Astronaut Zhai Zhigang of China waves the national flag after exiting the Shenzhou VII space craft in this September 27, 2008 video grab. Zhai became the first Chinese man to walk in space on Saturday, clambering out of the space craft in a technological feat that Beijing wants the world to marvel about. REUTERS/CCTV via Reuters TV 

The first American spacewalk, conducted in 1965 by Gemini 4 astronaut Ed White, is seen during a screening of a selection from over 100 hours of high definition archival footage of space travel that Discovery Communications is returning to NASA, on Capitol Hill in Washington May 6, 2008. REUTERS/Larry Downing (UNITED STATES) 

Flight engineer Clayton Anderson prepares to jettison video stanchion frame while attached to the International Space Station's robot arm July 23, 2007. The spacewalking pair will install a televison camera stanchion and jettison a 1,400-pound Early Ammonia Servicer during the planned 6 hour-plus spacewalk.REUTERS/NASA (UNITED STATES) 

Flight engineer Clayton Anderson jettisons the video stanchion frame while attached to the International Space Station's robot arm July 23, 2007. The spacewalking pair will install a televison camera stanchion and jettison a 1,400-pound Early Ammonia Servicer during the planned 6 hour-plus spacewalk. REUTERS/NASA (UNITED STATES) 

Astronaut Robert Curbeam works at the end of the International Space Station's S1 truss segment December 16, 2006 as he and fellow spacewalker Sunita Williams work outside the orbiting laboratory in this video grab. FOR EDITORIAL USE ONLY REUTERS/NASA 

European Space Agency astronaut Christer Fuglesang of Sweden takes time out from his work to wave during his second spacewalk, with the earth in the background, in this digital still photo released by NASA December 15, 2006. EDITORIAL USE ONLY REUTERS/NASA (UNITED STATES) 

European Space Agency astronaut Christer Fuglesang of Sweden works during his second spacewalk, with the earth in the background, in this digital still photo released by NASA December 15, 2006. FOR EDITORIAL USE ONLY REUTERS/NASA (UNITED STATES) 

A NASA computer graphic shows the position of Mikhail Tyurin when he hits a golf ball during his spacewalk from the International Space Station November 22, 2006. The commercial activity, sponsored by a Canadian golf company through a contract with the Russian Federal Space Agency, is expected to result in the longest golf shot ever made. EDITORIAL USE ONLY REUTERS/NASA (UNITED STATES) 

Heidemarie Stefanyshyn-Piper, STS-115 mission specialist, is pictured during a spacewalk with astronaut Joe Tanner (not in frame) from the International Space Station September 12, 2006. EDITORIAL USE ONLY REUTERS/NASA (UNITED STATES) 

European Space Agency (ESA) astronaut Thomas Reiter from Germany and NASA astronaut Jeff Williams from the U.S. are seen on a video screen during a live transmission from the International Space Station ISS to the Aerospace Centre in Oberpfaffenhofen, 20 kilometres west of Munich, August 3, 2006. Reiter is the first ESA astronaut as member of a long-term mission to the ISS and the first European who left the station's Questairlock hatch for a spacewalk scheduled for six hours, 20 minutes. REUTERS/Alexandra Winkler (GERMANY) 

European Space Agency (ESA) astronaut Thomas Reiter from Germany and NASA astronaut Jeff Williams from the U.S. are seen on a video screen during a live transmission from the International Space Station ISS to the Aerospace Centre in Oberpfaffenhofen, 20 kilometres west of Munich, August 3, 2006. Reiter is the first ESA astronaut as member of a long-term mission to the ISS and the first European who left the station's Questairlock hatch for a spacewalk scheduled for six hours, 20 minutes. REUTERS/Alexandra Winkler (GERMANY) 

European Space Agency (ESA) astronaut Thomas Reiter from Germany and NASA astronaut Jeff Williams from the U.S. are seen on a video screen during a live transmission from the International Space Station ISS to the Aerospace Centre in Oberpfaffenhofen, 20 kilometres west of Munich, August 3, 2006. Reiter is the first ESA astronaut as member of a long-term mission to the ISS and the first European who left the station's Questairlock hatch for a spacewalk scheduled for six hours, 20 minutes. REUTERS/Alexandra Winkler (GERMANY) 

