(CNN) -- It's the most complex construction project in history.
Flying 250 miles overhead, the international space station can be seen with the naked eye, orbiting the Earth every 90 minutes, usually carrying a crew of six. Now, before construction of the station is even complete, there is already talk of when the lights will be turned off.
NASA is waiting for the Obama administration to decide how much longer the station will fly and exactly which direction the U.S. space agency will take next -- a return to the moon, or maybe a trip to Mars?
The initial phase of the international space station was launched in 1998, although the station is still being expanded. The U.S. is one of 16 countries that help build and operate the station, whose laboratory runs a number of science experiments, including measuring the effects of space