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Shuttle, plus leak, set to land today
Look out Florida, here comes Discovery
The Space Shuttle Discovery is scheduled to land in Florida this afternoon, after completing an almost 13-day mission.
The Shuttle was cleared for launch late last week, the widely feared catastrophe having (fortunately) failed to occur. Even though a few pieces of foam did fall from the tank during the launch, a careful in-orbit inspection of the insulating tiles revealed no serious damage.
This means the astronauts can come back to Earth, rather than setting up residence in the International Space Station. It must be something of a relief, the ISS not being five star rated for comfort. Oxygen is sometimes an optional extra up there, after all.
The Shuttle detached from the ISS early on Saturday, and was given a final scan to check for damage. NASA described the undocking as "by-the-book".
Engineers were not worried about the Shuttle exploding during its launch, but were not sure that the problem of falling debris had been solved. The fear, of course, was that a piece of falling foam could once again damage the Shuttle's heat shield, as happened on the last flight Columbia made in 2003 before she broke up on re-entry with the loss of all on board.
Before the weekend only one question mark remained over Discovery's journey home; a small drop in pressure in one of the tanks that fuel the power units Discovery will use for braking and steering when she returns to Earth. The drop could have been caused either by leaking nitrogen, or hydrazine fuel.
Engineers were planning to test the unit yesterday, to see if the leak rate had changed. At the current rate, about six drops an hour, the leak is far too slow to cause a fire, even if it is leaking hydrazine. Once the test results are in, and once he is given the final all-clear, Discovery's Commander, Steve Lindsey, is scheduled to make the first de-orbit burn at 12:04pm, BST, when the mission will have lasted 12 days, 18 hours and 29 minutes.
All being well, the Shuttle should land at the Kennedy Space Centre in Florida. However, because of the uncertainty over the power unit, NASA also has emergency crews standing by at the Edwards Airforce base in California. ®