According to the NASA, during the next flight to the moon, U.S. astronauts could work out on the surface of the Earth's satellite as much as 90 days.
Another option includes a seven night stay on the moon.
And in fact, and in another case the crew can number from two to six people.
However, the 90-day mission is considered NASA, as a logical and challenging step, because in 1970, two astronauts spent on the moon a little more than three days.
Recall that George Bush proposed NASA return to the moon as early as 2015 and no later than 2020.
However, the planning of lunar missions is still at a very early stage, and perhaps never will be flying.