Baku, August 15, AZERTAC

A shuttle-era main engine roared to life in a ground-shaking Mississippi test firing Thursday, the latest in a series of full-duration burns to make sure the upgraded powerplants can handle the higher temperatures, pressures and thrust levels needed for the agency’s new Space Launch System — SLS — super rocket, according to Cyberwardesk.

Bolted into the Apollo-era A-1 test stand at NASA’s Stennis Space Center near Bay St. Louis, Miss., RS-25 engine No. 0525 ignited at 5:01 p.m. EDT, throttling up with a 120-decibel roar as it gulped more than 300 gallons of liquid oxygen and hydrogen rocket fuel per second.

With the propellants burning at some 6,000 degrees Fahrenheit — hot enough to melt lead — the Aerojet Rocketdyne engine’s exhaust plums shot out its liquid hydrogen-cooled nozzle at 13 times the speed of sound, blasting a billowing cloud of white steam high into the sky above the test stand.

Six seconds after ignition, the engine’s new flight computer was programmed to command valve settings that increased the thrust level to 109 percent of the power originally intended for shuttle launchings. The test plan called for the thrust level to drop to around 80 percent before eventually throttling back up above 90 percent.

Unlike an actual launch, where the sound quickly fades away as the rocket climbs away toward space, the RS-25 test firing went on for a full eight minutes and 55 seconds — the time needed for the new SLS rocket to reach orbit — before the engine finally shut down, putting on a memorable show for reporters and a throng of social media representatives.

“No exaggeration to say you feel it more than hear it,” said Stephen Clark, a reporter for Spaceflightnow.com. “And hearing protection is actually needed.”

Steve Swofford, NASA’s SLS engines manager, said telemetry indicated “the initial results are great. We ran full duration for 535 seconds, we met our test objectives, didn’t note any anomalies at this time. So now we get the fun part of going through the data.”

Once known as the space shuttle main engine, or SSME, the compact powerplants flew three at a time aboard NASA’s winged orbiters, along with a pair of four-segment solid-fuel boosters that provided the lion’s share of the initial push out of the deep lower atmosphere.

For NASA’s gargantuan 322-foot-tall Space Launch System booster, needed for eventual piloted flights into deep space, two more powerful five-segment boosters will be used, along with four renamed RS-25 engines.