NASA is now more confident it can make minor in-flight repairs to a shuttle’s heat shield in orbit after the successfully testing of the repair techniques during the Wednesday spacewalk outside the Discovery.  According to Tony Ceccacci, lead shuttle flight director for the STS-121 mission, the preliminary results are positive. However, the repair technique will likely be limited to the types of repairs they performed.

During a seven-hour and 11-minute spacewalk, Piers Sellers and Michael Fossum tested application methods for a sticky, black material dubbed NOAX (non-oxide adhesive experimental). The space age material was formulated to fill in cracks and gouges to the carbon composite panels lining a shuttle’s nose cap or wing leading edges. Using spatulas and caulk gun-like tools, they applied NOAX to squares of reinforced carbon carbon used to protect the shuttle nose and wings from reentry temperatures. Then they spent three hours testing the technique by perching themselves on the space station’s robotic arm and a shuttle foot restraint to recreate the types of positions that would likely be used in the event of an actual repair.

Today’s spacewalk adds to the initial tests conducted during NASA’s STS-114 astronauts in July 2005 to determine the basic behavior of NOAX under actual flight conditions. “For STS-114, the conditions that we did the NOAX repair was more of a science project to see if we could throw it on the piece of RCC and determine what the results were,” Ceccacci said. “For 121, these guys went through a lot of work to determine exactly how you would repair [damage].”

Amidst all the work that the guys and gals of STS-121 have to do, they of course still have time to engage in some friendly and encouraging banter with the President of the United States. Nine crew members are responsible for transferring two tons of cargo (obsolete equipment, tools and other unnecessary items) between the shuttle Discovery and the International Space Station.

On the lighter side of things, President Bush was able to speak with the astronauts during a private ground-to-orbit telephone call. The President told the astronauts that he watched closely as STS-121 spacewalkers Piers Sellers and Michael Fossum worked outside their spacecraft, and invited the astronauts and their families to the White House. The President was also proud of the fact that Fossum is a graduate of Texas A & M University.

Discovery will return about 5,421 pounds (2,458 kilograms) of material to Earth, more than 4,000 pounds (1,814 kilograms) of which will be stowed in Leonardo during the descent, NASA has said. Among the first things to be unpacked were 82 containers of food and about 187 pounds (85 kilograms) of other provisions for the European Space Agency’s (ESA) astronaut Thomas Reiter, who joined station commander Pavel Vinogradov and flight engineer Jeffrey Williams as a member of the ISS Expedition 13 crew. Mr. Reiter obviously doesn't pack light (kidding)!

Also, astronauts Fossum and Sellers readied their U.S.-built spacesuits for one last spacewalk outside Discovery. They will spend roughly 6-7 hours working inside Discovery’s payload bay to test an experimental black, heat-resistant non-oxide adhesive (NOAX) material for use in repairing small cracks in the carbon composite panels that line the shuttle’s wings and nose. They will also test a new infrared camera by recording about 20 seconds of video of the carbon composite panels along Discovery’s wing edge. Let's wish these two brave men the best of luck as they spacewalk today!

The second of three spacewalks for the STS-121 mission was done last yesterday, July 10. To stow a spare cooling system pump and replace a broken cable reel for the ISS' Mobile Transporter, STS-121 spacewalkers Piers Sellers and Michael Fossum spent seven hours outside the station. The tasks will give NASA the green signal for a precisely choreographed series of 16 space shuttle missions (STS-121 included) that will complete the orbital laboratory and man it with six full-time astronauts.

August 28 will see the launch of NASA's first ISS construction mission since 2002 and it will deliver a pair of new solar panel wings and the massive truss mast to the orbital library. And to continue the orbital ISS construction effort, NASA also hopes to launch in December the STS-116 aboard Discovery.

Although the spacewalk was successful, it was not without complexities. Lead ISS flight director for NASA's STS-121 mission Rick LaBrode shared that the astronauts needed to work through stuck bolts, a stubborn spring that prevented initial attempts to install the new cable reel, and a lot of bumping - all of which made the task more complicated.

