50 years of Nasa space travel
20 July 2011 Last updated at 22:19 BST
Space shuttle Atlantis is ready to make one last descent to Earth. Atlantis, like Discovery and Endeavour before it, is being retired.
The orbiter and its crew of four are scheduled to hit the runway at the Kennedy Space Center in Florida just before sunrise on Thursday.
Nasa has been at the forefront of space travel for 50 years after it was created by President Dwight D Eisenhower in 1958.
It has experienced highs and lows and many memorable moments.