Astronauts test heat shield patch
2008-03-21 12:48
Houston - A pair of astronauts ended a spacewalk late on Thursday in which they tested a repair procedure for the heat shields on the space shuttle fleet - a technique Nasa hopes it never needs to use.
"I think it went really, really well," astronaut Rick
Linnehan, who was overseeing the spacewalk from inside the
shuttle Endeavour, radioed to spacewalkers Mike Foreman and
Robert Behnken after they finished the testing.
During the over six-hour outing the pair also replaced a
faulty circuit breaker and removed a thermal sock from the
station's new Canadian-built handyman robot, which was no
longer needed since it now has power from the station.
The heat shield test - part of a strategy to improve
shuttle safety - was the highlight of the fourth of five
spacewalks scheduled during Endeavour's busy 12-day repair and
construction visit to the International Space Station.
Columbia tragedy
Since the shuttle Columbia's demise five years ago due to
heat shield failure, Nasa has devised damage prevention and
repair procedures to give future shuttle crews a better chance
of surviving a similar accident.
Columbia's seven astronauts were killed as it broke apart
during its return to Earth for landing.
Using a tool that is like a high-tech caulk-gun, the
spacewalkers filled gouged tiles with a gooey gel. Some tiles
were intentionally damaged while others were unintentionally
broken during previous space flights.
"Mr Goo, you're in control today," Linnehan said as the
spacewalkers set up equipment for the tile repair tests.
Engineers are concerned to see if the goo will bubble up
inside, creating a lip around a repair that could trigger
excessive heating as the shuttle plunges through the atmosphere
on its way back to Earth.
The patched tiles will be packed up on the shuttle and
returned to Earth for analysis.
Nasa wants to have the results before dispatching a shuttle
crew to work on the Hubble Space Telescope later this year, as
the space station will be too far away to shelter the crew if
their ship is too damaged to return home.