The crews of Atlantis and the international space station greeted each other with hugs and handshakes Sunday after the space shuttle arrived at the orbiting outpost.
But amid the smiles and salutations, engineers in Houston 220 miles below started evaluating whether a peeled-back thermal blanket should be fixed by astronauts.
A decision likely will be made in the next day or two, and if the answer is to fix it, another decision will be made on whether it would be done during one of three scheduled spacewalks or during an extra, unplanned one.
Astronauts James Reilly and Danny Olivas planned to make the mission's first spacewalk on Monday to help attach a new 35,000-pound segment to the space station.
Engineers who had studied past damage to the blanket area, located on a pod of engines near the shuttle's tail, on other shuttle missions were uncomfortable with the safety margins of a piece of the blanket sticking out during re-entry into Earth's atmosphere when temperatures on the shuttle's heat shield can reach as high as 2,900 degree Fahrenheit during re-entry.
Temperatures at the blanket's location only reach 700 degrees to 1,000 degrees Fahrenheit.
"The concern is that if it sticks up, you get additional heating," said John Shannon, chairman of the mission management team.
Engineers were confident the loosened blanket was caused by aerodynamic forces during launch, not by being hit by a piece of debris during lift off.
"Since this wasn't an impact blow, we have high confidence that the structure beneath it is pristine," Shannon said.
The rest of the vehicle appeared to be in fine shape, NASA said. Sensors reported six hits on the wing during launch but engineers were not concerned about them.
Hatches between the two spacecraft opened about — 1/2 hours after the shuttle docked with the space station following leak checks.
"Atlantis arriving," U.S. space station resident Sunita Williams said after the traditional ringing of a bell.
Atlantis' astronauts floated into the space station's Destiny laboratory and hugged each of the station's residents, which besides Williams includes commander Fyodor Yurchikhin and cosmonaut Oleg Kotov.
After exchanging greetings and receiving a safety briefing from Yurchikhin, both crews resumed working.
Before reaching the space station, Atlantis commander Rick Sturckow told Yurchikhin that shuttle astronaut Clayton Anderson was ready to relieve Williams on the station.
"Are you sure Clay is onboard?" Yurchikhin said.
NASA enjoys meeting in space