- VIDEO IMAGE - International Space Station Commander Pavel Vinogradov of Russia (R) and U.S. Science Officer Jeffrey Williams (top) near the PIRS docking module (L) during their spacewalk June 1, 2006. [Vinogradov and Williams, wearing Russian Orlon spacesuits, will repair a vent on the station's oxygen-producing Elektron unit, retrieve experiment results and replace a camera on the station's rail car system during their scheduled 5-hour 41-minute spacewalk.]
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- VIDEO IMAGE - U.S. Science Officer Jeffrey Williams (L) in a televised view during his spacewalk with International Space Station Commander Pavel Vinogradov of Russia (obscured, R) from aboard the orbiting laboratory June 1, 2006. [Vinogradov and Williams, wearing Russian Orlon spacesuits, will repair a vent on the station's oxygen-producing Elektron unit, retrieve experiment results and replace a camera on the station's rail car system during their scheduled 5-hour 41-minute spacewalk.]
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- PHOTO TAKEN 03AUG05 - The Space Shuttle Discovery, docked to the Destiny laboratory of International Space Station, is featured in this image photographed by [astronaut Stephen K. Robinson (out of frame)], STS-114 mission specialist, during a spacewalk August 3, 2005. [Astronaut Soichi Noguchi, a mission specialist representing Japan Aerospace Exploration Agency (JAXA), is partially visible between Discovery's payload bay and Destiny. The blackness of space and Earth's horizon formed the backdrop for the image.] Picture taken August 3, 2005.
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- PHOTO TAKEN 03AUG05 - The Space Shuttle Discovery, docked to the Destiny laboratory of International Space Station, is featured in this image photographed by astronaut Stephen K. Robinson (out of frame), STS-114 mission specialist, during a spacewalk August 3, 2005. Astronaut Soichi Noguchi, a mission specialist representing Japan Aerospace Exploration Agency (JAXA), is partially visible between Discovery's payload bay and Destiny. The blackness of space and Earth's horizon formed the backdrop for the image. Picture taken August 3, 2005.
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A close-up view of a portion of the thermal protection tiles on Space Shuttle Discovery?s underside is featured in this image photographed by astronaut Stephen K. Robinson (out of frame), STS-114 mission specialist, during the mission's third session of extravehicular activities (EVA), August 3, 2005. [While perched on a Space Station truss, astronaut Soichi Noguchi (background), mission specialist representing Japan Aerospace Exploration Agency (JAXA), acts as observer and communication relay station between fellow spacewalker Robinson and astronaut Andrew S. W. Thomas aboard Discovery.] ? EDITORIAL USE ONLY 

Discovery's underside floats over the Earth in this first-of-its-kind view, taken during astronaut Steve Robinson's dramatic August 3, 2005 spacewalk. Riding the International Space Station's robot arm, Robinson ventured under the Shuttle to remove a pair of gap fillers sticking out between tiles on the orbiter's heat shield. ? EDITORIAL USE ONLY 

Astronaut Soichi Noguchi of Japan waves from the Shuttle payload bay, backdropped by the Earth below, August 1, 2005. During the mission's second spacewalk, Noguchi and Discovery crewmate [Steve Robinson replaced a failed gyroscope which keeps the International Space Station in the proper position in orbit. Robinson] will use the mission's third spacewalk on Wednesday to remove two gap fillers that are protruding from areas between heat-shielding tiles on Discovery's underbelly. ? EDITORIAL USE ONLY 

