By Steven Siceloff
NASA’s Kennedy Space Center, Florida
A trio of NASA astronauts watched last Friday as engineers and technicians from Aerojet Rocketdyne fired one of the RL10 engines that will help power the first crewed flight test of Boeing’s CST-100 Starliner as it flies into orbit on a United Launch Alliance Atlas V rocket.
Steam billowed from the test stand in West Palm Beach, Florida, for about six minutes as the engine burned a combination of liquid hydrogen and liquid oxygen to produce some 22,300 pounds of thrust. Bolted into place inside a vacuum chamber, the engine was shut down and then re-ignited just as it will be when it is pushing a spacecraft into orbit.
“Today’s test was just amazing and from what it looked like, it looked flawless,” said astronaut Eric Boe, one of four NASA astronauts training to fly on the flight tests of the agency’s Commercial Crew Program missions. “They’ll pore through the data, but the cool part is that the next time that engine fires, it’s going to put one of us in space and we’re looking forward to it.”
After verifying the test was good and the information complete, Aerojet Rocketdyne will ship the same engine tested Friday to ULA’s Decatur, Alabama, plant where it will be bolted alongside an identical engine to the upper stage of an Atlas V booster for the crewed flight test. That stage, called Centaur, will take over once the first stage is spent and falls away during the climb into space. The Centaur will push the Starliner with astronauts inside to orbital velocity and put it on course to the International Space Station.
The engines for the first Starliner flight test – which will be flown without a crew aboard – have already been through acceptance testing including a similar engine firing and now are in different stages of processing at Aerojet Rocketdyne and ULA. Engines for future crew rotation missions to the station also are in various stages of production.
Although RL10s have been in use for more than 50 years and propelled NASA probes to distant worlds including the New Horizons spacecraft that surveyed Pluto for the first time last year, the engines have not been used on flights carrying people.
“The last thing for RL10s to do is put people into space,” said Matthew Bullivant, lead engineer for RL10 integration for Aerojet Rocketdyne.
RL10 engines also are slated for use on the Space Launch System rocket in development to lift astronauts to deep-space destinations aboard Orion spacecraft. A cluster of RL10s are to power the second stage of the Space Launch System booster during Exploration Mission 2 targeted to launch without a crew in 2018.
“My first impression was that everything was by the book and the team showed great attention to detail, which is what you have to do in this business, otherwise bad things happen,” said astronaut Barry “Butch” Wilmore. “Confidence comes in many ways, it’s meeting the people, it’s seeing the tests and there’s a lot of trust in a lot of the things we do.”
The test was a standard firing all engines go through before they are counted on to power a mission in flight. As the engine burned on the test stand, the teams watched from a control room a safe distance away, controlling the event remotely.
With four cameras transmitting from inside the vacuum chamber where the rocket fired, the astronauts and test crew watched icicles form on the rim of the rocket bell even as the fiery thrust burned less than an inch away. Frost even formed on the walls of the engine thanks to the super-cold hydrogen and oxygen propellants coursing through the engine’s turbopumps and plumbing. Frost doesn’t form on the engines in space since there is no moisture as there is in South Florida.
“You actually put it through more hoops than it probably will see in a launch, so you know that it will handle anything that happens on the way to space,” Boe said.
The engine test was the latest in a string of accomplishments for partners of NASA’s Commercial Crew Program. In Boeing’s development with ULA of the Starliner and Atlas V for human-rated spaceflight to the International Space Station, Boeing has rebuilt a former space shuttle processing facility into a factory for Starliners while ULA has added a Crew Access Tower to Space Launch Complex 41 so astronauts can get access to the spacecraft as it stands atop an Atlas V pointed to the sky on launch day.
Also in partnership with the Commercial Crew Program, SpaceX is developing its Crew Dragon spacecraft and Falcon 9 rocket to take astronauts to the station. Both companies are tailoring their spacecraft and launchers for missions to the space station. The new spaceflight capability will give the station the ability to support a resident crew of seven, meaning astronauts aboard the orbiting laboratory will have twice as much time to perform critical research on long-duration missions.
The engine firing capped a visit by the astronauts in which they saw the engine assembly work underway, toured company facilities and met the work force.
“When you go through the whole process, seeing the test and seeing the professionals out here building the engines, there was no doubt the test would be a success,” said Suni Williams, who also is training for Commercial Crew Program flight tests.
Engineers detailed specific elements of engine construction and showed the complex machinery involved with the work.
“This is what makes America great, and that’s why it’s so good to get out here and see things like this,” Boe said.