STS-116 Shuttle Mission Imagery Mission Specialists Robert L. Curbeam (USA) and Christer Fuglesang (Sweden) participate in the first of three planned sessions of extravehicular activity (EVA). Backdropped by a colorful Earth, they work to attach a new truss segment to the ISS to upgrade the power grid. The landmasses depicted are the South Island (left) and North Island (right) of New Zealand. Explanation: The International Space Station (ISS) is the largest human-made object ever to orbit the Earth. The station is so large that it could not be launched all at once -- and is instead built piecemeal with large sections added continually by flights of the Space Shuttle. To function, the ISS needs trusses to keep it rigid and to route electricity and liquid coolants. These trusses are huge, extending over 15 meters long, and with masses over 10,000 kilograms. #science #technology #iss #nasa #space