Shuttle may need a new fix
SPACE CENTER, Houston – Spacewalking repairman Stephen Robinson was barely back inside Discovery and out of his spacesuit Wednesday when Mission Control called: What would he think about going out again to take care of another trouble spot?
NASA said it may order a fourth spacewalk, on Friday, to repair a torn thermal blanket beneath a cockpit window.
The news came moments after Robinson pulled off the first-ever repair of a shuttle’s thermal shield in space. Using his gloved right hand, he gently plucked out two potentially dangerous strips of filler material protruding from Discovery’s belly.
His success drew a big sigh of relief from NASA, which feared that the ceramic-fiber cloth might cause the shuttle to overheat during its descent through the atmosphere and lead to another Columbia-type disaster. At the same time, the space agency feared that the repair itself could cause more damage.
There was no immediate word from the exhausted but exhilarated Robinson on how he felt about going out on another spacewalk to deal with the thermal blanket.
Engineers are concerned that a 20-inch section of the blanket could rip away during re-entry, whip backward and slam into the shuttle, perhaps causing grave damage. They expect to know by this evening whether the danger is real and whether any blanket trimming is required.
During Wednesday’s repair job, Robinson never had to pull out his forceps or his makeshift hacksaw, which he took along just in case the filler material was stuck between the thermal tiles and he needed to employ more force. But he had to be careful not to bump into the shuttle’s fragile thermal tiles and make things worse.
Standing on the end of the international space station’s 58-foot robot arm, he tugged out the first piece as the two linked spacecraft passed over Massachusetts. By the time he had pulled out the next fabric strip 10 minutes later, he had crossed the Atlantic and was zooming over the French coast.
Robinson, a 49-year-old mechanical engineer and musician, became the first person to venture beneath an orbiting shuttle.
Robinson described what he was seeing and doing the entire time, so his colleagues would know he was safe.
“I’m pulling. It’s coming out very easily,” Robinson called. “The offending gap filler has been removed.”
The second piece slid out even more easily, with just a gentle tug of Robinson’s right thumb and index finger.
The mood aboard Discovery improved dramatically. Space station flight director Mark Ferring said he could hear “a palpable change in the tone” of the astronauts’ voices.
During the six-hour spacewalk, Robinson and Noguchi also installed a massive toolbox filled with spare parts on the space station.
NASA had spent four days analyzing the potential threat of the so-called thermal tile gap fillers and what to do about them.
Officials insisted it was absolutely safe to simply remove the fillers. The material’s primary purpose in those two spots was to prevent the shuttle’s ceramic thermal tiles from rubbing against each other and chipping during liftoff.
Teams of engineers and thermodynamic experts were also studying the torn, crumpled blanket beneath the commander’s side window.
The blanket is covered with a quiltlike fabric and stuffed like a pillow, and serves as insulation. It was apparently ripped by debris during the July 26 liftoff, the first shuttle flight since Columbia disintegrated on re-entry 21/2 years ago.
Hill said that in deciding whether to fix the blanket, NASA has to consider the possibility that a spacewalker could accidentally cause more damage and “make a bad situation worse.”
He said he believes the need for such a spacewalk is low, but said further analysis and tests will determine whether the shuttle is safe to return to Earth as is on Monday.