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United Launch Alliance’s first Vulcan Centaur rocket completed a crucial test of its Blue Origin-built BE-4 main engines Wednesday night, clearing one of two remaining technical hurdles before the launch pad can be cleared for its inaugural flight later this year.

The two engines of the BE-4 Vulcan rocket ignited at 9:05 p.m. EDT Wednesday (0105 UTC Thursday) and burned for about six seconds, generating nearly a million pounds of thrust as stabilization restrictions kept the launcher firmly in place. Starting blocks at platform 41.

“This is a huge milestone,” said Mark Piller, ULA’s vice president for the Vulcan Missile Program. “This is as close as you can get to launching a missile without actually launching the missile, so the full integrated test of all the airborne components, the ground systems, all coming together, putting it into everything we do on a typical launch day, including actually starting the main engine Everything is short of a missile launch.

Piller called the flight-ready launch “our last major milestone on the launch path” for the first Vulcan Centaur rocket.

ULA’s launch team loaded methane, liquid hydrogen, and liquid oxygen thrusters into the Vulcan first stage and Centaur upper stage Wednesday afternoon, then stopped the countdown clock for several hours to allow engineers to assess whether a lightning strike near the launch pad affected any critical systems. . .

After the launch team’s final readiness reconnaissance, the countdown resumed from a fuse hold at T-7 minutes and the Vulcan Centaur rocket turned on internal power and the propellant tanks rose to flight pressure before opening the valves to allow methane and liquid oxygen to flow into the BE-4’s engine thrust chambers. .

The start-up sequence for the twin engines started at T-minus 5 seconds. The engines throttled to about 60% power for two seconds, then the missile’s flight computer ordered the BE-4s to throttle before turning the engines off. The test launch sent a plume of exhaust from the east-facing trench flame at Platform 41.

“Nominal run!” Tory Bruno, CEO of ULA, tweeted.

The two BE-4 engines for the Vulcan rocket were built by Blue Origin, which was founded by billionaire Jeff Bezos. Blue Origin plans to use an array of seven BE-4 engines on its New Glenn rocket, which is still in an early stage of development.

“There is nothing sweeter in rocket science than the noun,” Bezos tweeted Wednesday night. “Congratulations to you, Tori, and the entire team!”

Technicians at ULA rolled a Vulcan Centaur rocket from its hangar to Pad 41 Tuesday at Space Force Station Cape Canaveral in preparation for a launch test.

The launch of the readiness to fly was the culmination of a series of tests and countdown exercises at Cape Canaveral to prepare for Vulcan’s first test flight. Recently, ULA’s launch team loaded methane, liquid hydrogen, and liquid oxygen thrusters into the Vulcan booster and Centaur upper stage during a tank test on May 12.

ULA moved the Vulcan Centaur missile to the Vertical Integration Facility after the tank test on May 12 for “modifications” to the vehicle. Changes included adjusting the setting with ground hydraulic pressure, changing the liquid oxygen occupation rate, and altering the purge and cooling gas flow to the BE-4 engine’s ignition, according to Tory Bruno, ULA CEO.

With these changes complete, ground teams planned to conduct a flight readiness launch on May 25, but ULA postponed the test firing after discovering a problem with the BE-4’s engine ignition system. That sent the rocket back into the hangar for troubleshooting before ULA returned the Vulcan launcher to pad 41 on Tuesday.

ULA says it has installed additional hardware on the rocket to monitor the performance of the engines during launch readiness to fly. Engineers will spend the next several weeks analyzing data from test firings to make sure everything works as designed.

However, the launch schedule for Vulcan Centaur’s maiden voyage remains unclear.

ULA said it is more than 98% complete of the Vulcan rocket qualification program, with incomplete work related to the final ground test of the Vulcan Centaur rocket’s upper stage. A hydrogen explosion in March interrupted a structural test of Vulcan’s Centaur upper stage at NASA’s Marshall Space Flight Center in Huntsville, Alabama.

The explosion damaged the test stand and the Centaur upper stage test article. The Vulcan rocket uses a larger, upgraded model of the Centaur upper stage currently flying on ULA’s Atlas V rocket.

