Space Shuttle Discovery Returns to Earth
15 July 2006
NASA administrator thanks International Space Station partners
Washington – Space shuttle Discovery and its crew are home after a 13-day, 8.5 million-kilometer trip to the International Space Station to test shuttle safety improvements, repair a space station rail car and produce high-resolution images of the shuttle during and after its July 4 launch.
Discovery (STS-121) commander Steve Lindsey, pilot Mark Kelly and mission specialists Mike Fossum, Piers Sellers, Lisa Nowak and Stephanie Wilson touched down at 9:14 a.m. EDT (1314 GMT) July 17 at NASA's Kennedy Space Center in Florida.
Lindsey and Kelly guided the ship as it descended from space at a speed of 27,239 kilometers per hour. During re-entry and landing, the orbiter is not powered by engines, Instead, it flies like a high-tech glider, relying first on its steering jets and then its aerosurfaces to control the airflow around it.
After landing, Lindsey and his crew did a traditional walk-around inspection of the shuttle.
"We had two major objectives on this flight,” Lindsey said from the runway. “The first one was to complete the return-to-flight test objectives that [STS-]114 started, and the second one was to get us ready ... for space station assembly and I think we accomplished both those objectives. We’re ready to go assemble [the] station and we’re ready to start flying shuttles on a regular basis.”
The flight also verified the safety of the biggest aerodynamic change to the external fuel tank in shuttle history.
The protuberance air load (PAL) ramps -- which prevent unsteady air flow under tank cable trays and pressurization lines on the external tank’s surface -- were removed after a piece of insulating foam came off this area during Discovery's flight in 2005.
The same sort of foam loss and subsequent damage to the spacecraft caused the space shuttle Columbia accident and the loss of its seven-member crew in 2003.
COMPLETING SPACE STATION ASSEMBLY
With Discovery and its crew safely home, the stage is set to resume assembly of the International Space Station.
To the international partners of the space station, at a press conference after the Discovery landing, NASA Administrator Mike Griffin said, “Thanks ... for hanging in there with us over the last three and a half years since we lost Columbia. The nation vowed to return the shuttle to flight and to finish the station. That was a controversial decision but we have kept to that path and we will continue to keep to that path.”
Preparations continue for the launch of space shuttle Atlantis (STS-115) in late August or early September to deliver more truss segments to the station.
“There are a lot of challenges in front of us,” said NASA Associate Administrator for Space Operations Bill Gerstenmaier. “We’re gearing up for the next flights and space station assembly. Those will be as challenging or more challenging that what we’ve just done, but the teams are working real hard, not only on the next flight but the flights after that.”
Atlantis is expected to be moved to the launch pad in early August, and NASA managers plan to meet shortly thereafter to clear the shuttle for its first mission since October 2002.
“We’ve got 16 flights to go to assemble the station and hopefully do a Hubble [Space Telescope] repair, and that’s what we want to do,” Griffin said, “but we’ve got to take that one flight at a time.”
The 14-year-old Hubble telescope could be useless by 2009 unless new batteries and gyroscopes are delivered and installed.
MOST PHOTOGRAPHED MISSION
STS-121 was the most photographed shuttle mission, with more than 100 high-definition, digital, video and film cameras documenting the launch and climb to orbit.
Data from these images helped assess whether the orbiter sustained damage and whether that damage posed a risk to Discovery's return to Earth.
The STS-121 mission also bolstered the International Space Station. Fossum and Sellers, with the help of crewmates, completed three spacewalks. The third spacewalk was confirmed after mission managers determined there was enough electrical power to add another day to the flight.
The astronauts tested the boom extension to the shuttle's 50-foot robotic arm as a work platform. They removed and replaced a cable that provides power, command and data and video connections to the station's mobile transporter rail car.
The transporter is used to move a platform containing the station's robotic arm along the truss of the complex.
During the third spacewalk, the astronauts tested techniques for inspecting and repairing the reinforced carbon-carbon segments that protect the shuttle's nose cone and leading edge of the wings.
FULL STATION CREW
Discovery delivered a third crewmember and more than 12,700 kilograms of equipment and supplies to the station.
European Space Agency astronaut Thomas Reiter joined Russian Pavel Vinogradov and American Jeff Williams. This is the first time since May 2003 that the station crew has had three members.
President Bush called the astronauts July 11 to congratulate them on a successful mission and thank them for their work to further the U.S. Vision for Space Exploration, which calls for NASA to send people back to the moon, and then to Mars and beyond.
STS-121 was the 115th shuttle mission and the 18th to visit the space station. The landing marked Discovery’s 32nd flight. Discovery will now be serviced and prepared for its next mission, STS-116, scheduled for December.
More information about STS-121 and the upcoming STS-115 mission is available at the NASA Web site.
For ongoing coverage of the U.S. space program, see Science and Technology.
(The Washington File is a product of the Bureau of International Information Programs, U.S. Department of State. Web site: http://usinfo.state.gov)
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