The culmination of three and a half years of work came roaring to life last week in the remote hills of Box Elder County.

Last Thursday, May 30, Northrop Grumman Corp. conducted the first test firing of the main motor for the OmegA rocket, a new launch vehicle designed to take satellites and other payloads for U.S. national security missions into space.

The Castor 600 motor, measuring 80 feet long and 12 feet in diameter, is the largest motor segment ever cast at the Promontory facility, which Northrop Grumman officially took over a year ago with its acquisition of Orbital ATK.

The motor tested last week is what will provide the thrust needed to boost the OmegA rocket beyond Earth’s gravitational pull. Witnesses to the static test firing, in which the motor was secured horizontally to the ground, saw 650,000 pounds of solid propellant fuel burned in just over two minutes, producing more than 2 million pounds of thrust.

An eager gathering of aerospace industry representatives, government officials, Northrop Grumman employees, curious members of the public and other observers let out a loud cheer immediately after the loud rumbling of the test subsided, and a billowing cloud of dense smoke lingered in the blue sky over the desert as the crowd dispersed.

The OmegA is being developed as the new launch vehicle for the U.S. Air Force, replacing the Atlas and Delta rockets. In October 2018, the Air Force awarded Northrop Grumman a $792 million contract to complete detailed design and verification of OmegA and launch sites.

Last week’s test verified the performance of the first-stage solid rocket motor for the intermediate version of OmegA, and keeps the vehicle on track to perform its first launch in 2021 and begin operational launches of national security payloads in 2022, according to Northrop Grumman officials.

John Slaughter, Northrop Grumman’s vice president of commercial propulsion system programs, said employees at Promontory and other company facilities have been working on the design, development and construction of the motor for the past three and a half years.

“It takes about that long, when you’re building the first one, to get it just right,” Slaughter said. “For those of us who build rocket motors, the best thing for us is to actually see it perform. We get to feel, hear and see the rocket motor.”

The motor tested last week is similar to the booster motors used for the now-retired space shuttle program, but is 12 feet longer and made of composite material that is lighter and stronger than previous versions, which were made of steel.

Kent Rominger, vice president of the OmegA program for Northrop Grumman, said afterward that the test was successful. Close-up video of the test shows what appears to be a small explosion toward the end of the firing that sent pieces of material flying, which Rominger acknowledged at a press conference following the test.

“It appears everything worked very, very well on this test,” Rominger said. “At the very end when the engine was tailing off, we observed the aft exit cone, maybe a portion of it, doing something a little strange that we need to look further into.”

Another test of the Castor 600 motor is planned for later this year in Promontory, most likely in September.

While last week’s test was performed with the motor heated to 90 degrees Fahrenheit prior to the firing, the motor will be cooled to around 40 degrees for the next one. It’s a common practice, and requirement, for new motors to be tested and qualified at both ends of the expected outdoor temperature range at which launches will take place (referred to as “hot” and “cold” tests) before an actual launch can happen.

Jennifer Bowman, communications director for Northrop Grumman’s Promontory facilities, said the motor will replace a Russian-built one. She said the U.S. Congress has issued a mandate to use American-made engines on national security missions.

“We’ve got a great offering for the Air Force,” Bowman said. “We’re ready to fly for them.”