off.
But the boom could not reach everywhere, and NASA was going to rely on a complete photo survey of the shuttle, right before today's docking, to fill in the coverage gaps.
The space station residents will use zoom lenses to photograph every angle of the shuttle as it performs a somersault for the cameras.
Any additional damage should show up in those photos. It will take several days, however, to sift through the data.
Endeavour will remain docked at the space station for nearly two weeks.
During that time, the astronauts will install the third and final piece of the Japanese space station lab, a porch for outdoor experiments.
Five spacewalks are planned.