A classified U.S. government satellite was launched into orbit on a cloudy night at Cape Canaveral Air Force Station in Florida Tuesday, blasting off with an Atlas 5 rocket and dozens of conspiracy theories. The CLIO satellite was built by Lockheed Martin and successfully entered orbit three hours after launch, but few seem to know for what purpose.

The mystery satellite has been a popular source of speculation for amateur astronomers and conspiracy theorists, in no small part because Lockheed Martin Corp. (NYSE:LMT) is one of the world’s largest defense contractors. Government scientists are mum on the issue, as well, though Atlas rockets, which carried the CLIO into space, are known to carry weather, telecommunications and national security equipment into space frequently.

The CLIO satellite is based on the a21000 bus that Lockheed produces for commercial communication satellite, according to NASASpaceflight.com. This similarity has fueled speculation that the CLIO launched Tuesday evening is a replacement for the PAN satellite, though it’s unclear if the missions are related.

“Following its launch in September 2009 the satellite was placed into geostationary orbit, and has been moved frequently between orbital shots since entering service,” the space and technology news site reported of the PAN. “It is currently orbiting over the equator at a longitude of 47.5 degrees, off the East coast of Africa …. Communications is one possible application for the CLIO satellite.”  

This launch also came at the end of a busy news day for the space industry. NASA announced that it chose SpaceX and the Boeing Company (NYSE:BA) to build an “American spacecraft” capable of carrying astronauts between Earth and the International Space Station.