SpaceX finally launched the secretive Zuma spacecraft for the US government on Sunday night (8 January) after multiple delays from the Cape Canaveral Air Force Station in Florida. The mission marked the first Falcon 9 launch for SpaceX of 2018 following a record year in 2017 that saw 18 successful launches.

The Falcon 9 booster's two stages separated a little over two minutes into the flight with the second stage carrying the mysterious Zuma to low-Earth orbit. The spacecraft's exact location has not been disclosed.

Meanwhile, the rocket's first stage made its way back to Earth and aced the landing at SpaceX's Landing Zone 1 at Cape Canaveral less than eight minutes after liftoff.

The booster landing marked SpaceX's 21st successful landing so far - now its signature move.

Details about the US government's mysterious satellite and its function are classified. Due to its secretive nature, SpaceX did not live stream the entire mission.

In November, Northrop Grumman - the Virginia-based aerospace and defence company that built the Zuma spacecraft - said in a statement: "The US government assigned Northrop Grumman the responsibility of acquiring launch services for this mission. Northrop Grumman realises this is a monumental responsibility and we have taken great care to ensure the most affordable and lowest risk scenario for Zuma."

The Zuma launch was initially scheduled for liftoff in November but was delayed numerous times due to faring issues and weather delays. Last week, SpaceX said both its rocket and the payload were "healthy" and ready for liftoff.

This year, SpaceX aims to top last year's record of 18 successful launches and no failures.

"We will increase our cadence next year about 50 percent," SpaceX president and COO Gwynne Shotwell told Space Newsin November. "We'll fly more next year than this year, knock on wood, and I think we will probably level out at about that rate, 30 to 40 per year."

The successful Zuma mission also clears the path for the launch of SpaceX's new massive Falcon Heavy rocket later this month. Falcon Heavy will have three times the thrust of the Falcon 9 and is designed to eventually carry humans into space and one day fly crewed missions to the Moon or Mars.

The company has yet to set a date for its inaugural launch. However, CEO Elon Musk said last week that they intend to launch by the end of January carrying his cherry-red Tesla roadster into space.

He has warned multiple times that the Falcon Heavy may not succeed in its first launch attempt since there are elements of its operation that are difficult to test on the ground.

"It's guaranteed to be exciting," Musk said.

SpaceX lifted a secret payload for the US government over the weekend SpaceX