Lockheed Martin Space Systems Company is one of the four major business divisions of Lockheed Martin. It has its headquarters in Denver, Colorado with additional sites in Sunnyvale, California; Santa Cruz, California;  Huntsville, Alabama; and elsewhere in the US and UK. The division currently employs about 16,000 people, and its most notable products are commercial and military satellites, space probes, missile defense systems, NASA's Multi-Purpose Crew Vehicle (formerly Orion), and the Space Shuttle External Tank.