Virgin Orbit captive carry
Virgin Orbit's "Cosmic Girl" 747 aircraft, with a LauncherOne rocket attached, performs a final captive carry flight April 12 before the company's first orbital launch attempt. Credit: Virgin Orbit

WASHINGTON — Virgin Orbit announced May 20 it will make the first flight of its LauncherOne air-launched vehicle as soon as May 24, but is setting modest expectations about the probability of success.

The company said in a statement that it current plans to perform its inaugural LauncherOne mission May 24, with “Cosmic Girl,” the company’s modified Boeing 747, flying out of the Mojave Air and Space Port in California. A four-hour launch window starts at 1 p.m. Eastern. The company has reserved a backup launch date for May 25, during the same four-hour window.

About 50 minutes after takeoff from Mojave, flying near the Channel Islands off the California coast, Cosmic Girl will release the LauncherOne rocket attached to its left wing. Five seconds later, the rocket will ignite the NewtonThree engine powering its first stage for a three-minute burn.

At the end of the burn, the first stage will separate and the smaller NewtonFour engine powering its second stage will ignite for six minutes, with the rocket’s payload fairing separating about 20 seconds into the burn. After shutdown, the rocket will coast for 22 minutes before firing the NewtonFour again for 15 seconds and then releasing its payload into low Earth orbit.

The company is not planning to livestream the launch, and will not be hosting press in Mojave because of restrictions imposed by the coronavirus pandemic. Instead, it will provide updates on social media.

Virgin Orbit emphasized that the mission is a test flight, and that previous launch vehicles have only had about a 50% success rate on their first launches. The launch is carrying what the company is only describing as a “test payload” that would be remain in orbit only a short time even if the launch is a success.

“We’ll continue the mission for as long as we can. The longer LauncherOne flies, the more data we’ll be able to collect,” the company said. “Should we defy the historical odds and become one of those exceedingly rare teams to complete a mission on first attempt, we will deploy a test payload into an orbit, take our data, and then quickly de-orbit so as not to clutter the heavens.”

The company has tested all aspects of the system separately, including a drop test of a LauncherOne test article in July 2019 and a captive carry test flight April 12 where the rocket used for this mission was loaded with cryogenic propellants and flown over the drop zone in the Pacific, but not released. However, this will be the first time the company will attempt igniting the rocket engines in midair.

Virgin Orbit said that, should the test launch be a success, it will move into operational missions, starting with one for NASA’s Venture Class Launch Services program carrying a collection of smallsats. The next LauncherOne rocket is nearing completion at the company’s factory in Long Beach, California, but the company didn’t offer an estimate of when it would be ready for launch.

Virgin Orbit also announced May 7 plans to begin launches from Andersen Air Force Base in Guam, a location that allows the company to support launches to both equatorial and polar orbits. The first LauncherOne mission from Guam will be for the Defense Department’s Space Test Program, designated STP-27VP, but no date is set for its launch yet.

Jeff Foust writes about space policy, commercial space, and related topics for SpaceNews. He earned a Ph.D. in planetary sciences from the Massachusetts Institute of Technology and a bachelor’s degree with honors in geophysics and planetary science...