Bloomberg -- Elon Musk’s Space Exploration Technologies Corp. capped a record-setting year Sunday when it launched a rocket carrying a new GPS III satellite for the U.S. Air Force, after delaying the mission several times because of a technical issue involving its rocket sensors and bad weather.

The Falcon 9 rocket lifted off from Cape Canaveral Air Force Station in Florida at 8:51 a.m. local time carrying the Lockheed Martin-built satellite. SpaceX first won U.S. Air Force certification for national-security space missions in spring 2015, breaking the lock on sensitive satellite launches long held by United Launch Alliance, a joint venture between Boeing Co. and Lockheed Martin Corp. The GPS III will go into medium Earth orbit roughly 1 hour and 56 minutes after liftoff, according to the SpaceX press kit.

This was SpaceX’s 21st launch of the year, up from a record 18 in 2017. The company has been able to cut costs and win market share by designing its rockets for reusability. This time, however, SpaceX won’t attempt to land Falcon 9’s first stage after the launch, the company said in its press kit, citing mission requirements.

ULA has flown eight missions in 2018, and a ninth is scheduled for no earlier than December 30 from Vandenberg Air Force Base on California’s central coast.

“SpaceX has had a phenomenal year no matter how you slice it,” Luigi Peluso, an aerospace and defense consultant at AlixPartners, said in a phone interview. “In 2019, the big race is who is going to be the first company to put humans into space and bring them back. You’ve got SpaceX, Boeing, Virgin Galactic and Blue Origin all vying.”

SpaceX, along with Boeing, has a contract to ferry American astronauts to the International Space Station as part of what’s known as the Commercial Crew program with NASA, but the timeline for the first flights has slipped repeatedly. The agency’s current schedule has SpaceX’s first uncrewed demonstration flight January 17 and its first flight with astronauts on board in June.

Hawthorne, California-based SpaceX’s valuation has climbed as it has racked up successful missions, making it the third-most valuable venture-backed startup in the U.S. after Uber Technologies Inc. and Airbnb Inc. The Wall Street Journal reported Tuesday that SpaceX is poised to raise another US$500 million by selling stock at a US$30.5 billion valuation, citing people familiar with the transaction.