Updated 9:20 p.m. Eastern Oct. 24 revising the launch record of Astra Space.

WASHINGTON — A three-way launch contest is now down to one unidentified company after two competitors backed out, the U.S. Defense Advanced Research Projects Agency said Oct. 22.

DARPA said its Tactical Technology Office will continue the challenge early next year even though Vector and Virgin Orbit subsidiary Vox Space reversed course, electing not to participate. DARPA selected those two companies, as well as a “stealth” competitor, in April as finalists from a field of dozens of applicants.

“As indicated in the quickly narrowing field of competitors, responsive and flexible access to space remains a significant challenge,” Todd Master, program manager for the DARPA Launch Challenge, said in an agency news release. “Future warfighting needs will require true space resilience, the ability to put assets into orbit quickly and from a variety of locations. It’s a fundamental shift from a strategic use of exquisite space assets to a more tactical future.”

DARPA said Vox Space, which markets Virgin Orbit’s LauncherOne air-launched rocket to military customers, withdrew from the challenge this month so that Virgin Orbit can “focus on its upcoming commercial launches.”

In an Oct. 22 statement, Virgin Orbit said it supported the aims of the competition to demonstrate responsive launch. “However, after comparing DARPA’s requested timeline with our commitments to our commercial and government customers, we have elected to withdraw from the competition,” the company said.

Company sources, speaking on background, said the decision was a financial one. The company would have made less on launches being performed for the competition than those under contract to existing customers. There was also the risk of delaying or losing a customer in order to meet the short timeframes mandated by the competition to carry out a launch.

Vector withdrew in September because of financial problems, DARPA said. Vector announced Aug. 9 it was suspending operations because of what it called “a significant change in financing,” although a small team remains in place to continue work on its Vector-R rocket.

The lone contender in the DARPA Launch Challenge is a “space startup comprising industry veterans currently operating in stealth mode,” DARPA said. That company, believed to be Astra Space, as the company identifies itself in Federal Aviation Administration licenses, is working toward internal technical milestones, DARPA said. Astra Space conducted two suborbital launches in 2018 from Kodiak, Alaska, both of which were categorized as mishaps by the FAA.

Launch startup Aevum, which received Vector’s ASLON-45 launch contract from the Air Force in September, is not the stealth company, CEO Jay Skylus told SpaceNews.

In a statement to SpaceNews, Master said there were no plans to reopen the competition despite the loss of two of its three finalists selected in April. “Small launch is an emerging industry and we timed the Challenge to influence developing systems toward responsive, flexible launch to meet national security needs,” he said. “The Challenge’s goals are a high bar, but If even one team makes it to launch day within weeks of notification, with minimal infrastructure, the Challenge will be a success.”

The DARPA Launch Challenge will require the stealth company to conduct two launches weeks apart from two different launch sites, with just 30 days notice which spaceport will be first.

DARPA is offering a $2 million prize for completing the first launch, and a $10 million prize for the second launch. The stealth company will have to succeed in its first launch to qualify for the second. DARPA said the first launch is planned for February 2020, with the second a month later. The agency has arranged the payloads for both missions to low Earth orbit.

The launch sites in play for the contest are Vandenberg Air Force Base in California, the Pacific Spaceport Complex in Alaska, Wallops Flight Facility on Wallops Island, Virginia, and the U.S. Navy’s Outlying Field on San Nicolas Island in California.

Jeff Foust contributed to this article.