BROOMFIELD, Colo. — A DARPA responsive launch competition that started two years ago came to an end March 2 without a winner as the sole remaining team was forced to scrub their final launch attempt less than a minute before liftoff.

Astra planned to launch its Rocket 3.0 vehicle from Pacific Spaceport Complex – Alaska on Kodiak Island as the first of two orbital launches for the DARPA Launch Challenge. However, controllers halted the countdown 53 seconds before a 3:55 p.m. Eastern liftoff because of guidance, navigation and control (GNC) data from the rocket described as “off-nominal.”

Astra had a launch window that was open through 6:30 p.m. Eastern, but about a half-hour before the window closed scrubbed the launch for the day, unable to resolve the GNC problem.

“We saw some data that concerned us and we decided it would be better to scrub the launch and try again another day, because if the data was correct, it could have definitely caused a problem with the flight,” said Chris Kemp, co-founder and chief executive of Astra, during the DARPA webcast of the launch attempt. “Winning the challenge would have been fantastic today, but our objective, really, is to reach orbit in as few flights as possible.”

Astra, in a statement posted to its website, said it would “plan to attempt another launch attempt as soon as possible,” but didn’t disclose a specific launch date.

Kemp said in a later call with reporters that the company was still diagnosing the root cause of the problem, and will also need to modify its launch license from the Federal Aviation Administration for a future launch not associated with the competition. The payload for the launch, a set of cubesats provided by DARPA, will be replaced by one of a “big line” of commercial customers willing to take a risk on an untried rocket.

“That is probably not a day or two. It’s more like a week or two,” he said of the timeframe of the next launch. “It’s certainly not a month or two.”

However, the scrub means the company is no longer eligible for up to $12 million in prizes from the DARPA Launch Challenge. Prior to the March 2 launch attempt DARPA announced this would be the final opportunity for the company to perform the first of two launches required by the competition. Astra had a two-week window to perform the launch, which was extended a day because of poor weather.

Had Astra reached orbit on this launch, it would have received $2 million. The company would have then attempted a second launch later in March, from a different pad at the same spaceport. If that launch was successful the company could have won $10 million.

Astra was one of three finalists announced in April 2019, a year after formally starting the competition. At the time, the company was only known as a “stealth” competitor and did not reveal its name and other details until a month ago.

The other two finalists dropped out of the competition last fall. Vector exited the competition in September because of financial difficulties that led to a bankruptcy filing, and Virgin Orbit left a month later so it could focus on other customers.

Todd Master, manager of the competition at DARPA, said on the webcast the company did achieve a lot in demonstrating it could set up on an unimproved launch site — a concrete slab — and be ready to launch in two weeks.

“It was a hard challenge,” he said. “They got almost there, almost made it to finish line. They just didn’t quite make it. But we learn a lot from these challenges and we think that even being able to get to the point we got to will demonstrate to folks that this is something that is right on the cusp of the possible.”

While the challenge is over, Master said on the later call with reporters that DARPA is looking at other ways of demonstrating responsive launch capabilities. One option in the “very, very early stages” of discussion is to incorporate a responsive launch into a military exercise, launching a satellite that would provide data to forces involved in that exercise. That effort, he said, would likely involve working with the U.S. Space Force and U.S. Space Command.

“Trying to pursue flexible and responsive launch is actually something DARPA’s been at for quite a while, and hasn’t quote gotten there yet,” he said, a reference to a number of vehicle development efforts sponsored by the agency that failed to reach orbit. “I think this is the among the closest that we’ve gotten.”