After Vulcan comes online, ULA plans to dramatically increase launch cadence

The idea was to push the qualification engines through their paces, and beyond their expected flight environment, to find any flaws. During this series of tests, Bruno said, the oxygen pump on one of these engines has consistently produced about 5 percent more oxygen into the engine than expected. This fell outside the bounds of nominal performance but had only been observed in this engine.

"We've arrived at the conclusion that this is simply likely unit-to-unit variation," Bruno said. "The other engines, including the flight engines that are on rocket right now, are all very similar, and of that earlier family that did not have an extra 5 percent of output coming out of the main oxygen pump. Now we're satisfied, and we'll resume testing shortly with the other engine. That testing sequence will run about six weeks."

May the 4th be with you

With this schedule in mind, Bruno said the Vulcan rocket already at Cape Canaveral in Florida could theoretically complete its pre-launch testing and be ready to fly by mid-April. However, because the "Cert-1" mission's primary payload is a lunar lander built by Astrobotic, there are only certain launch windows available to synch up the launch with the Moon. Therefore, he said, United Launch Alliance is targeting a four-day window that will open on May 4.

Bruno said he is confident that the Cert-1 mission's three payloads, including Astrobotic's spacecraft, two Project Kuiper satellites for Amazon, and a memorial for Celestis, will be ready by then. (Ars is less confident in the readiness of Astrobotic's Peregrine lander, which has yet to have its engines installed.) Bruno said he always has "backup plans for his backup plans" in case the payloads are not ready by May, but he does not expect to need them.

After the Cert-1 mission, ULA expects to fly a second certification mission later this year for Sierra Space, sending its Dream Chaser spacecraft on a test flight. It is unclear whether Dream Chaser will be ready for this flight either. Regardless, Bruno is pushing to fly two missions by the fall of 2023 so he can complete the military's certification process and conduct Vulcan's first national defense mission for the US Space Force during the fourth quarter of 2023. He did not specify what payload that would be.

Between its commitment to fly 60 percent of the Space Force's missions in the next few years, and dozens of launches for Amazon's Project Kuiper megaconstellation, Vulcan has a lengthy manifest through the mid-2020s. Bruno said that, in addition to flying out its remaining Atlas V rockets, ULA plans to meet that demand.

That’s a lot of Vulcans

"We have to ramp up," Bruno said. "Before the end of 2025 we expect to be really at a tempo, which is flying a couple of times a month, every two weeks."

This would be a cadence unprecedented in the history of United Launch Alliance, even during its heyday of flying Atlas and several variants of the Delta rocket. However, Bruno said the company is making the investments needed in launch sites in Florida and California, as well as production factories, to meet this demand.

For now, ULA's focus is on scaling up Vulcan flight rates. That means that the company's goal of reusing the BE-4 engines on its rocket—the plan is to separate the engine section, and capture the engines with a helicopter as they descend to Earth—will take a backseat for now.

"In terms of our engine recovery, that is going to happen within a handful of years," Bruno said. "I don't want to say exactly when because it's part of the contract we have with one of our customers at this time, and we're not releasing the details of that. But it will take a couple of years to actually be reusing the engine."

Last November, as a rideshare on an Atlas V launch, NASA tested a demonstrator of an inflatable aeroshell, or heat shield, that could slow down and survive atmospheric re-entry. ULA plans to adapt this technology, developed by NASA for interplanetary missions, as part of its engine recovery plans.

"You will see us potentially do more demonstrations," Bruno said. "We'll be collecting environmental data to see booster experiences. We'll recover engines and look at them. And then eventually we'll have the confidence to recover them, inspect them, and then reuse them. And so that will happen in this window of a few years, but it's too early at this moment for me to say exactly when. But you'll see that activity ramp up."