Engineers weren't sure if stitching on the blanket came loose or if the blanket, covering a pod of engines near the shuttle's tail, was hit by debris during launch Friday evening at Kennedy Space Center. The peeling back of the blanket left a gap about 4 inches by 6 inches.
With the exception of that single thermal blanket, Atlantis looked to be in great shape after astronauts spent Saturday meticulously scanning its heat shield with a camera attached to the end of a robotic arm and boom to make sure there was no damage from launch like the kind that doomed Columbia in 2003.
"It's not a great deal of concern right now, but there's a lot of work to be done," John Shannon, chairman of the mission management team, said of the blanket. "Other than that, the vehicle is very clean."
Before Atlantis was to arrive at the space station, astronaut Danny Olivas was to take additional photographs from inside the shuttle of the area where the thermal blanket had peeled back. The images were to be sent to Mission Control for analysis.
Shuttle astronauts were awakened Sunday to the song "Riding the Sky," written by two Johnson Space Center employees and dedicated to Atlantis crew member Clayton Anderson, who is set to be the newest resident of the space station.
"We're looking forward to a great day and seeing our friends on the station," Anderson told Mission Control. By 9:30 a.m. EDT, the shuttle was about 336 miles away from the station.
NASA engineers want to study more photos of the torn blanket, particularly images that were taken by cameras attached to the solid rocket boosters that separated from Atlantis more than two minutes into flight and then dropped into the Atlantic Ocean. The boosters are recovered by ships after each launch, and mission managers could have the images by Monday.
Engineers also plan to study past shuttle flights.
Thermal blankets came unstitched during flights of Discovery in 2005 and 2006 without any problems, and thermal tiles were lost in the same area where the blanket is on Atlantis on two of the earliest shuttle flights.
The area does not get hotter than 1,000 degrees Fahrenheit during the shuttle's return to Earth, compared with other parts of the vehicle where temperatures can sizzle to 2,900 degrees Fahrenheit.
If engineers decide the blanket needs to be fixed, Atlantis' astronauts could trim if off, tuck it back into protective tiles or cover it with a plate held in place by adhesive goo during three planned spacewalks or an extra one added to the schedule.
After the Columbia disaster, a shuttle repair kit was included in all shuttle missions.
"We have wide spectrum of repair technologies," Shannon said.
During the 11-day mission, Atlantis will deliver to the station a new segment, which includes a third pair of solar arrays, and change out a U.S. representative at the space outpost. The new addition was expected to be attached to the station on Monday during the first spacewalk.
Atlantis was scheduled to dock with the space station at 3:38 p.m. EDT Sunday.
Before arriving at the space station, at about 600 feet beneath the outpost, Atlantis commander Rick Sturckow will maneuver Atlantis into a 360-degree flip so that the three residents at the space station can take photos of the shuttle's belly and transmit them to Houston for inspection for damage.
Soon after the space station and shuttle dock — as both travel 17,500 miles per hour — U.S. space station resident Sunita Williams and Anderson will trade out seatliners on the Russian emergency vehicle already attached to the station. The seatliner exchange marks the official replacement of Williams by Anderson as a resident of the space station.
Williams will return to Earth aboard Atlantis after more than six months in space.
"We're pretty much ready to go," Williams told Mission Control on Saturday. "We can't wait for our visitors."