Cosmic Girl, the specially modified aircraft that Virgin Orbit engineers designed to essentially function as a flying launchpad, is scheduled to make its first landing at Long Beach Airport on Monday.

The aircraft is a former Virgin Atlantic 747-400 passenger jet with modifications enabling it to fire a rocket that Virgin Orbit calls LauncherOne. The idea is for Cosmic Girl to be able to carry LauncherOne under one if its wings and fire the rocket spaceward like a giant missile.

Cosmic Girl underwent its modifications in Texas. Virgin Orbit has more than 300 people attached to its LauncherOne project working in Long Beach.

Although Virgin Orbit Vice President of Special Projects Will Pomerantz kept details about Monday’s event and the project’s future close to the vest, he said: “The whole timing of this event is more about an emotional milestone as much as a technical milestone.”

Virgin Orbit split from Virgin Galactic to become its own company in early March. Virgin Galactic’s focus will be offering commercial human flights into space, while Virgin Orbit’s business model is based on launching small satellites into orbit.

The new company’s headquarters and LauncherOne assembly facility are part of the Douglas Park complex, which is a cluster of industrial and commercial developments in northeast Long Beach built on land where Douglas Aircraft Co. and Boeing Co. crews once assembled such historic aircraft as the DC-3 and the B-17 bomber. Generations of workers went on to manufacture a succession of postwar jets there, but that work concluded after Boeing shut down production of the 717 passenger jet in 2006.

Ending 717 production in Long Beach was an epochal business decision on the part of Boeing executives, as it closed the book on the production of large passenger jets in California. Nearly a decade later, Boeing closed its assembly plant for the C-17 Globemaster III military cargo jet. The facility was in operation near Long Beach Airport before the final C-17 flew away in late 2015.

“It’s not lost on any of us when we drive into work, we’re driving past the DC Jets sign and the C-17 hangar,” Pomerantz said.

Virgin Orbit’s executives are planning for the company to occupy a different niche in the private spaceflight industry than that of Space Exploration Technologies Corp., the Hawthorne company that’s popularly known as SpaceX.

SpaceX’s Falcon 9 rocket is designed to be a launch vehicle, with a reusable first stage, that can carry a heavy payload to geostationary transfer orbit. At geostationary orbit, a satellite is in motion at the same velocity as the earth’s rotation at a point more than 22,000 miles above the Earth’s surface at the equator, according to NASA.

A recent example of the kind of mission SpaceX participates in is the July 5 launch of Intelsat 35e, a seven-ton communications satellite for Intelsat. The Luxembourg-headquartered company has a sales office in Long Beach.

SpaceX advertises a $62 million price for a 2018 Falcon 9 launch.

By contrast, Virgin Orbit customers may pay a price in the $10 million to $12 million range for satellites to hitch a ride on board a LauncherOne vehicle. The company’s advertised specs for LauncherOne describe a spacecraft capable of carrying a payload roughly 1,100 pounds into low-Earth orbits nearly 125 miles above the planet’s surface.

A large number of scientific and weather satellites operate at this level, according to NASA.

Cosmic Girl is expected to fly over LGB shortly after 4 p.m. Monday.

Virgin Orbit leaders plan for Cosmic Girl’s main launch site to be Mojave Air & Space Port, which is northwest of Edwards Air Force Base in Kern County.