The space shuttle Discovery's mission to the international space station is being extended by a day, leaving time for a third spacewalk to test orbital repair techniques, NASA said Friday.
Mission managers approved the extension to a 13-day flight, as widely expected, after determining that the shuttle had enough power reserves to support the extra day.
Also on Friday, the combined shuttle and station crews started transferring thousands of pounds of cargo from Discovery's payload bay to the station — and took a closer look at potential trouble spots on the shuttle's underbelly.
At the beginning of their third full workday in space, Discovery's astronauts moved a huge cargo container, nicknamed Leonardo, onto the space station by robotic arm. Among the goodies awaiting the space station crew were a new stationary bicycle for exercise, an oxygen generator that will eventually allow the space station to support six inhabitants, a machine that cools the station’s cabin air and a lab freezer for scientific samples.
“Have fun putting a new room on the station today — the float-in closet, every home needs one,” flight controllers in Houston wrote the shuttle crew in their daily morning electronic message.
Unloading items 220 miles (350 kilometers) above Earth was even more difficult than moving into a house, since at least there’s gravity on the ground, Steve Lindsey, Discovery’s commander, said in downlinked interviews with reporters.
“It’s really kind of a challenge because you’re in zero-G ... you’ve got to go very, very slow because if you go fast, you kind of run into things and bump into other equipment,” Lindsey said. “It’s kind of an interesting choreography we have to go through.”
‘Areas of interest’
Astronauts also spent several hours focusing the cameras on six specific “areas of interest” on the shuttle that had been seen in earlier photographs. Engineers need more information about the heat shield to ensure there is no damage like the kind that doomed Columbia’s flight in 2003.
Mission managers agreed that three of the six areas posed little risk, said Steve Poulos, manager of the orbiter project office. He said two more areas have not been cleared but were unlikely to be an issue.
That left just one concern that cautious NASA managers said they could not discount yet: a piece of fabric filler protruding from the thermal tiles on the aft end of Discovery’s belly. The gap filler is material fitted between tiles to prevent them from rubbing against each other. Two pieces of gap filler had to be removed from Discovery’s belly during a spacewalk last year because of concerns they would cause problems during re-entry.
A similar operation would have to be conducted next week if NASA decided the gap filler had to be removed this time. Because the protruding filler is in a hard-to-reach area, spacewalkers would have to work on the end of the shuttle’s 100-foot (30-meter) robotic arm and boom extension — a technique that is to be tested for the first time during the mission's first spacewalk on Saturday.
Besides the filler, NASA was looking at a horseshoe-shaped white spot on the shuttle’s nose cap that engineers have described to the crew as resembling bird droppings — but not the same as white splotches found earlier on the wing. The concern was that the spot could be a hole in the thermal-protection system and need repair, but Poulos said the close-up photographs convinced him that it was not a divot.
Two areas of concern that engineers had not discounted, but Poulos said were unlikely to be a problem, were discolorations on Discovery’s right wing, including the area where it gets hottest during re-entry. If they need to be fixed, the crew already was slated to test a patch kit, he said.
Mission extension is ‘great news’
The chairman of Discovery's mission management team, John Shannon, told reporters that he would withhold judgment on repair operations until the experts had completed their analysis. He also confirmed the plan to extend the mission from 12 to 13 days.
Space station astronaut Jeff Williams told Associated Press Television News that the extension was “great news because it gives us a whole lot more capability and a little more bang for the buck, if you will, for this shuttle mission.”
The extension would leave enough time for the third spacewalk on July 12. Spacewalkers would practice a variety of techniques for detecting damage to the shuttle's tiles and protective panels, and fixing that damage if necessary.
The development of repair techniques may be key to the shuttle fleet's future: Columbia’s seven astronauts were killed during re-entry when fiery gases entered a breach in the shuttle’s wing. The breach was caused when foam debris from the external tank struck the wing shortly after liftoff.
This report includes information from The Associated Press and MSNBC.com.