Discovery astronauts packed up on Friday and got ready to leave the International Space Station as the first shuttle visit to the outpost since 2002 - and likely the last for a while - neared its end.
NASA earlier declared the shuttle safe to return home, clearing the way for what is the first step toward Discovery's planned landing on Monday in Florida.
The Discovery crew was to say goodbye to station crew members Sergey Krikalev and John Phillips late on Friday, close the hatch and get ready to undock early on Saturday.
The astronauts busily stowed gear and finished loading the spacecraft and an Italian-built cargo unit packed with tons of trash and other items that have piled up on the station over the past 2-1/2 years.
It may be the last shuttle visit to the space station for some time because NASA has grounded the shuttle fleet until it fixes the flying debris problem that destroyed Columbia in 2003 and resurfaced at Discovery's launch on July 26, reports Reuters.
According to CBS, Friday’s activity came a day after NASA gave the all-clear for Discovery to return to Earth, concluding that there was no need to send the astronauts out on another spacewalk to repair a torn thermal blanket near a cockpit window.
The damaged 20-inch-long, 4-inch-wide insulation blanket just below commander Eileen Collins' cockpit window was the only remaining question mark about the shuttle's condition prior to re-entry and landing early Monday morning, CBS News Space Consultant Bill Harwood reports.
Mission managers could not guarantee that a piece of the blanket wouldn't rip and slam into the spacecraft during re-entry, but said the chances were slim.
“We have assessed the risk to the very best of our engineering knowledge and we believe that it is remote, small, whatever adjective you want to put with that,” deputy shuttle program manager Wayne Hale said. “and the remedy that might be called for to try to make this better would be worse.”
NASA managers decided that a fourth spacewalk wasn't necessary to fix a damaged piece of a thermal insulation blanket below the commander's window on the shuttle. Engineers spent two days analyzing images of the damage and conducting wind-tunnel tests to assess whether the blanket may tear off during re-entry, risking further damage to other parts of the shuttle.
Discovery's crew during preparations for the mission practiced experimental repair methods developed in response to recommendations from an independent board that investigated the destruction of the shuttle Columbia. A piece of insulating foam struck Columbia during launch, causing a hole that filled with atmospheric gases on the craft's return to Earth in February 2003, killing all seven astronauts on board.
Mission specialist Steve Robinson made use of that practice this week, becoming the first astronaut to make repairs to the shuttle's heat shield, which protects the spacecraft during re- entry. Robinson two days ago removed two bits of “gap-filler” fabric that were protruding from between the tiles that make up the heat shield, informs Bloomberg.