Astronaut Soichi Noguchi, STS-114 mission specialist representing Japan Aerospace Exploration Agency, acts as observer and communication relay station between fellow spacewalker [Stephen K. Robinson (out of frame) and astronaut Andrew S. W. Thomas aboard Space Shuttle] Discovery, while perched on a Space Station truss during a part of the mission?s third session of extravehicular activities (EVA) on August 3, 2005. [A portion of the thermal protection tiles on Discovery's underside is visible at lower left. The image was photographed by Robinson using a digital camera.]
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Astronaut Soichi Noguchi, STS-114 mission specialist representing Japan Aerospace Exploration Agency (JAXA), acts as observer and communication relay station between fellow spacewalker [Stephen K. Robinson (out of frame) and astronaut Andrew S. W. Thomas aboard Space Shuttle] Discovery, while perched on a Space Station truss during a part of the mission's third session of extravehicular activities (EVA) on August 3, 2005. [A portion of the thermal protection tiles on Discovery's underside is visible at lower left. The image was photographed by Robinson using a digital camera].
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- TELEVISION IMAGE - Spacewalk choreographer Andy Thomas of Australia holds up the two gap fillers removed from underneath Discovery by spacewalker [Steve Robinson] in this image from NASA television from the mid deck of the orbiter, August 4, 2005.
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This image taken aboard the Shuttle Discovery August 2, 2005 shows the modifications the crew has made to a hacksaw Mission Specialist [Steve Robinson] will carry with him during the third spacewalk. The hacksaw could be used if needed to cut off a thermal protection system gap filler that is protruding from the underside of Discovery.
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- TELEVISION IMAGE - Astronaut Soichi Noguchi of Japan is seen in the payload bay of the Discovery near the airlock at the beginning of his third spacewalk of mission STS-114 August 3, 2005. [Noguchi and fellow astronaut Steve Robinson] will install a new equipment stowage rack, a new camera and light system and perform other space station construction and maintenance tasks.
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- TELEVISION IMAGE - A close-up of the bubble protruding from the thermal blanket near the commander's window on the port side of the shuttle Discovery is shown in this image from the Orbital Boom Sensor System (OBSS) camera on Discovery's robot arm August 4, 2005. NASA engineers are studying the sensor system's images of the bubble to determine how to address the issue and if a fourth spacewalk will be required for repairs. The thermal blanket is the final hurdle that mission managers must overcome before clearing the orbiter's heat shield for landing ??? USE ONLY
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- TELEVISION IMAGE - A bubble protrudes from the thermal blanket near the commander's window on the port side of the shuttle Discovery in this image from the Orbital Boom Sensor System (OBSS) camera on Discovery's robot arm August 4, 2005. NASA engineers are meeting to study the 3D, thermal and high resolution television images of the bubble to determine how to address the issue and if a fourth spacewalk will be required to repair the thermal blanket before re-entry. ??? USE ONLY
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Wayne Hale, deputy shuttle program manager, addresses the media during the shuttle Discovery status briefing at the Johnson Space Center in Houston, Texas August 4, 2005. NASA on Thursday cleared Discovery to return home after dismissing lingering concerns about its condition, and told the crew to pack up their spacesuits because there was no need for a fourth spacewalk. REUTERS/Tim Johnson TCJ/VP 

Wayne Hale, deputy shuttle program manager, addresses the media during the shuttle Discovery status briefing at the Johnson Space Center in Houston, Texas August 4, 2005. NASA on Thursday cleared Discovery to return home after dismissing lingering concerns about its condition, and told the crew to pack up their spacesuits because there was no need for a fourth spacewalk. REUTERS/Tim Johnson TCJ/VP 

- TELEVISION IMAGE - View of the shuttle from the helmet cam of astronaut Soichi Noguchi of Japan after fellow spacewalker Steve Robinson successfully removed gap fillers from the underside of Discovery August 3, 2005.
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The STS-114 crew captured this view of Earth from the Shuttle-Station complex on August 3, 2005, day nine of the mission. [Spacewalking astronaut Steve Robinson] plucked a couple of loose fibre strips from Space Shuttle Discovery's belly on Wednesday in an unprecedented repair to the shuttle's heat shield.
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Begley, Lead Spacewalk Officer of STS114, smiles as she gestures after at Discovery status briefing at Johnson Space Center in Houston. Cindy Begley (R), Lead Spacewalk Officer of STS114, smiles as she gestures after the Shuttle Discovery status briefing at the Johnson Space Center in Houston August 3, 2005. Astronaut Steve Robinson ventured to the bottom of space shuttle Discovery on Wednesday for the first time and successfully plucked two protruding cloth fillers from between ceramic tiles on the shuttle's heat shield. At left is Mark Ferringg, Lead Space Station Flight Director. REUTERS/Tim Johnson 

