FACTBOX: Who benefits if NASA buys space flights?

(Reuters) - Companies positioned to take advantage of a proposal for the U.S. government to fly astronauts to the International Space Station commercially include:

* Space Exploration Technologies, or SpaceX, a privately owned company founded by Internet entrepreneur Elon Musk, who also owns electric car start-up Tesla Motors. SpaceX is developing a seven-seat capsule, known as Dragon, and a rocket called Falcon. Price per-seat: About $20 million.

* Northrop Grumman Corp partnered Boeing Co in an unsuccessful bid to build NASA's Orion capsule, its planned follow-up to the space shuttle. It also builds satellites, lasers and military space systems for government and commercial users.

* Lockheed Martin won a $3.9 billion NASA contract to build Orion, that could ferry crews to the space station as well as to the moon. If Orion's Ares 1 launch vehicle is canceled as part NASA's restructuring, the Orion capsule could fly on other rockets.

* Boeing, NASA's prime contractor on the space station, was selected to build part of the Ares 1 launcher and provide avionics.

* Orbital Sciences Corp shares a NASA contract with SpaceX to demonstrate cargo delivery services to the space station. Though its Taurus rocket and Cygnus spacecraft are intended for cargo only, NASA also hired Orbital to develop a launchpad emergency escape system for its Orion spacecraft, whose future as a space station taxi and moonship is uncertain.

* United Launch Alliance, a joint venture of Lockheed Martin and Boeing, to market and launch Delta and Atlas expendable rockets. Among the proposals vetted by President Barack Obama's space program study team was a plan to upgrade the cargo launchers to carry passenger ships.

* Sierra Nevada Corp. bought into the space business with the acquisition of SpaceDev in 2009 and MicroSat Systems in 2008. SNC's Space Systems group is working on a NASA-derived spaceplane called the Dream Chaser.

(Reporting by Irene Klotz; editing by Jane Sutton)