NASA Marshall Space Flight Center logo.
Jan. 25, 2021
When the big ring of nine Merlin engines on the Falcon 9 rocket rumbled to life, propelling NASA’s SpaceX Crew-1 spacecraft and its occupants to their historic rendezvous with the International Space Station, most spectators were watching for the customary bloom of smoke and fire.
NASA manager Steve Gaddis and his team were also listening, anticipating the musical sound of success. At 7:27 p.m. EST on Nov. 15, 2020, they heard it.
SpaceX and NASA test engineers at the agency’s Marshall Space Flight Center in Huntsville, Alabama, spent months reviewing data from Merlin engine tests performed at the SpaceX test facility in McGregor, Texas, prior to delivery to NASA’s Kennedy Space Center in Florida for the launch. It’s teamwork Marshall knows well; workers here developed the most powerful engines ever built, from the Apollo and space shuttle eras through today’s mighty Space Launch System engines.
Image above: NASA’s SpaceX Crew-1 mission launches Nov. 15, 2020, on a Falcon 9 rocket powered by nine Merlin ID engines. The Crew Dragon spacecraft’s delivery of its astronaut crew to the International Space Station was the first executed under NASA’s Commercial Crew Program, which will regularly fly crew and cargo to the orbiting science facility while NASA focuses on robust, new missions to the Moon, Mars and beyond. Image Credits: NASA/Joel Kowsky.
“We have insight into the qualification and critical design reviews for all elements, components, and subsystems of the engines our commercial partners use to propel their rockets,” said Gaddis, the center’s lead for NASA’s Commercial Crew Program and deputy manager at Marshall for the program’s Launch Vehicle Systems Office.
He compared the task to a symphony orchestra rehearsing for a big performance. Each test engineer on the team is a virtuoso, he suggested, a subject-matter expert – and mastering a new engine is like playing a new work by a master composer.
“We have the A-team here, from our vehicle and systems engineers to subject-matter experts in turbopump design, rotordynamics, thrust vector controls, computational fluid dynamics, structural resonance and flow-induced vibration, materials and processes, the whole nine yards,” he said.
But it’s not enough to perform flawlessly in one’s own area; each contributor has to play in sync with all the rest – an added feat in the midst of accomplishing tasks remotely during a pandemic. That harmonious approach is the cornerstone of Marshall’s engineering success.
“Testing is rigorous, integrated, and holistic,” Gaddis said. “Our team identifies even the most minute performance concerns and brings recommended safety and reliability solutions back to the whole SpaceX and NASA team.”
Even small changes to one component can have ripple effects, fundamentally changing design and safety specifications across the entire engine. Change one note, after all, and the whole composition has to be reconsidered.
“Everyone plays their part,” said Mark Darden, an engineer who specializes in rotordynamic analysis at Marshall. “The main thing is we’re all mindful that our particular space, our area of performance, is not necessarily the most important space. The work, when it’s most successful, is a grand compromise, a give-and-take approach to find balance and achieve the desired outcome. That’s the mark of a great collective effort.”
It all comes down to vibration and stability. “Most car engines weigh 1,000 pounds and deliver 400-500 horsepower,” Darden said. “The space shuttle main engine weighed about the same – but delivered on the order of 70,000 horsepower. These are high power density, massively intricate machines, each with precise vibration characteristics.”
Image above: Working from his home office, Steve Gaddis, deputy manager of Marshall’s Launch Vehicle Systems Office, supports NASA’s Commercial Crew Program as it successfully begins the job of delivering astronauts and cargo to the International Space Station. Image Credits: NASA/Steve Gaddis.
His fellow Marshall dynamics engineer Tony Fiorucci agreed. “A typical car engine’s crankshaft rotates typically at 1,500 to 2,000 revolutions per minute, or rpm,” Fiorucci said. “The rotating shaft in Merlin’s turbopump spins at roughly 30,000 rpm. Even the slightest imbalance or vibration outside margins can be catastrophic, hence the rigor of testing and analysis.”
It is fitting that such checkout work is performed at Marshall. At the turn of the century, engine designers at Marshall sought to deliver Fastrac, a streamlined, innovative turbopump rocket engine that would offer NASA and its partners an alternative to the space shuttle main engine, then the workhorse of the agency’s shuttle fleet. The Fastrac program was shuttered in 2001, but SpaceX leveraged much of the design and technology to aid development of its original Merlin 1A engine.
Darden and Fiorucci, colleagues for more than three decades at Marshall, are quick to note they stand on the shoulders of giants – building on decades of engine test data and analytical techniques from the Saturn V’s F-1 engines, the RS-25s that powered the shuttle, and countless unique engine development efforts along the way.
“By building and maintaining this data across decades, we’ve banked a long history of criteria, strategy, and proven methodologies,” Fiorucci said. “Since we began partnering with SpaceX, we’ve added hundreds more SpaceX engine tests to our database, refining our expertise, expanding our catalog of success – and continuing our consistent build methodology reaching back to the earliest days of U.S. rocket engine development.”
“It’s exhilarating to be on this team, working with some of the best in the business to resume the rhythm of American flights supporting station crew rotation,” Gaddis said.
His team felt that thrill again during the symphony of Crew-1’s thunderous engines – a fanfare for uncommon men and women of talent, vision and meticulous skill.
“Music to our ears,” he added.
More about the Merlin and Crew-1 mission
Developed by SpaceX for its Falcon series of launch vehicles, the Merlin 1D first stage engine uses kerosene and liquid oxygen as fuel and incorporates a pintle injector first used in the Apollo-era Lunar Module landing engine. For NASA’s Crew-1 mission, the Dragon spacecraft, christened Resilience, employed a nine-engine configuration that collectively delivered roughly 1.7 million pounds of thrust at launch.
NASA’s SpaceX Crew-1 mission delivered to orbit NASA astronauts Michael Hopkins, Victor Glover, and Shannon Walker, and Japan Aerospace Exploration Agency mission specialist Soichi Noguchi. They rendezvoused with the International Space Station on Nov. 16, 2020, to join the Expedition 64 crew: Commander Sergey Ryzhikov and flight engineer Sergey Kud-Sverchkov of the Russian space agency Roscosmos, and American astronaut Kate Rubins.
More about NASA’s Commercial Crew Program
NASA’s Commercial Crew Program is a partnership between the nation’s space agency and industry partners across the country, working jointly to develop and fly new generations of human space transportation systems to extend humanity’s reach into the solar system, pursue new science and discovery missions, and forge a path back to the moon and on to Mars. Learn more here:
https://www.nasa.gov/exploration/commercial/crew/index.html
Related links:
Commercial Crew Program: https://www.nasa.gov/exploration/commercial/crew/index.html
Fastrac: https://www.nasa.gov/centers/marshall/news/background/facts/fastrac.html
International Space Station (ISS): https://www.nasa.gov/mission_pages/station/main/index.html
Marshall Space Flight Center: https://www.nasa.gov/centers/marshall/home/index.html
Images (mentioned), Text, Credits: NASA/Lee Mohon/Marshall Space Flight Center/Janet Anderson.
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