Tomas Gonzalez-Torres, lead spacewalker officer for the STS-121 mission however said that he wasn't worried at all; adding that he had a crew who can handle the job. "I couldn’t have asked for a better crew. These guys were fantastic," shares Gonzalez-Torres.

NASA mission controllers gave the go-signal for a third spacewalk and an extra day in space for the shuttle Discovery crew. “It’s a done deal,” according to lead shuttle flight director for Discovery’s STS-121 mission Tony Ceccacci. “We’re going to tell them we’ll step up to do a 13-day mission and we’ll plan accordingly.”

The extra day will give spacewalkers Piers Sellers and Michael Fossum a chance to test additional crack repair methods in the reinforced carbon carbon panels lining the shuttle wing leading edges. Ceccacci said the extra mission day will also give Discovery’s crew extra time for the cargo transfer operations and make heat shield repairs in case any damage is seen.

NASA set aside four hours today for the STS-121 crew to examine a gap filler jutting out near Discovery’s starboard external tank door, a gap filler along the forward section of the orbiter, a white spot that appears similar to bird droppings on the nose cap, two scuffs on a right wing RCC panel and a dark spot on another RCC panel on the same wing.

Sellers and Fossum are preparing for the first spacewalk to make repairs to the station’s railcar-like Mobile Transporter and test the stability of the orbital boom as a work platform.  The spacewalk starts at 9:13 a.m. EDT (1313 GMT) and can be viewed live on NASA TV.

NASA officials were still high on the success of Discovery even as they said much work remains ahead, including the evaluations of several pieces of foam debris dislodged from the orbiter's fuel tank during take off. A video camera on Discovery's external tank recorded at least three, possibly four, pieces of foam on the shuttle fuel tank falling off two minutes and 47 seconds into the launch.

According to  NASA space shuttle program manager Wayne Hale, "It could be an ice frost ramp, it could be something else. Both of those are interesting because they are after the time we are concerned about aerodynamic transport doing damage to shuttle tile." Shuttle officials said they expected to see foam loss during Discovery's launch and they are currently waiting the first report from analysts going through the images.

STS-121 mission specialist Michael Fossum and crewmate Stephanie Wilson conducted a photographic survey of Discovery's external tank separation and reported seeing what appeared to be a piece of cloth drifting between the shuttle and its discarded fuel tank. But NASA imagery analysts determined the object as ice drifting away from Discovery.

The upcoming Discovery mission set to launch early next month will have two of its shuttle astronauts performing a couple spacewalks and possibly a third one. The lucky future STS-121 spacewalking cowboys, Piers Sellers and Michael Fossum, are getting ready for at least two excursions outside Discovery for some space station repairs.

Their first tasks require them to safe a faulty guillotine-like device and then replace a cable reel on the space station’s Mobile Transporter (MT). In December last year, the MT’s interface umbilical assembly (IUA) accidentally fired its cable cutter severing primary power, data and video to the transporter.

They will also test whether NASA’s 50-foot extension of the spacecraft’s robotic arm (orbital boom) can be used as a work platform. The orbital boom is almost twice the length of Discovery’s robotic arm and the test would confrim if it can be used by astronauts to repair heat shield damage in occuring in otherwise inaccessible areas. The test will have the two spacewalkers bouncing on the boom over Discovery’s payload bay and then re-positioned near the station’s solid truss.

The orbital boom was developed after the Columbia accident to allow the space crew to scan their heat shield and determine their vehicle’s condition. Its orbiter boom sensor system (OBSS) cameras and laser-ranging scanners can search for blemishes or breaches on heat-resistant tiles and panels.

During their second venture outside, Sellers and Fossum will replace the transporter’s Trailing Umbilical System (TUS) which provides power and data to the MT. They will also install a spare pump for the station’s thermal control system located outside Quest airlock.

The third spacewalk, if time and shuttle power resources permit, will have Fossum and Sellers testing shuttle heat shield repair techniques. That space excursion would involve the two spacewalkers to apply a black, heat-resistant material called non-oxide adhesive experimental (NOAX) on cracks in the same type of reinforced carbon carbon panels lining Discovery’s wing leading edges.