If engineers decide they don’t need to make any changes to the Centaur upper stage on the first Vulcan rocket, the test flight could take off this summer. In remarks last month, Bruno said the mission could be delayed until later this year if corrective actions are needed on Centaurs.

“Pending data review and investigation results, we will develop a launch plan,” ULA said in a statement Wednesday evening. “Testing is an integral part of the launch vehicle development program, and we will fly when we believe it is safe to launch.”

ULA is a 50-50 joint venture between Lockheed Martin and Boeing, and merged the Atlas and Delta missile programs in 2006. The Vulcan missile will fly in several configurations, with varying numbers of mounted solid rocket boosters of various sizes available. On each flight, depending on mission requirements.

The Vulcan rocket on the program’s first test flight features a colorful livery with bright red flames emblazoned on the side of the 17.7-foot (5.4-meter) first stage. For tank tests and readiness to fly launches, the Vulcan is not fitted with any solid rocket boosters or payload fairings. In this configuration, the vehicle is approximately 166 feet (50.7 m) tall.

With the launch test complete, ULA planned to drain the rockets’ fuel tanks and return the Vulcan Centaur to its hangar for inspections. Technicians may need to adjust or replace the thermal blankets around the engines that would have been fired by the test firing. ULA will also swap disposable ignition devices on the BE-4 engines before moving forward with final launch preparations.

The inaugural flight of the Vulcan rocket will be the first launch to use Blue Origin’s new methane-fueled BE-4 engines. At full throttle, each BE-4 engine can generate approximately 550,000 pounds of thrust. Two of them will power each Vulcan core stage, with zero, two, four, or six solid rocket boosters to add thrust for the first two minutes of flight.

Ground teams will install two solid-fuel boosters from Northrop Grumman and a payload shroud provided by Beyond Gravity, formerly Ruag Space.

The upper stage of Vulcan’s Centaur rocket, called Centaur 5, is an upgrade of the upper stages currently flying on ULA’s Atlas V rocket. The Centaur 5 features a wider diameter to accommodate larger cryogenic hydrogen and oxygen fuel tanks, along with two Aerojet Rocketdyne RL10 engines. Centaurs flying on an Atlas V rocket usually fly with a single engine.

Once all Vulcan missile configurations are operational, the new missile will replace and increase the lift capacity currently provided by all ULA missiles. The largest variant of the Vulcan rocket, with a single primary stage and upgraded upper-stage engines that will begin flying in the next few years, will have a greater payload-lift capacity than ULA’s Delta-4-Heavy, which has three liquid-fuel first-stage boosters connected together. some. .

The Vulcan Centaur with upgraded upper stage engines will be capable of lifting a payload of up to 60,000 pounds (27.2 metric tons) to low Earth orbit.

Ultimately, ULA plans to recover reused BE-4 engines from Vulcan launches, but not the entire first stage.

ULA unveiled the Vulcan rocket in 2015, then targeted the first launch of the new vehicle in 2019. The company selected the Blue Origin BE-4 engine for its first-stage propulsion system in 2018. At that time, ULA aimed to launch its first Vulcan test flight in 2020.

But delays, caused primarily by problems discovered in the production and testing of the BE-4 engine, forced the first Vulcan test flight to be pushed back by several years. Bruno said earlier this month that Blue Origin and ULA completed final qualification testing of the BE-4 engine before the first Vulcan launch, clearing a hurdle that still threatens to delay the Vulcan’s debut earlier this year.

On its maiden voyage, the Vulcan rocket will launch a commercial lunar lander developed by Astrobotics, which will attempt to deliver a suite of NASA experiments and technical experimental payloads to the lunar surface. The Astrobotic probe, named Peregrine, is part of NASA’s Lunar Commercial Payload Services program, which purchases flights to the moon for the agency’s payloads on commercially owned spacecraft.

Two prototype Amazon Kuiper broadband satellites will also be launched aboard the first Vulcan launch.

The US Space Force has selected the ULA Vulcan rocket to launch the majority of the Army’s large national security satellites over the next five years. The Army requires “two certified flights” for a Vulcan missile before it can be approved for national security launch missions.

A second Vulcan test flight is scheduled for early 2024 using Sierra Space’s Dream Chaser spaceplane, a new resupply vehicle for the International Space Station. This will be followed by the launch of the first Vulcan missile carrying a national security military payload.

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