Virgin Orbit’s modified Boeing 747-400 jumbo jet, christened “Cosmic Girl,” is back at its home base in Long Beach, Calif., for preparations that will lead to its use as a launch platform for small satellites.

The jet returned to Long Beach on Monday after going through a series of inspections and modifications conducted in collaboration with L3 Platform Integration and VT Aerospace, two of Virgin Orbit’s partners.

In a news release, Virgin Orbit said the Federal Aviation Administration has issued Cosmic Girl an experimental airworthiness certificate, opening the way for flight tests to begin at California’s Mojave Air and Space Port.

“Virgin Orbit is in the home stretch of integrating our LauncherOne rocket and ground systems for launch and to support our customers’ missions,” said the company’s CEO, Dan Hart.

Virgin Orbit was spun off in March from Virgin Galactic, the space venture backed by British billionaire Richard Branson. Its mission is to send small satellites into orbit, using Cosmic Girl as a flying launch pad for LauncherOne.

The flight profile calls for Cosmic Girl to carry up rockets for release at an altitude of about 35,000 feet. Seconds after the release, the rocket would fire up its engine to put payloads weighing as much as 660 pounds into a 310-mile-high, sun-synchronous orbit.

The advantage of the air-launch system is that the 747 jet can take off from a wide variety of airports, adjust its flight plan to avoid unacceptable weather or range issues, and launch payloads into any desired orbital inclination.

Virgin Orbit already has a deal with OneWeb for 39 launches to help create a satellite constellation for global broadband internet service.

The company said the first LauncherOne flight is due to take place in the first half of 2018.