Cindy Begley, the lead spacewalk officer of STS114, addresses the media following a very successful spacewalk to repair heat shield tile fillers, during the Shuttle Discovery status briefing at the Johnson Space Center in Houston, August 3, 2005. REUTERS/Tim Johnson TCJ/TC 

Ferring, Lead Space Station Flight Director, and Begley, Lead Spacewalk Officer of STS114, smile at Johnson Space Center in Houston. Mark Ferring (L), Lead Space Station Flight Director, and Cindy Begley, Lead Spacewalk Officer of STS114 smile after the Shuttle Discovery status briefing at the Johnson Space Center in Houston, August 3, 2005. Astronaut Steve Robinson ventured to the bottom of space shuttle Discovery on Wednesday for the first time and successfully plucked two protruding cloth fillers from between ceramic tiles on the shuttle's heat shield. REUTERS/Tim Johnson 

Visitors to the Smithsonian Air and Space Museum in Chantilly, Virgina, stop in front of a prototype of Space Shuttle Enterprise August 3, 2005. Spacewalking astronaut Steve Robinson plucked a couple of loose fiber strips from Discovery's belly on Wednesday in an unprecedented repair to the shuttle's heat shield. REUTERS/Jason Reed 

Visitors to the Smithsonian Air and Space Museum in Chantilly, Virgina, inspect a prototype of Space Shuttle Enterprise August 3, 2005. Spacewalking astronaut Steve Robinson plucked a couple of loose fiber strips from Discovery's belly on Wednesday in an unprecedented repair to the shuttle's heat shield. REUTERS/Jason Reed JIR/TC 

Visitors to the Smithsonian Air and Space Museum in Chantilly, Virgina, inspect a prototype of Space Shuttle Enterprise August 3, 2005. Spacewalking astronaut Steve Robinson plucked a couple of loose fiber strips from Discovery's belly on Wednesday in an unprecedented repair to the shuttle's heat shield. REUTERS/Jason Reed JIR/TC 

- TELEVISION IMAGE - The external stowage platform ESP-2 (L) is seen attached to the space station's robotic arm ready to be moved into position and installed by spacewalkers [Steve Robinson of the U.S. and Soichi Noguchi of Japan] on the third spacewalk of Discovery's mission STS-114 August 3, 2005. The International Space Station's Destiny laboratory module and Quest airlock can be seen against the backdrop of the earth.
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- PHOTO TAKEN 30JUL05 - Astronauts Steve Robinson (L) and Soichi Noguchi of the Japan Aerospace Exploration Agency take a break onboard Space Shuttle Discovery, after their successful spacewalk earlier in the day July 30, 2005. Photo taken on July 30, 2005. EDITORIAL USE ONLY 

