Endeavour Lands, Wrapping Up Record STS-123 Mission; Almost 16 Days In Space, 5 Spacewalks, 6.6 Million Miles

Space Shuttle Discovery Launch Delayed To 5:01 P.M. ET May 31 Because Weather Slowed External Tank Shipment By Barge From New Orleans-Michoud Facility To Kennedy Space Center

Engineers and technicians at Johnson Space Center are about to start tests that will show whether an emergency repair technique for damaged space shuttle protective heat tiles actually works.

Astronauts on the just-ended Space Shuttle Endeavour STS-123 Mission ventured out of the International Space Station (ISS) to make repairs to purposely damaged thermal tiles, similar to those that are mounted on each shuttle orbiter vehicle to protect it from the fierce heat of reentry.

The astronauts, maneuvering in the near-zero-gravity vacuum of space, squirted a liquid repair material nick-named "goop" into damaged areas on the test tiles.

Then they brought the tiles back to Earth on board Endeavour for the return trip to Earth, so that Johnson personnel can test the repairs.

Those test tiles will be subjected to the wicked heat and pressure that hit heat tiles on a shuttle orbiter vehicle as it returns to Earth at 12,000 miles an hour, to see whether the tile repairs successfully stand up to that harsh treatment.

If so, that will help to make the remaining space shuttle missions over the next two years safer for astronauts riding in the spaceships.

NASA has been concerned about shuttle orbiter vehicle heat tiles being damaged, ever since Space Shuttle Columbia in 2003 was destroyed because of tile damage. A chunk of foam insulation from the external fuel tank ripped loose during launch and ascent and smashed a hole in the heat tile on the leading edge of a wing on the orbiter vehicle. Later, as Columbia attempted to return to Earth, searing hot gases of reentry rushed into the wing, heating it to the point of structural failure. The ship and crew of seven were lost.

That tile repair experiment was just one part of a marathon mission for Endeavour and its crew.

Endeavour landed safely at Kennedy Space Center to bring down the curtain on the record STS-123 Mission to the space station, a voyage that included a daunting five spacewalks and myriad accomplishments.

The mission lasted 15 days, 18 hours, 11 minutes and 3 seconds, from the 2:28 a.m. ET launch in the dark from Kennedy on March 11, until the landing in the dark at Kennedy at 8:39 p.m. Wednesday, March 26.

To be precise, Endeavour recorded a main gear touchdown at 8:39:08 p.m., the nose gear touchdown at 8:39:17 p.m., and wheels stop at 8:40:41 p.m.

In all, the astronauts orbited the Earth 250 times at 17,500 miles an hour, covering 6.578 million miles.

It was the second shuttle mission completed this year, and four more shuttle missions remain on the flight manifest for 2008.

NASA must complete assembling the space station by a shuttle fleet retirement deadline of October 2010. That construction job requires shuttles, which alone have the size and power to haul huge and hugely heavy space station components into orbit.

Next, the busy NASA launch manifest for shuttle missions now has Space Shuttle Discovery slated for liftoff at 5:01 p.m. ET May 31 on the STS-124 Mission to the space station, providing another segment of the Japanese Kibo laboratory module, and a robotic arm for work in space outside the lab. The launch earlier was slated for May 25, but is being delayed because bad weather delayed shipment of the external fuel tank for Discovery from New Orleans to Kennedy Space Center. Also, NASA ordered the delay so that crew members wouldn’t have to work through the Memorial Day weekend to prepare the shuttle for flight.

The external fuel tank for Discovery, produced at Michoud Assembly Facility in New Orleans, arrived last week at Kennedy and was moved into the Vehicle Assembly Building where it will be mated with the Discovery orbiter vehicle and two solid rocket boosters.

That new external tank boasts some new-design titanium components that will permit NASA crew members to apply less foam insulation to it, thereby reducing the risk that foam will tear loose and damage the orbiter vehicle during launch.

As well, the new tank contains the earlier-devised corrections in the fuel sensor gauges data feed pass-through connector that carries fuel gauge readings from inside the tank, through to the outside and on to the orbiter vehicle. In the STS-122 Mission before Endeavour flew, faulty fuel gauge readings kept Space Shuttle Atlantis grounded for months before the problem was diagnosed and the fix was devised.

During the Endeavour STS-123 Mission, part of the Kibo Japanese laboratory was attached to the space station. Then the lab was opened, providing increased living space in the station. And a Japanese ground control center took over operating the lab.

Spacewalking astronauts also installed outside the space station a Canadian robot, Dextre, wrestling its arms into place. It will be able to perform many tasks outside the space station, meaning astronauts won’t have to perform as many spacewalks.