"I didn't know it was going to be so hard (to say goodbye)," one of the Atlantis astronauts said before leaving the station for the last time.
Before leaving the neighborhood, Atlantis is flying around the space station on a photo-documentation tour, reports CBS News Space Consultant Bill Harwood.
The goal of the fly around is two-fold: To provide photo documentation of the station in its current state, which includes the new S1 solar array truss segment; and to give Melroy hands-on flying time with the shuttle.
The photo documentation is not mandatory, but "it's highly desirable," flight director Phil Engelauf said.
"It also serves to some degree as real, hands-on-the-stick piloting training time," he said. "We typically have the pilot fly the fly-around procedure. Usually, the commanders do the bulk of the critical flying during the missions and this gives the pilot the opportunity to get some real stick time before they eventually become commanders and are doing critical operations themselves."
During pilot Pamela Melroy's previous flight, the shuttle's KU-band radar system malfunctioned and the fly-around was called off.
"This is her second opportunity and we wanted to do what we could to make sure we got that opportunity for her, in addition to getting the photographic objectives as well," Engelauf said.
Atlantis docked with the station last Wednesday. The next day, during the first of three spacewalks by astronauts David Wolf and Piers Sellers, the new S1 truss segment was attached. Along with outfitting and activating the $390 million component, the shuttle crew also delivered 1,855 pounds of supplies, equipment and scientific hardware, along with more than 1,300 pounds of fresh water. Another 1,800 pounds of no-longer-needed equipment was transferred from the station to Atlantis for return to Earth.
Virtually all of the crew's objectives have been accomplished and the major components of the S1 truss successfully checked out.
"So far, the mission is going great, the crew is just doing an outstanding job and everything so far has met all of our expectations and in most cases, has exceeded those expectations," Engelauf said.
After the shuttle has left the vicinity of the space station, the crew will operate an experiment called SHIMMER and participate in round-robin media interviews beginning at 1:39 p.m.
"After we've undocked, we have the normal shuttle entry preparation activities, but in addition we have a secondary payload on this flight called SHIMMER," Engelauf said. "I confess, I even have to look up the name of this particular payload. It stands for 'Spatial Heterodyne Imager for Mesospheric Radicals.' It's an Air Force-sponsored payload that requires a little bit of out-the-window pointing for the shuttle to take some spectral images.
"This payload is essentially a demonstration of a new remote sensing technique using ultraviolet wavelengths in mapping hydroxyl in density distributions, which would be useful mapping the ozone layer and the chemical hydroxyl, which is largely responsible for the breakdown ozone."
CBS News Space Consultant William Harwood has covered America's space program full time for more than 15 years, focusing on space shuttle operations, planetary exploration and astronomy. Based at the Kennedy Space Center in Florida, Harwood provides up-to-the-minute space reports for CBS News and regularly contributes to Spaceflight Now and The Washington Post.