How many spaceships NASA owns?

As of this writing, NASA has only three (3) working SPACESHIPS (as opposed to total number of SPACECRAFT owned or operating), the space shuttle orbiter vehicles, OV-103 Discovery, OV-104 Atlantis and OV-105 Endeavor.

However, NASA has previously announced its plan to "mothball" the costly space shuttle fleet following the STS-133 shuttle mission to deliver supplies to the International Space Station. The shuttle Discovery is slated to blast off in September 2010 on the eight-day trek that - if NASA's current plan holds - will mark the end of the shuttle era after 29 years of spaceflight.

NASA's lower-cost replacement for the space shuttle fleet has been dubbed Project Constellation.