Tech billionaire Elon Musk's SpaceX has successfully launched its first US national security satellite in its bid to break into the lucrative market.
A SpaceX rocket carrying a US military navigation satellite has blasted off from Florida's Cape Canaveral, marking the space transportation company's first national security space mission for the US.
The Falcon 9 rocket carrying a roughly $US500 million ($A711 million) GPS satellite built by Lockheed Martin lifted off from Cape Canaveral at 8.51am local time on Sunday.
Four previous scheduled launches in the past week, including one on Saturday, were cancelled because of weather and technical issues.
The successful launch is a significant victory for billionaire Elon Musk's privately held rocket company, which has spent years trying to break into the lucrative market for military space launches dominated by Lockheed and Boeing.
SpaceX sued the US Air Force in 2014 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 $US83 million Air Force contract to launch the GPS III satellite, which will have a lifespan of 15 years.
The satellite is the first to launch out of 32 in production by Lockheed under contracts worth a combined $US12.6 billion for the Air Force GPS III program, according to Lockheed spokesman Chip Eschenfelder.
The launch was originally scheduled for 2014 but has been hobbled by production delays, the Air Force 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.