ULA’s Atlas 5 rocket climbs off pad 41 with Boeing’s Starliner spacecraft. Credit: Alex Polimeni / Spaceflight Now
Boeing’s Starliner spacecraft thundered into orbit Thursday from Cape Canaveral aboard a United Launch Alliance Atlas 5 rocket, aiming to dock at the International Space Station on a years-late test flight to prove the capsule’s systems before flying astronauts.
The successful launch came nearly two-and-a-half years after the first Starliner test flight was cut short by software problems, preventing it from docking at the space station. Boeing and NASA decided to retry the test flight, but managers called off a launch attempt last August after valves in the Starliner propulsion system, requiring more than nine months of troubleshooting and testing to get the mission back on the launch pad.
Just like the first test flight in 2019, ULA’s Atlas 5 gave the Starliner spacecraft a good ride into space again Thursday, deploying the capsule on a planned trajectory just shy of the velocity needed to enter a stable orbit. The capsule fired thrusters to insert itself into a preliminary orbit about 31 minutes into the mission, officials said.
But engineers late Thursday were analyzing the failure of two thrusters during the orbit insertion burn. The Starliner’s orbital maneuvering and attitude control, or OMAC, jets were used for the injection burn, and will be fired again for several rendezvous burns to fine-tune the craft’s approach to the International Space Station.
“We had two thrusters fail,” said Mark Nappi, Boeing’s Starliner program manager. “The first one had fired. It fired for a second and then it shut down. The flight control system did what it was supposed to and it turned it over to the second thruster. It fired for about 25 seconds and then it shut down.
“Again, the flight control system took over, did what it was supposed to, and and went to third thruster and we had a successful orbital insertion,” Nappi said.
The Starliner spacecraft remained on course to dock at the space station around 7:10 p.m. EDT (2310 GMT) Friday, but officials said engineers will analyze the thruster issue overnight before a management meeting Friday morning to decide on whether to proceed with the approach to the station.
Steve Stich, NASA’s commercial crew program manager, said the spacecraft has “plenty of redundancy” to complete the test flight without the failed thrusters. The thrusters that shut off during the orbit insertion burn are located in one of four doghouse-shaped propulsion pods on the Starliner service module.
Each “doghouse” has three aft-facing OMAC engines, for a total of 12. There are eight additional OMAC engines positioned in other areas of the spacecraft. Each OMAC thruster generates about 1,500 pounds of thrust, and are used in conjunction with lower-thrust reaction control system thrusters to maneuver the Starliner spacecraft in orbit.
Liftoff of the United Launch Alliance Atlas 5 rocket, hauling Boeing’s Starliner crew capsule to space on a long-awaited demo flight before it’s cleared for astronaut missions.
The OMAC engines completed another orbit phasing burn Thursday night, and will be used again for approach maneuvers closer to the space station Friday. The capsule’s final approach will be controlled by the smaller reaction control system jets, then the OMAC engines will fire again at the end of the mission for the deorbit burn to set up the Starliner for re-entry and landing.
Despite the thruster problem, NASA and Boeing officials were pleased with the start to the Starliner’s unpiloted demonstration mission, known as Orbital Flight Test-2.
At the end of a smooth countdown, ULA’s Atlas 5 launcher ignited its Russian-made RD-180 main engine and two strap-on solid rocket boosters to climb away from pad 41 at Cape Canaveral Space Force Station at 6:54:47 p.m. EDT (2254:47 GMT).
The Atlas 5 steered northeast from Cape Canaveral to line up with the space station’s orbital plane. The RD-180 engine and twin booster rockets generated 1.6 million pounds of thrust, powering the Atlas 5 through a thin layer of high clouds.
The boosters burned out and jettisoned from the Atlas 5 core stage less than two-and-a-half minutes into the flight, then the RD-180 engine throttled down to limit g-loads on the Starliner spacecraft, a change to the Atlas 5’s flight profile to make for a more comfortable ride for astronauts.
The kerosene-fueled main engine shut off four-and-a-half minutes into the flight, and two hydrogen-burning RL10 engines lit on the Centaur upper stage for a seven-minute firing. The vehicle also shed a cover that protected the nose of the Starliner spacecraft during the climb through the atmosphere, and released an aerodynamic skirt under the capsule.
The Centaur stage shut down its engines 12 minutes into the flight, and the Starliner spacecraft deployed from the rocket nearly 15 minutes after liftoff. Starliner then primed its propulsion system for the orbit injection burn, and flight controllers at the Johnson Space Center in Houston took over the mission.
