Space Shuttle Discovery Lands After Landmark Flight

This story was updated at 6:29 p.m. EDT.

HOUSTON - Space shuttle Discovery returned to Earth on Saturday, ending a successful 13-day mission that completed the International Space Station?s backbone and brought the outpost to full power and symmetry with the addition of two final solar array wings.

Discovery?s STS-119 commander Lee Archambault piloted NASA?s oldest orbiter to a safe touchdown at 3:13:17 p.m. EDT (1913:17 GMT) on Runway 15 at the Kennedy Space Center?s Shuttle Landing Facility in Cape Canaveral, Florida. The return was delayed by one orbit to provide time for clouds and gusting crosswinds to clear from the vicinity of the landing strip.

"Welcome home Discovery after a great mission to bring the International Space Station to full power," astronaut George Zamka told the crew from Mission Control here.

"Thank you very much, it is good to be back home," Archambault replied.

Returning with Archambault and Antonelli on Discovery were mission specialist John Phillips, lead spacewalker Steven Swanson, educator astronauts Joseph Acaba and Richard Arnold II, and Sandra Magnus, who was returning from the space station after 134 days in orbit. She traded places with Japan?s first long-duration crew member, Koichi Wakata, who launched with to the station with the STS-119 crew. 

?I'm looking forward to being home and seeing everyone today, hopefully," Magnus said early Saturday.

Space station at full power

The STS-119 crew launched on March 15, bringing the 30,000-pound (13,607-kg) Starboard 6, or S6, truss segment, a 45-foot (13.7-meter) long girder tipped with two 115-foot (35-meter) solar wings to the space station.

Swanson and Arnold bolted the truss segment to its adjoining piece on the right edge of the station during the mission?s first spacewalk, completing the station?s 356-foot (108-meter) backbone. Two subsequent spacewalks by Swanson, Arnold and Acaba worked on configuring the outpost?s outside equipment for future shuttle missions, as well as the arrival of Japan?s first unmanned cargo craft, the HTV.

With the S6 truss installed, the astronauts deployed the segment?s solar arrays, nearly doubling the available power to the station. With all eight wings extended, the station - now symmetrical in appearance - generates enough electricity to power 42 average-size homes. It is now about 81 percent complete.

?This is really an amazing time and an amazing mission,? said NASA space operations chief William Gerstenmaier after Discovery landed.

Gerstenmaier said he was awestruck at the first images of the space station with its complete power grid, which astronauts beamed down Wednesday after undocking.

?That?s probably the most amazing image that you can ever imagine,? he said.

Discovery also delivered a replacement distillation unit for the station?s malfunctioning urine processing assembly, part of a water recovery system that will be used to recycle the crew?s waste into potable water. After some initial trouble that required the replacement of filters, space station commander Michael Fincke was able to get the recycler to process urine, and samples of the resulting water were brought back to Earth on Discovery to be tested.

The addition of the solar arrays and the installation of the water recovery system was necessary before the space station could increase its crew compliment from three to six residents.

With both accomplished, the orbiting lab was ready for the arrival of the Russian Soyuz TMA-14 spacecraft at 9:06 a.m. EDT (1306 GMT) Saturday, just a few hours before Discovery landed, delivering the station?s next increment crew and American billionaire Charles Simonyi, the world?s first repeat space tourist. The Expedition 19 astronauts will continue to ready the outpost before helping to form the first six-person crew in May.

Tripping the boundary

While Discovery?s heat shield received a clean bill of health with respect to launch and orbital debris, mission managers were still expecting the shuttle to ?trip the boundary layer? early as a part of an experiment designed to improve engineers? understanding of how spacecraft re-enter the atmosphere.

Engineers added a slight protuberance, or ?speed bump,? to one of the thousands of heat shield tile on the spacecraft?s underbelly to disturb the hypersonic airflow surrounding the orbiter, creating turbulence that, in turn, should result in increased heating downstream of the specially-fabricated tile?s position near the rear of the left wing. The bump posed no risk to the shuttle or its crew, mission managers said.

?Obviously the shuttle is one of a kind, it?s a winged vehicle flying at these very high Mach numbers, and that boundary layer transition [test] will allow us to collect some very good heating data,? entry flight director Richard Jones Friday here at the Johnson Space Center.

The bump should have its effect as the orbiter travel Mach 15, or 15 times the speed of sound. In addition to sensors installed under and around the tile, a U.S. Navy aircraft will fly under Discovery?s path, recording infrared imagery of the orbiter?s belly as it trips the boundary.

The results of this test may help NASA create a better heat shield for its next generation crew exploration vehicle, Orion, being designed to take astronauts to and from the space station, as well as return humans to the Moon.

Other than that intentional protuberance, Jones said that the shuttle was safe for reentry. ?This mission has just been exceptionally clean, Discovery and her crew have been performing just flawlessly,? he commented.

Discovery?s mission marked the 125th for NASA?s space shuttle program and the 36th flown by the orbiter. NASA plans to launch up to eight more shuttle missions by 2010 to complete station construction and one more - set to launch May 12 - to overhaul the Hubble Space Telescope one last time.

The mission was also the 100th flight since the loss of space shuttle Challenger in January 1986, which was highlighted by the delivery of the 100th bouquet of flowers to Mission Control by the Shelton family of Texas. Space enthusiasts Mark, Terry and their daughter MacKenzie Shelton have been sending the roses - one for each space shuttle crew member and a white rose for those lost in flight - for every shuttle flight over the last 21 years.

?They represent many families out there that are looking at NASA and are appreciative of the work that we hope we are doing for everyone out there,? said Jones.  

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