Engineering teams will meet Friday to discuss the status of the work currently under way.Īfter Discovery's final flight, NASA plans to retire the shuttle - along with the rest of the agency's shuttle fleet - in 2011. In fact, you ran the risk of introducing errors because you couldn't thoroughly test them."ĭiscovery's STS-133 mission managers are evaluating the data to determine the schedule of repairs and the next possible launch opportunity for the orbiter. "At the time, we wouldn't have gained confidence in the system by switching them out. But, now that they have some extra time, the engineers can go through a full series of tests," Beutel said. "It cleaned itself out, basically – it never showed up again. The hiccup was thought to have been caused by transient contamination, and after 24 hours of tests and evaluations, the problem did not return. Shuttle technicians encountered an electrical glitch with one of the orbiter's backup engine controllers on Nov. As a result, engineering teams have opted to remove and replace a cockpit panel circuit breaker that caused a separate launch delay early last week. With the Discovery's launch delayed, NASA teams now have the ability to perform more thorough examinations of the shuttle and its hardware components. NASA officials stressed, however, that the cracked area is clearly visible during pre-launch inspections, and would have been detected by the final inspection team before liftoff. But while the foam was firmly attached to the damaged structure, launching the vehicle in that configuration could present potential hazards, NASA officials said. Previously, these types of cracks were addressed during the external tank production phase at NASA's Michoud Assembly Facility in New Orleans, La., where space shuttle fuel tanks are built.Įngineers determined that cracks in a single stringer would still leave the intertank with enough structural capability for launch and ascent. But these repairs have never before been executed at the launch pad. Shuttle technicians have repaired similar cracks on external tanks by removing the fractured aluminum and replacing it with a twice-as-thick stringer section, before replacing the foam. It's a known failure method."Įngineers are now evaluating images of the cracks to determine the best repair options that can be performed with Discovery remaining at her seaside launch pad at Kennedy Space Center. "They understand the stresses that go on at cryogenic temperature levels while loading the tank. "Even though the foam didn't come off, the crack underneath propagated up, so the cracks in stringer led to the crack in the foam above it," Beutel explained. The cracks in the stringer likely pushed the metal outward to sufficiently dislocate the foam, NASA officials said. The fractures were found underneath the area of cracked foam, and early analysis suggests they were the root cause of the foam damage. The two 9-inch (23-cm) cracks were located at a site called the "stringer," which is an aluminum strip that provides structural integrity to a part of the fuel tank known as the intertank - the partition between the liquid oxygen and liquid hydrogen tanks. 10) on a section of the tank's aluminum skin. While removing the cracked foam layer that covers the tank, two new fractures were found yesterday (Nov. 12), Beutel said.Įngineers also removed damaged foam insulation on Discovery's external tank that cracked during initial loading operations for the shuttle's most recent launch attempt on Nov. This is very different."īased on early evaluations, the team should be ready to install a new flight seal and umbilical carrier plate tomorrow (Nov. "Last year the issue was a slight misalignment of the whole carrier plate. "They found that the flight seal was not properly aligned when they opened up the GUCP," Beutel told. This could account for why the leak cropped up earlier in the tanking process, and leaked significantly greater amounts of hydrogen, than the two previous events, NASA spokesman Allard Beutel said. Both of these were caused by slight misalignments of the carrier plate itself, but this new leak was caused by a different issue - a misalignment of the flight seal inside the ground umbilical carrier plate. Similar leaks have occurred during launch preparations for two previous shuttle missions, both in 2009. Data collected from the initial inspections will be evaluated today. NASA technicians worked overnight to remove the component, and initial inspections were performed on the faulty seal and its corresponding connector before they were sent to labs for more thorough examinations.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |