Richard Branson's Virgin Orbit is set to launch the first orbital rocket from UK soil on Monday. Watch live as the rocket drops from a Boeing 747.

• Richard Branson's Virgin Orbit is set to launch the first orbital space rocket from British soil.
• Virgin Orbit CEO Dan Hart said the crew will proceed cautiously in case winds or lightning set in.

Virgin Orbit, founded by Richard Branson, is about to launch the UK's first orbital space mission, making history for the country's aerospace industry.

After several delays, Virgin Orbit was given the green light on December 21 to launch its "Start Me Up" satellite mission from Spaceport Cornwall at Cornwall Airport Newquay in southern England. Virgin Orbit has scheduled the launch for Monday, January 9.

At a press conference on Sunday at the spaceport, which Insider attended, Virgin Orbit CEO Dan Hart said the rocket had already been armed and was going to be filled with fuel later in the day.

"We're in different airspace than we've flown before. Our pilots are ready," he said, warning that Virgin Orbit will proceed cautiously, especially if winds, lightning, or other bad weather conditions approach around the launch window.

Start Me Up marks some major milestones, including Virgin Orbit's first international mission, the first horizontal launch in Western Europe, and the UK's first satellite launch and first orbital space mission from British ground.

Livestream: Watch Virgin Orbit's Cosmic Girl take off and release the rocket

Watch the historical rocket launch live on Virgin Orbit's YouTube livestream below, starting at 4:30 p.m. ET Monday.

The rocket launch will lift off horizontally, in comparison with other space missions that launch vertically, such as those operated by SpaceX and Blue Origin.

Cosmic Girl, a repurposed Virgin Atlantic Boeing 747-400 aircraft, is expected to take off from Spaceport Cornwall between 5:16 p.m. ET and 6:16 p.m. ET with the LauncherOne rocket underneath its left wing. When the plane climbs to an altitude of 35,000 feet — around 40 minutes after taking off — the pilot will press a button that releases the 70-foot-long, two-stage rocket into the air.

Cosmic Girl is projected to return to the Spaceport one hour later, according to Virgin Orbit's plans. Meanwhile, LaucherOne will accelerate skywards before the first stage separates from the second stage. Once the second stage reaches low-Earth orbit, it will release a batch of nine satellites.

Once all the satellites are delivered, the second stage will fall back down to Earth and burn up in the atmosphere.

UK aims to be a 'science superpower'

Overall, this will be Virgin Orbit's sixth mission. The company called the mission "Start Me Up" in tribute to The Rolling Stones, a famous British rock band.

During the press conference, Melissa Thorpe, head of Spaceport Cornwall, said: "I cannot wait for the UK to join that exclusive launch club."

In response to Insider's question about where the Start Me Up mission positions the UK in the space industry, Ian Annett, deputy chief executive of the country's space agency, said it "allows us to grow so we can achieve being that science superpower."