- TELEVISION IMAGE - Astronaut Soichi Noguchi of Japan (C) holds the Control Moment Gyroscope after removing it from the International Space Station's Z-1 truss as fellow spacewalker Steve Robinson (L) stands by August 1, 2005. Noguchi is standing on a platform on the end of the station's Canadarm2 which will transport Noguchi and the gyroscope to Discovery's payload bay. ??? USE ONLY
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- TELEVISION IMAGE -Astronaut Steve Robinson of the U.S. works with a digital camera in the payload bay of shuttle Discovery during his spacewalk with [Soichi Noguchi of Japan (unseen)] August 1, 2005. ??? USE ONLY
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- TELEVISION IMAGE - Astronaut Steve Robinson of the U.S. takes a photograph of fellow spacewalker Soichi Noguchi of Japan, as Noguchi waves his gloved hand, in the payload bay of Discovery during their spacewalk August 1, 2005. ??? USE ONLY
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- TELEVISION IMAGE - Astronaut Steve Robinson of the U.S. works in the payload bay of Discovery in this view from Japanese astronaut Soichi Noguchi's helmet camera during their spacewalk, August 1, 2005. ??? USE ONLY
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- TELEVISION IMAGE - Astronaut Steve Robinson of the U.S. is photographed in Discovery's payload bay with the Earth in the background by fellow spacewalker [Soichi Noguchi of Japan in this helmet camera view during their spacewalk]. ??? USE ONLY
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- TELEVISION IMAGE - Astronaut Steve Robinson of the U.S. works in the payload bay of Discovery with the failed Control Moment Gyro (upper left) and the new gyro (R) shown in this view from the helmet camera of fellow astronaut [Soichi Noguchi of Japan] during their spacewalk. ??? USE ONLY
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Cindy Begley, the Lead Spacewalk Officer of STS114, answers questions from the media after shuttle Discovery's status briefing at the Johnson Space Center. Cindy Begley, the Lead Spacewalk Officer of STS114, answers questions from the media after shuttle Discovery's status briefing at the Johnson Space Center, August 1, 2005. REUTERS/Tim Johnson 

Cindy Begley, the Lead Spacewalk Officer of STS114, entertains the media's questions about the possible repair and procedures of Space Shuttle Discovery's heat shield tile gap filler after the mission status briefing at the Johnson Space Center, August 1, 2005. Two spacewalking astronauts replaced a broken steering device on the International Space Station on Monday and prepared for a possible new and untested venture to fix the shuttle Discovery's heat shield. REUTERS/Tim Johnson 

Phil Engelauf (L), Mission Operations Representative for STS114, Mark Ferring (C), Lead Space Station Flight Director, and Cindy Begley, Lead Spacewalk Officer of STS114, attend a shuttle Discovery status briefing at the Johnson Space Center, August 1, 2005. REUTERS/Tim Johnson TCJ/DY 

Astronauts Robinson and Noguchi prepare for the first of three spacewalks in space shuttle discovery's airlock. Astronaut Steve Robinson (L) and Japan Aerospace Exploration Agency Astronaut Soichi Noguchi prepare for the first of three STS-114 spacewalks in space shuttle Discovery's airlock during flight day 5, July 30, 2005. Photo taken on July 30, 2005. EDITORIAL USE ONY REUTERS/NASA/Handout 

Cindy Begley uses her hands to demonstrate some intricate details of Saturday's spacewalk at Johnson Space Center in Houston. Cindy Begley, Lead Spacewalk Officer for STS114, uses her hands to demonstrate some intricate details of Saturday's spacewalk to members of the Japanese press during a shuttle status briefing at Johnson Space Center in Houston July 30, 2005. Two shuttle Discovery astronauts completed a seven-hour spacewalk on Saturday to restore a critical steering device on the International Space Station and test shuttle heat shield repairs that NASA hopes will prevent another Columbia disaster. REUTERS/Tim Johnson 

Phil Engelauf answers questions from the media after a shuttle status briefing at Johnson Space Center in Houston. Phil Engelauf, Mission Operations Representative for STS114, answers questions from the media after a shuttle status briefing at Johnson Space Center in Houston July 30, 2005. Two shuttle Discovery astronauts completed a seven-hour spacewalk on Saturday to restore a critical steering device on the International Space Station and test shuttle heat shield repairs that NASA hopes will prevent another Columbia disaster. REUTERS/Tim Johnson 

Phil Engelauf (L), Mission Operations Representative for STS114, Mark Ferring (C), the lead Space Station Flight Director and Cindy Begley (R), the lead Spacewalk Officer, address the media at the Discovery shuttle status briefing at the Johnson Space Center in Houston July 30, 2005. REUTERS/Tim Johnson TCJ/YH 

