Our outpost in space

Backdropped by Earth, the International Space Station (ISS) is seen photographed from the space shuttle Endeavour after the station and shuttle began their post-undocking relative separation, in this undated NASA handout photo. REUTERS/NASA

Astronaut James H. Newman waves during a spacewalk preparing for the release of the first combined elements of the ISS on November 20, 1998. The Russian-built Zarya module, with its solar array panel visible here, was launched into orbit on November 20, 1998. Two weeks later, December 4, 1998. NASA's space shuttle Endeavour launched Unity, the first U.S. piece of the complex. During three spacewalks on the STS-88 mission, the two space modules built on opposite sides of the planet were joined together in space, making the space station truly international. REUTERS/NASA

The Orbital Sciences Corporation Antares rocket with the Cygnus cargo spacecraft aboard launches from NASA's Wallops Flight Facility in Virginia, September 18, 2013. The spacecraft will deliver about 1,300 lbs of cargo, including food and clothing, to the ISS. REUTERS/Bill Ingalls/NASA

Astronaut Mike Hopkins, Expedition 38 Flight Engineer, participates in the second of two spacewalks which took place on December 24, 2013. The scheduled spacewalks were designed to allow the crew to change out a faulty water pump on the exterior of the Earth-orbiting ISS. REUTERS/NASA

The Soyuz spacecraft prepares to dock with the ISS in this still image taken from video November 7, 2013. REUTERS/NASA TV

NASA astronaut Karen Nyberg participates in an onboard training activity at the robotics workstation in the ISS Cupola, in this image released on August 9, 2013, in preparation for the grapple and berthing of the Japanese "Kounotori" H2 Transfer Vehicle-4 set for August 9, 2013. REUTERS/NASA

NASA astronaut Karen Nyberg, Expedition 37 flight engineer, Russian cosmonaut Fyodor Yurchikhin commander (R), and European Space Agency astronaut Luca Parmitano, flight engineer, pose for a photo in the Kibo laboratory of the ISS in this October 14, 2013. REUTERS/NASA

Backdropped by the blackness of space, the ISS is seen in this image taken by a crew member aboard the Space Shuttle Atlantis during rendezvous and docking activities November 18, 2009. REUTERS/NASA

NASA astronaut Chris Cassidy using a 400mm lens on a digital still camera photographs a target of opportunity on Earth some 250 miles below him from inside the Cupola aboard the ISS in this image released on June 10, 2013. REUTERS/NASA

The ISS crew opens a hatch to begin unloading cargo on September 30, 2013. REUTERS/NASA/Johnson Space Centre

The unmanned U.S. commercial cargo ship Cygnus is seen being attached to the ISS September 29, 2013 in this still image from video. REUTERS/NASA TV

NASA astronaut Karen Nyberg demonstrates how she washes her hair in zero gravity aboard the ISS in this still image taken from video released July 12, 2013. REUTERS/NASA

NASA Expedition 35 Flight Engineer Chris Cassidy conducts a spacewalk to inspect and replace a pump controller box on the ISS's far port truss (P6) leaking ammonia coolant in this NASA handout photo taken May 11, 2013. REUTERS/NASA

Earth is seen behind the ISS from Space Shuttle Discovery as the two spacecraft begin their relative separation on September 8, 2009. REUTERS/NASA

Taking advantage of a weightless environment onboard the Earth-orbiting ISS, Expedition 34 Flight Engineer Chris Hadfield of the Canadian Space Agency juggles some tomatoes March 3, 2013. REUTERS/NASA

Lake Baikal, Siberia, Russia is pictured in thisphoto taken by Canadian astronaut Chris Hadfield February 26, 2013, aboard the ISS. REUTERS/Chris Hadfield/NASA

The Canadarm2 is pictured in this photo taken by Canadian astronaut Chris Hadfield February 25, 2013, aboard the ISS courtesy of NASA. REUTERS/Chris Hadfield/NASA

NASA astronaut Sunita Williams, Expedition 32 flight engineer, takes part in a spacewalk outside the ISS September 5, 2012. REUTERS/NASA

Japan Aerospace Exploration Agency Flight Engineer Akihiko Hoshide takes a ride on the end of the space arm during a spacewalk outside the ISS, August 30, 2012 in this still image taken from video. REUTERS/NASA

Expedition 37 commander Fyodor Yurchikhin holds the Olympic torch that will be used to light the Olympic flame for the 2014 Winter Games in Sochi, Russia after Expedition 38 cosmonaut Mikhail Tyurin handed it over aboard the ISS in this still image from NASA Tv video, November 7, 2013. REUTERS/NASA Tv

The bright sun greets the ISS in this photo taken from the Russian section of the orbital outpost by one of the STS-129 crew members November 22, 2009. REUTERS/NASA