Space Shuttle Endeavour
The Space Shuttle Endeavour was the fifth American Space shuttle orbiter. Named for the vessel of the 18th century British explorer James Cook and made mainly of spare parts, the orbiter Endeavour was constructed as a replacement for the Space Shuttle Challenger, which was lost in 1986. Many improvements were made during the construction of Endeavour which were used in the retrofits of the other shuttle orbiters.  The Endeavour is one of three active Shuttles (the other two are Discovery and Atlantis).