If all goes well, the capsule will complete a series of demonstrations to check out its pointing system and navigation sensors before moving in for the final phase of the rendezvous with the station.
An RD-180 main engine and two AJ-60A solid rocket boosters power the Atlas 5 launcher off pad 41 with Boeing’s Starliner spacecraft. Credit: Michael Cain / Spaceflight Now / Coldlife Photography
Starliner will reach a position about 82o feet (250 meters) from the station around 5:46 p.m. EDT (2146 GMT). At that time, Starliner should have established a communications link with the space station, allowing the astronauts inside the research complex to send commands to the approaching capsule.
The station astronauts will send a command for the Starliner to hold its approach. They could also command Starliner to retreat away from the space station in the event of a problem, but that’s not part of the demonstrations planned Friday.
“This being a test flight, we’ve got to demonstrate all the new technologies that Boeing has put into their spacecraft, and confirm that they all work as expected,” said Emily Nelson, NASA’s acting chief flight director at Johnson. “Most of those demonstrations are tied to first establishing one sensor that can be trusted, and then comparing the next sensor to that first sensor, and so on through the rendezvous period.
“One of the most important and really cool sensors they have on their spacecraft is called VESTA, and it basically looks at the silhouette of the space station, and once we can confirm that it’s seeing the space station correctly, it’s identifying where it ought to go,” Nelson said. “The space station is really large, we’d like for it to arrive at the correct port.
“Once we can identify it’s going to the right place, we’ll do a couple of demonstrations once we get close in, where the spacecraft will stop to demonstrate that if we tell it to stop, it will, in fact, stop,” Nelson said.
Then the Starliner will move in for an automated link-up with the forward port of the space station’s Harmony module, 90 degrees from Harmony’s top-facing port, where a SpaceX Dragon crew capsule is docked.
While the Starliner capsule is docked at the station, the crew on the research complex will open hatches and enter the Starliner crew cabin for additional tests and inspection. Astronauts Kjell Lindgren and Bob Hines will perform voice communications checks with a headset in the Starliner crew cabin.
For the OFT-2 mission, Boeing placed an instrumented test dummy in the Starliner commander’s seat to gather data on the environments astronauts will see on future missions. The mannequin, named “Rosie” after the World War II icon Rosie the Riveter, wears a blue Boeing spacesuit.
The station astronauts will also unpack about 500 pounds (227 kilograms) of cargo inside the capsule, and replace it with cargo tagged for return to Earth.
The Starliner will undock from the space station no earlier than May 25 for return to Earth, targeting a parachute-assisted, airbag-cushioned landing at White Sands Space Harbor in New Mexico.
NASA and Boeing engineers will evaluate the results from the OFT-2 mission before approving the launch of the Crew Flight Test, the first Starliner mission with astronauts on-board.
Officials said before the OFT-2 launch that Boeing aims to have the next crew capsule ready for flight by the end of the year, but managers won’t commit to a launch schedule until they evaluate the results of the unpiloted demo mission.
“We wouldn’t be here right now if we weren’t confident that this would be a successful mission,” said Butch Wilmore, one of a group of NASA astronauts assigned to the Starliner program, in a press conference before the OFT-2 launch. “But there are always unknown unknowns. That’s what historically has always gotten us. It’s those things that we don’t know about and we don’t expect.”
Boeing’s Starliner crew capsule is one of two human-rated spaceships NASA selected in 2014 to ferry astronauts to and from the International Space Station. The other spacecraft, SpaceX’s Dragon capsule, began flying astronauts in 2020 and has now launched seven crew missions.
NASA has funneled more than $5 billion into Boeing’s Starliner crew capsule program since 2010. Boeing took a $595 million charge to pay for delays, and the new OFT-2 test mission, following the problem-plagued Starliner test flight in 2019.
After OFT-2, and following a test flight with astronauts, NASA plans to certify the Starliner spacecraft for regular crew rotation missions to the space station. The agency plans to alternate between the Starliner and Dragon spacecraft, providing “dissimilar redundancy” for crew access to the station.
“We’re going to be focused on this mission, the flight test objectives, as well as getting ready for the flight test objectives for the Crew Flight Test, which has a goal of certification at the end, so that we as NASA can have regularly-scheduled dissimilar redundant flights to the International Space Station,” said Mike Fincke, another NASA astronaut following the Starliner program. “So we can go up, one flight with Boeing, one flight with SpaceX.”
Follow Stephen Clark on Twitter: .