For around four years, Virgin Orbit has been busy developing a launch system to carry satellites into space using a rocket mounted to the wing of a modified 747. The team has today ticked off what it calls a significant milestone, carrying said rocket into the air and releasing it over the Californian desert for the first time.

Virgin Orbit plans to use this launch system to lift satellites that are as small as a loaf of bread or as big as a fridge into orbit, and touts a few benefits of this approach over traditional rockets that lift off vertically from a pad.

It is basically converting a modified 747 called Cosmic Girl into a rocket launcher, which will be able to take off from conventional airports. This means it will avoid bottlenecks at spaceports and be less susceptible to weather delays. The company says it will be able to deliver payloads to orbit at 24 hours notice, where current wait times can be up to 24 months.

Cosmic Girl with the LauncherOne rocket attached Virgin Orbit

This fully fledged service is still years away, but the company has been making some exciting progress in the last 12 months. Last September it showed off the Cosmic Girl mothership with special pylons fixed to the underside of the wing to carry its LauncherOne rocket, and then in November it started taking the booster along on test flights.

Today marks the first time that LauncherOne was released from Cosmic Girl mid-flight, completing the company's first ever "drop test." That means that the rocket was left to simply plummet back to Earth, with this first but critical test a way of making sure the release mechanisms work and can create a clean separation between the Cosmic Girl and LauncherOne.

When the time comes for the real deal, Cosmic Girl will release LauncherOne at an altitude of around 35,000 ft (10,700 m), at which point it will fire up its engines and blast the payload into space. Cosmic Girl, meanwhile, will come down to land like a regular 747 and prepare to go again.

Virgin Orbit is basically converting a modified 747 called Cosmic Girl into a rocket launcher, which will be able to take off from conventional airports Virgin Orbit

"What a moment, Virgin Orbit have released our fully built, full loaded LauncherOne rocket from Cosmic Girl for the first time," said Virgin CEO Richard Branson on Instagram. "Congratulations to all the team."

Virgin Orbit has said it hopes to launch commercial services in the UK by 2021.

Source: Virgin Orbit