Astronauts Tom Marshburn (upper left) and Christopher Cassidy, mission specialists for STS-127, share duties on the fourth spacewalk of Endeavour’s mission, July 24, 2009

Part of the Sinai Peninsula, featuring the Gulf of Suez and the Gulf of Aqaba, photographed by one of the STS-127 crewmembers aboard the Space Shuttle Endeavour while it was docked with the International Space Station, July 24, 2009.

External tank for Space Shuttle Atlantis mission STS-129 is transported into the Vehicle Assembly Building at the Kennedy Space Center August 4, 2009, in Cape Canaveral, Florida.

Space Shuttle Discovery sits atop the crawler transporter at the Kennedy Space Center in Cape Canaveral, Florida, August 4, 2009.

Astronaut F. Story Musgrave, anchored on the Space Shuttle Endeavor’s robotic arm, prepares to be elevated to the top of the Hubble Space Telescope during Hubble’s first servicing mission in 1993.

Shenzhou VII taikonauts (L-R) Jing Haipeng, Zhai Zhiguang and Liu Boming attend an interview at the satellite launch center on September 25, 2008 in Jiuquan, Gansu Province, China.

Astronaut Eugene A. Cernan makes a short checkout of the Lunar Roving Vehicle (LRV) during the Apollo 17 Extravehicular Activity (EVA-1) at the Taurus-Littrow landing site, December 11, 1972.

Reflection in the helmet visor of astronaut Christopher Cassidy, during his second spacewalk July 24, 2009.

The Shenzhou-7 spacecraft sits in its dock at the Jiuquan Satellite Launch Center, September 18, 2008 in Northwest China’s Gansu Province.

Buzz Aldrin, lunar module pilot, walks on the surface of the Moon near the leg of the Lunar Module (LM) “Eagle” during the Apollo 11 exravehicular activity (EVA), 20 July, 1969.

Hurricane Ike is seen as it covers more than half of Cuba on September 9, 2008 from aboard the International Space Station (ISS).

Engineers monitor the operations of the Shenzhou-7 spacecraft during testing at the Jiuquan Satellite Launch Center, September 22, 2008 in Northwest China’s Gansu Province.

Space Shuttle Endeavour launches from launch pad 39A at Kennedy Space Center July 15, 2009 in Cape Canaveral, Florida.