The International Space Station is visible in this photo taken by an STS-129 crew member on Atlantis soon after the station and shuttle undocked on November 25, 2009, in this NASA handout image. The International Space Station celebrates its 15 year anniversary of human occupancy on November 2. (Photo by Reuters/NASA)





The International Space Station is seen with the docked space shuttle Endeavour in this photo taken by Expedition 27 crew member Paolo Nespoli from the Soyuz TMA-20 following its undocking and is the first-ever image of a space shuttle docked to the ISS, on May 23, 2011, in this NASA handout image. (Photo by Reuters/NASA)





Dwarfed by the International Space Station NASA astronauts Andrew Feustel (R) and Greg Chamitoff (L)work during their first spacewalk of the STS-134 mission in support of construction and maintenance, on May 20, 2011, in this NASA handout image. (Photo by Reuters/NASA)





Canadian Space Agency astronaut Chris Hadfield strums his guitar in the International Space Station's Cupola on December 25, 2012, in this NASA handout image. (Photo by Reuters/NASA)





NASA spacewalker Mike Fossum's helmet visor mirrors a panoramic scene of the docked International Space Station with the space shuttle Atlantis and the blue and white Earth below, on July 12, 2011, in this NASA handout image. (Photo by Reuters/NASA)





Astronaut Mike Hopkins, Expedition 38 Flight Engineer, is shown in this handout photo provided by NASA as he participates in the second of two spacewalks which took place on December 24, 2013, in this NASA handout image. (Photo by Reuters/NASA)





The International Space Station is seen over Rio Negro, Argentina after it undocked from the Space Shuttle Atlantis on February 16, 2001, in this NASA handout image. (Photo by Reuters/NASA)





The Aurora Australis or the Southern Lights can be seen on the Earth's horizon in this panoramic view from the International Space Station looking past the docked space shuttle Atlantis' cargo bay on July 14, 2011, in this NASA handout image. (Photo by Reuters/NASA)





Space Shuttle Atlantis Astronauts, STS-110 mission commander Michael J. Bloomfield (C-foreground), pilot Stephen N. Frick (bottom right), Steven L. Smith (TOPL), Ellen Ochoa, and Lee M. E. Morin (UPSIDE DOWN)pose in the International Space Station's Destiny laboratory April 13, 2002, in this NASA handout image. (Photo by Reuters/NASA)





The International Space Station is backdropped against a heavily cloud-covered part of Earth as the orbital outpost moves away from the space shuttle Discovery August 6, 2005, in this NASA handout image. (Photo by Reuters/NASA)





A STS-96 crew member aboard Discovery recorded this image of the International Space Station (ISS) with a 70mm camera during a fly-around following separation of the two spacecraft on June 3, 1999, in this NASA handout image. Lake Hulun Nur in the People's Republic of China is visible in the lower left portion of the frame. (Photo by Reuters/NASA)





NASA astronaut Reid Wiseman and European Space Agency astronaut Alexander Gerst (not shown) works outside the space station's Quest airlock in the first of three spacewalks for the Expedition 41 crew aboard the International Space Station in this NASA image released October 8, 2014. (Photo by Reuters/NASA)





NASA astronaut Sunita Williams, Expedition 32 flight engineer, takes part in the mission's third session of extravehicular activity outside the International Space Station on September 5, 2012, in this NASA handout image. (Photo by Reuters/NASA)





Expedition 1 crew members (L-R): Commander Bill Shepherd, Flight Engineers Sergei Krikalev and Yuri Gidzenko pose with a model of their home away from home in this November 2, 2012, NASA released file image. (Photo by Reuters/NASA)





A photo of the aurora australis taken during a geomagnetic storm from the International Space Station on May 29, 2010. (Photo by Reuters/ISS Crew Earth Observations experiment and Image Science & Analysis Laboratory, Johnson Space Center)





The International Space Station is seen from the space shuttle Discovery after the undocking of the two spacecraft on March 7, 2011. (Photo by Reuters/NASA)





The space shuttle Discovery after it undocked from the International Space Station, in a photo taken more than 200 miles above Earth and released on March 9, 2011. (Photo by Reuters/NASA)





Astronaut Robert L. Satcher Jr. works outside the International Space Station on November 19, 2009. (Photo by Reuters/NASA)





Siberia's Lake Baikal is pictured in this photo taken by astronaut Chris Hadfield on February 26, 2013. (Photo by Chris Hadfield/Reuters/NASA)





Space tourist Anousheh Ansari while enroute to the International Space Station on September 18, 2006. (Photo by Reuters/NASA)





A view of Earth from the Cupola on the earth-facing side of the International Space Station on June 12, 2013. Visible in the top left foreground is a Russian Soyuz crew capsule. In the lower right corner, a solar array panel can be seen. (Photo by Reuters/NASA)





Astronaut Dave Wolf transports the Linear Drive Unit and two other parts to the station's External Stowage Platform 3 for long-term storage on July 20, 2009. (Photo by Reuters/NASA)





A Russian cosmonaut during a mission in open space outside the International Space Station on August 24, 2012. (Photo by Reuters/Roscosmos)





One of two Soyuz spacecrafts docked with the International Space Station on July 25, 2009. (Photo by Reuters/NASA)





Astronaut Karen Nyberg looks through a window in the newly installed Kibo laboratory of the International Space Station on June 11, 2008. (Photo by Reuters/NASA)





An unprecedented view of the space shuttle Atlantis, appearing like a bean sprout against clouds and city lights on its way home, as photographed from a window on the International Space Station on July 21, 2011. Airglow over Earth can be seen in the background. (Photo by Reuters/NASA)





The space shuttle Endeavour silhouetted against the backdrop of Earth's horizon prior to docking with the International Space Station on February 9, 2010. (Photo by Reuters/NASA)





Japanese Aerospace Exploration Agency astronaut Koichi Wakata begins a workout on the Advanced Resistive Exercise Device in the Unity node on March 21, 2009. (Photo by Reuters/NASA)





The sun about to come up over the South Pacific Ocean, taken from aboard the International Space Station a few hundred miles east of Easter Island on May 9, 2013. (Photo by Reuters/NASA)





NASA astronaut Greg Chamitoff uses a laptop on the aft flight deck of space shuttle Endeavour during rendezvous and docking operations with the International Space Station on May 18, 2011. (Photo by Reuters/NASA)





A crescent moon rises over the cusp of the Earth's atmosphere in this picture taken by Japan Aerospace Exploration Agency astronaut Koichi Wakata onboard the International Space Station on February 1, 2014. Distinct colors are visible because the dominant gases and particles in each layer of the atmosphere act as prisms, filtering out certain colors of light. (Photo by Reuters/NASA)





A large mass of storm clouds over the Atlantic Ocean near Brazil and the Equator taken by a crew member aboard the International Space Station on July 4, 2013. A Russian spacecraft, docked to the orbiting outpost, partially covers a small patch of sunlight on the ocean waters in a break in the clouds. (Photo by Reuters/NASA)





Backdropped by Earth's horizon and the blackness of space, a portion of the International Space Station is featured in this image photographed by a crew member aboard the station in this photo released by NASA and taken February 15, 2010. (Photo by Reuters/NASA)





Backdropped by a night time view of the Earth and the starry sky, the Space Shuttle Endeavour is seen docked to the International Space Station on May 28, 2011. (Photo by Reuters/NASA)