Cindy Begley uses her hands to demonstrate some intricate details of spacewalk at Johnson Space Center in Houston. Cindy Begley, Lead Spacewalk Officer for STS114, uses her hands to demonstrate some intricate details of Saturday's spacewalk to members of the Japanese press during a shuttle status briefing at Johnson Space Center in Houston July 30, 2005. REUTERS/Tim Johnson 

Astronaut Soichi Noguchi of Japan holds up a photo of STS-114 alongside US astronaut Stephen Robinson in Houston. Astronaut Soichi Noguchi of Japan (L) holds up a photo of STS-114 mission specialist and fellow spacewalker Stephen Robinson (R) playing guitar during his stint aboard the MIR space station, while introducing Robinnson during the crew press conference, April 7, 2005 at the Johnson Space Center in Houston. Launch for the shuttle with a crew of seven is scheduled for May 15 on a mission to the International Space Station on the first mission since the shuttle Columbia accident in 2003. REUTERS/Richard Carson 

Japan Aerospace Exploration Agency astronaut Soichi Noguchi of Japan talks about his spacesuit and his planned spacewalks from the Space Shuttle Discovery April 6, 2005 at the Johnson Space Center in Houston. [Noguchi and fellow spacewalker Stephen Robinson are scheduled to make three spacewalks in support of the International Space Station during the Shuttle's return to flight scheduled for May.] 

Japan Aerospace Exploration Agency astronaut Soichi Noguchi of Japan talks about his spacesuit and his planned spacewalks from the Space Shuttle Discovery. Japan Aerospace Exploration Agency astronaut Soichi Noguchi of Japan talks about his spacesuit and his planned spacewalks from the Space Shuttle Discovery April 6, 2005 at the Johnson Space Center in Houston. Noguchi and fellow spacewalker Stephen Robinson are scheduled to make three spacewalks in support of the International Space Station during the Shuttle's return to flight scheduled for May. REUTERS/Richard Carson 

Nasa astronaut Stephen Robinson (L) and Japan Aerospace Exploration Agency astronaut Soichi Noguchi (R) of Japan talk about their planned spacewalks from the Space Shuttle Discovery at the Johnson Space Center in Houston, April 6, 2005. Robinson and Noguchi are scheduled to make three spacewalks in support of the International Space Station during the Shuttle's return to flight scheduled for May. REUTERS/Richard Carson RJC 

- TELEVISION IMAGE - Russian cosmonaut Salizhan Sharipov (top) deploys the Nanosatellite outside the PIRS docking station during his spacewalk aboard the International Space Station March 28, 2005. Sharipov and [U.S. Astronaut Chiao] began a spacewalk on Monday to install equipment to enable the European Space Agency to send its first cargo ship to the International Space Station, mission control said. ??? USE ONLY 

- TELEVISION IMAGE - Russian cosmonaut Salizhan Sharipov works outside the PIRS docking station during his spacewalk aboard the International Space Station March 28, 2005. Sharipov and [U.S. Astronaut Chiao] began a spacewalk on Monday to install equipment to enable the European Space Agency to send its first cargo ship to the International Space Station, mission control said. ??? USE ONLY 

- TELEVISION IMAGE - Expedition 10 Commander Leroy Chiao (Bottom) and Flight Engineer Salizhan Sharipov (Top) work at the end of their six-hour spacewalk from the International Space Station, January 26, 2005. Chiao and Sharipov installed a work platform and experiments on the outside of the station and checked vents that help control the Station's atmosphere. The spacewalk is the 57th conducted aboard the Station and the 32nd to be based out of the orbital outpost.
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- TELEVISION IMAGE - Expedition 10 Commander Leroy Chiao and Flight Engineer Salizhan Sharipov work during their spacewalk from the International Space Station, January 26, 2005. Chiao and Sharipov are working to install a work platform and experiments on the outside of the station as well as checking vents that help control the Station's atmosphere. The spacewalk is the 57th conducted aboard the Station and the 32nd to be based out of the orbital outpost. ? QUALITY DOCUMENT