Space shuttle touches down safely in California
* 13:15 09 August 2005
* NewScientist.com news service
* Kelly Young, Johnson Space Center
Space shuttle Discovery touched down at Edwards Air Force Base, California at 0812 EDT (1212 GMT) on Tuesday, ending a 14-day mission to service the International Space Station.
The safe landing came as a huge relief as it was the first shuttle to land since Columbia disintegrated during re-entry to the Earth's atmosphere in February 2003.
Discovery's return had been delayed by 24 hours after rain and lightning at Kennedy Space Center in Florida had led NASA's entry flight director Leroy Cain to opt for an extra day in space. The weather for Tuesday’s landing in Florida was still not suitable, so Cain chose to end the mission in California. Rain can damage the heat shield tiles, though it does not endanger the landing.
During the 14-day mission, the crew travelled 9.3 million kilometres (5.8 million miles), transferred supplies the space station, tested heat shield repair kits and performed an unscheduled repair by plucking protruding gap fillers from the orbiter's belly.
So which moment was the tensest for the entry flight team? All of it, said Cain, before landing: “It’s pretty much about five minutes before we do the burn until wheel stop.”
Catch up with every twist and turn of the mission in our Return to Flight special report, including images, video, an interactive timeline and our exclusive "Instant expert" feature.
However, the landing in California will cost NASA a million dollars, as the then shuttle has to be transported back to Florida. It will ride piggyback atop a modified 747 jet for the cross-country flight.
The extra time needed might also delay the next mission by Atlantis in September, as Discovery has to be in Florida and ready to go as an emergency rescue vehicle.
The orbiter will cross the coast of California just north of Los Angeles to avoid the densely populated region. As it nears the landing strip, it will make a right-hand U-turn to line up with the runway. As it touches down, it is still travelling about 346 km/h (215 mph).
Super-heated gases
Columbia had a hole in its left wing caused by insulation foam that fell off the external tank during lift-off. Nine minutes after Columbia dipped into the outer boundary of the atmosphere, ground observers saw debris falling off the orbiter as it flew over California. Super-heated gases were entering the hole and destroying the craft.
After the Columbia accident, NASA completely revamped the space shuttle program, tackling engineering safety problems and how management decisions are made. The external tank was redesigned to limit the amount of foam and ice that could come off the tank and strike the orbiter.
But NASA still spotted four sizable pieces of foam coming off the external tank during Discovery’s launch. As a result, the agency grounded the remaining shuttles until they could determine the cause of the foam shedding.
The first ever detailed in-orbit inspection of Discovery’s heat shield did not find any similar damage on this mission. Video cameras and laser scans revealed scuffs and dings, but no holes.
During inspections, they did find two gap fillers protruding above the heat shield tiles on the orbiter’s belly. Astronaut Steve Robinson made an unprecedented spacewalk beneath the orbiter to pluck the gap fillers out to ensure they would not disturb the smooth air flow on re-entry.
