MOSCOW, September 9 (RIA Novosti) - The United States has successfully launched an Atlas 5 heavy carrier rocket with a satellite built under a commercial arrangement with the U.S. government.

According to spaceflightnow.com website, the rocket with a PAN satellite on board lifted off from the Kennedy space center in Florida at 5:35 p.m. EDT (21.35 GMT) on Tuesday.

Space experts believe that the PAN satellite, whose development was shrouded in secrecy, will "serve as a communications gap-filler between the aging constellation of Ultra-High Frequency Follow-On (UFO) spacecraft and the sophisticated next-generation Mobile User Objective System that's still being developed," an article on the website said.

The Atlas rocket is powered by Russian-made RD-180 engine, which uses an extremely efficient, high-pressure staged combustion cycle.

Rights to employ the RD-180 were acquired by General Dynamics Space Systems Division (later purchased by Lockheed Martin) in the early 1990s for use in the Evolved Expendable Launch Vehicle (EELV) and the Atlas program.

The RD-180 was first deployed on the Atlas III carrier rocket in May 2000 and powered over 20 Atlas-family delivery vehicles since then.