Dec 22 - Billionaire Elon Musk's SpaceX is scheduled on Saturday to launch a long-delayed U.S. military navigation satellite, which if successful would mark the rocket company's first national security space mission for the United States.
A Falcon 9 rocket carrying a roughly $500 million GPS satellite built by Lockheed Martin Corp was due to blast off from Florida's Cape Canaveral around 9 a.m. (1400 GMT), privately held SpaceX said.
A successful launch - SpaceX's fourth attempt in a week after technical and weather delays - would be a significant victory for Musk's rocket company, which has spent years trying to break into the lucrative market for military space launches long-dominated by Lockheed and Boeing Co.
SpaceX sued the U.S. Air Force in 2014 in protest over the military's award of a multibillion-dollar, non-compete contract for 36 rocket launches to United Launch Alliance, a partnership of Boeing and Lockheed. It dropped the lawsuit in 2015 after the Air Force agreed to open up competition.
The next year, SpaceX won an $83 million Air Force contract to launch the GPS III satellite, which will have a lifespan of 15 years.
The launch would be the first of 32 satellites in production by Lockheed under contracts worth a combined $12.6 billion for the Air Force GPS III program, Lockheed spokesman Chip Eschenfelder said.
Air Force spokesman William Russell said: "Once fully operational, this latest generation of GPS satellites will bring new capabilities to users, including three times greater accuracy and up to eight times the anti-jamming capabilities."
The launch was originally scheduled for 2014 but has been hobbled by production delays, the Air Force said.
It would mark SpaceX's first so-called National Security Space mission, as defined by the U.S. military, SpaceX said.The next GPS III satellite is due to launch in mid-2019, Eschenfelder said, while subsequent satellites undergo testing in the company's Colorado processing facility.