Three teams have qualified to go into the rocket-launching phase of the DARPA Launch Challenge: Vector Launch, Virgin Orbit’s VOX Space subsidiary … and a team to be named later.

In making today’s announcement, DARPA said the third team asked to stay anonymous for a few months more, for competitive reasons. That mystery team will come out of stealth in advance of the fly-off, which has been shifted to take place early 2020.

Like previous DARPA competitions, the Launch Challenge is meant to boost commercial innovation in a technological area of interest to the military — in this case, rapid and flexible launch capabilities.

Here’s how the challenge works: DARPA will ask the three competitors to launch payloads to low-Earth orbit from two different U.S. locations within a matter of weeks. Teams will receive notice of the first launch site a few weeks prior to launch, and they’ll find out the exact details surrounding the payload and intended orbit just days before launch.

More than 50 teams signed up to take part in the DARPA launch challenge, but the three finalists were able to complete the entire qualification process, including the acceptance of a launch license application to the Federal Aviation Administration. In recognition of their achievements so far, each qualifying team is getting $400,000 of DARPA’s money.

There’s much more money to be won: Teams will receive a $2 million prize for successfully delivering payloads to orbit in the first launch. And if the teams execute successful second launches, they could win prizes of $10 million, $9 million and $8 million, which would be doled out to finishers based on factors including mass, time to orbit and orbit accuracy.

From DARPA’s perspective, it’s worth dangling millions of dollars in prizes to encourage launch providers to make their systems more flexible

“There’s a real benefit to making use of something already in development in the commercial market, and offering incentives to modify systems and approaches to favor responsiveness and flexibility versus just favoring high cadence for commercial customers,” Todd Master, the challenge’s program manager in DARPA’s Tactical Technology Office, said in a news release.

Master explained that the current routine for launching military and government payloads requires years of advance planning and large, fixed infrastructure. “We want to move to a more risk-accepting philosophy and a much faster pace so we can put assets into space at the speed of warfighter needs,” he said.

Virgin Orbit and its wholly owned VOX Space subsidiary are working on a system that calls for sending satellites to orbit on Virgin’s LauncherOne rocket, which is air-launched from a modified Boeing 747 jet. The air-launch system makes it possible to take off from any base that has a suitable runway, and fly around unacceptable weather if necessary to send payloads into a wide range of orbits.

Vector Launch is working on a rapid-deployment rocket known as the Vector-R that can be sent into a variety of orbits from a mobile transporter/launcher.

And the stealth team? Here’s as much as DARPA is willing to say: “They have been quietly working to dramatically improve access to space for small spacecraft. They have asked to remain undisclosed for now, but look forward to revealing more about their rocket, team and capabilities in the period leading up to the DARPA Launch Challenge.”