http://www.newscientistspace.com/article/dn9511-nasa-studies-three-areas-of-concern-on-shuttle.html
NASA studies three areas of concern on shuttle NASA officials were looking closely at three areas of the space shuttle Discovery's heat shield on Saturday to see if they posed a true threat to the spaceship. On Friday, Discovery pilot Mark Kelly and mission specialists Lisa Nowak and Stephanie Wilson used a digital camera on the end of a boom attached to the shuttle's robotic arm to take close-up still pictures of six areas of concern on the orbiter. By Friday afternoon, shuttle managers determined that three of those areas posed essentially no threat to the mission. But they are still investigating three areas – a gap filler sticking out from between tiles near a door towards the rear of the spacecraft and two reinforced carbon panels on the leading edge of the wing. Gap fillers are pieces of silica-coated fabric used both to keep the heat shield tiles from rattling against one another during launch and to prevent hot air from reaching the skin of the orbiter during atmospheric re-entry. Weakest part Two gap fillers were found sticking out from between tiles during Discovery's last mission in July 2005 and had to be removed during a spacewalk. The concern was that these protruding pieces of fabric could cause turbulence below the orbiter on atmospheric re-entry, potentially heating it up beyond its design parameters. In a worst-case scenario, that might cause a Columbia-like disaster. So before the current mission launched on 4 July, technicians replaced more than 5000 gap fillers on the most critical areas of the orbiter. The gap fillers protruding now had not been replaced before the mission. The one near the door, which was installed in 1982, could pose a threat because of its height. The initial analysis of the images suggests it could be sticking out by at least 2.5 centimetres (1 inch). NASA is especially concerned about this area because it is near the door where propellant from the external fuel tank flows into the orbiter during launch. Doors and the seals around them represent some of the weakest parts of the orbiter, and any damage to those areas could create a pathway for super-heated air to enter the orbiter during atmospheric re-entry, says orbiter project manager Steve Poulos. But overall, Poulos says he was pleased with the condition of Discovery. "There is nothing that jumps out in terms of tile damage like we saw on the last flight," Poulos says. On that flight, close inspections found minor "dings" from falling foam during launch, but fortunately nothing that would endanger the astronauts during atmospheric re-entry. Fantastic view Although nothing is leaping out as a major problem with the heat shield, shuttle managers have not officially ruled out that possibility and whether they might need to undertake a spacewalk under the orbiter to inspect or repair the heat shield. Analysts are still looking at images that were taken by the astronauts with the shuttle's robot arm before the shuttle docked to the International Space Station on Thursday. "I am completely withholding judgment until the analysts come back," says deputy shuttle manager John Shannon. On Thursday, the two ISS astronauts took pictures of Discovery's heat shield as it did a back flip beneath the station to look for any damage on the orbiter. "A fantastic view to see such a grand vehicle outside our window," says ISS flight engineer Jeff Williams. "We completed that as planned. We saw nothing out of the ordinary, nothing of interest." Astronauts Piers Sellers and Mike Fossum began the first spacewalk of their mission at 0917 EDT (1317 GMT) on Saturday. During their 6.5-hour jaunt outside, they will test whether a 15-metre extension to the shuttle robotic arm would be stable enough to use as a work platform to repair a damaged heat shield (see Shuttle astronauts will wobble on robotic arm). They will also begin the process of replacing part of the Mobile Transporter, a rail car that allows the ISS robotic arm to move the length of the station's backbone-like truss (see Astronauts to do 'heavy' lifting on spacewalks). Reply with a "Thank you" if you liked this post. _____________________________ MEDIANEWS mailing list medianews@twiar.org To unsubscribe send an email to: [EMAIL PROTECTED]
