The International Space Station is an orbiting space laboratory, assembled through a decades-long collaboration of countries. The 360-ton space station is larger than a five-bedroom house -- just much longer and narrower. It has enough room for six sleeping quarters, a gym, a 360-degree viewing window, and areas to conduct a wide array of science experiments. "We've had continuous human presence on the space station for 19 years now," said NASA spokeswoman Stephanie Schierholz. "It is an unprecedented international collaboration among nations."