The contract is the first for a Falcon Heavy rocket, which is being designed to carry more than twice as much as the Boeing-built Delta 4 Heavy launcher, which is currently the biggest rocket in the U.S. fleet.

Terms of the contract were not disclosed, but Space Exploration Technologies, or SpaceX, has said it expects to sell Falcon Heavy flights to commercial customers for about $100 million.

United Launch Alliance, a partnership of Boeing and Lockheed Martin that markets and flies Delta 4 and Atlas 5 rockets, does not disclose prices.

Luxembourg-based, privately held Intelsat currently operates 52 communications satellites and has plans to launch four more spacecraft this year, said company spokesman Alex Horwitz.

The contract with SpaceX is for one satellite launch, he added. A launch site and time frame for the flight were not disclosed.

Intelsat's launch will follow test flights of Falcon Heavy, a rocket based on the company's Falcon 9 rocket which last week launched a Dragon cargo capsule on a test flight to the International Space Station.

SpaceX, which is owned and operated by Internet entrepreneur Elon Musk, has a 12-flight, $1.6 billion contract with NASA to deliver cargo to and from the space station, which orbits about 240 miles above Earth.

Since the space shuttles were retired last year, the United States is dependent on partner countries in Europe, Japan and Russia to fly cargo and crew to the $100 billion outpost.

Falcon 9's launch manifest also includes more than two dozen flights for non-U.S. government and commercial customers, such as Iridium, Asia Satellite Telecommunications Co. and SES.

Falcon Heavy is expected to debut in 2013.

On May 18, Intelsat, the world's biggest operator of satellite services, filed with U.S. regulators to raise up to $1.75 billion in an initial public offering of its common stock. The company operated as an intergovernmental organization for more than 30 years before becoming a private firm in 2001.

Intelsat was purchased in 2008 by Serafina Acquisition Ltd, which is backed by private equity firm Silver Lake, among other funds.

Intelsat posted a net loss of $400 million on revenue of $2.6 billion for the year ending December 31, according to the regulatory filing.

SpaceX, which was founded in 2002, is owned by Musk, other managers and employees, with minority investments from Founders Fund, Draper Fisher Jurvetson, and Valor Equity Partners.

(Editing by Jane Sutton and Kenneth Barry)

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