An Atlas 5 rocket boosted a Boeing Starliner crew capsule into orbit Thursday for a make-or-break unpiloted test flight, the company third attempt in two-and-a-half years to reach the International Space Station.
The Starliner’s debut test flight in December 2019 was spoiled by embarrassing software glitches that prevented an autonomous rendezvous and docking with the space station. An attempted reflight last August was called off when corrosion was found in critical propulsion system valves.
But with a long list of upgrades and improvements in place, mission managers were confident the spacecraft was finally ready for another attempt and at 6:54 pm EDT, the capsule’s United Launch Alliance Atlas 5 roared to life and vaulted away from launch pad 41 at the Cape Canaveral Space Force Station.
Fifteen minutes later, after a picture-perfect climb to space, the Starliner was released to fly on its own. Sixteen minutes after that, the spacecraft carried out a 45-second thruster firing to put itself in an initial orbit, on course for rendezvous with the International Space Station.
That firing happened at the wrong time during the Starliner’s initial test flight in 2019, but it went off without a hitch Thursday in the flight’s first post-launch hurdle.
If all goes well, the capsule will catch up with the lab complex late Friday afternoon, using a high-tech artificial vision system to home in for docking around 7:10 pm On board: about 500 pounds of station crew supplies and equipment and an instrumented mannequin – Rosie the Rocketeer – that will collect environmental data throughout the mission.
The flight plan calls for the capsule to spend five days attached to the station before returning to a White Sands, New Mexico, landing on May 25. Assuming no major problems, Boeing and NASA hope to launch an astronaut crew to the station on a piloted test flight before the end of the year.
The test flight is a critical step towards that goal, one NASA has been working for since 2014.
To make up for the space shuttle retirement in 2011, NASA has financed the development of commercially procured astronaut ferry ships, awarding Boeing a $ 4.2 billion contract to develop the Starliner while SpaceX won a $ 2.6 billion contract to develop the company Crew Dragon.
NASA’s goal was to re-establish a US human space launch capability and end the agency’s post-shuttle reliance on Russian Soyuz spacecraft for transportation to and from the space station.
Both companies had initial problems, but SpaceX was able to stage a successful unpiloted test flight to the lab complex in early 2019, followed by six crewed station missions and one privately chartered space tourism flight.
Boeing has had a rougher time of it, failing to get its Starliner to the space station as planned during the 2019 test flight and then running into the valve corrosion issue that derailed a launch attempt last August.
NASA managers are anxious to get the Starliner in operation as soon as possible to provide assured access to space if technical problems force either company to stand down at some point.
“We can’t have all of our eggs in one basket,” veteran astronaut Mike Fincke, who’s trained to fly aboard a Starliner, said in an interview with CBS News.
“Something could go on with SpaceX, they could have a glitch with a Falcon 9, they’re launching them all the time, and that could delay us … getting back and forth to the International Space Station.”
Having a second provider, he said, “gives us a robust capability so if one isn’t working, we’ve got the other one.”
The Starliner’s long-awaited reflight began with the ground-shaking start up of the Atlas 5’s Russian-built RD-180 main engine, generating 860,200 pounds of thrust, followed an instant later by ignition of two strap-on solid-fuel boosters, adding another 697,000 pounds of push.
The 172-foot-tall rocket majestically climbed away atop a brilliant stream of fiery exhaust, arcing to the northeast to climb directly into the plane of the International Space Station’s orbit.
The two strap-on boosters were jettisoned about two minutes and 20 seconds after liftoff and the RD-180 shut down two minutes later after boosting the rocket out of the dense lower atmosphere. The Centaur second stage, powered by twin Aerojet Rocketdyne RL10A engines, then completed the climb to space.
The Starliner was released to fly on its own 15 minutes after takeoff. Boeing and ULA designed a unique trajectory for the Starliner, one that sets up a quick return to Earth if major problems develop. To reach a stable orbit, the spacecraft had to execute an orbit insertion rocket firing 16 minutes after reaching space.
During the Starliner’s maiden launch December 19, 2019, a software error prevented the ship’s flight computer from loading the correct launch time from its counterpart aboard the Atlas 5. As a result, the orbit insertion burn did not happen on time and because of unrelated communications issues, flight controllers were unable to regain control in time to press ahead with a space station rendezvous.
The software problems were addressed after the Starliner’s landing, along with a variety of other issues that came to light in a post-flight review. Boeing opted to carry out a second test flight, at its own expense, but the vehicle was not ready to fly again until last August.
Then, during the countdown, launch controllers ran into stuck propulsion system valves in the Starliner’s service module. Engineers were unable to resolve the problem and the capsule was taken off its Atlas 5 and hauled back to its processing facility for troubleshooting.
Engineers eventually traced the problem to moisture, presumably from high humidity and torrential rain after rollout to the pad, that chemically reacted with thruster propellant to form corrosion. The corrosion prevented the valves from opening on command.
To clear the way for Thursday’s launch, the valves in a new service module were replaced. Gaseous nitrogen was used to purge the thruster pods and keep them dry, seals were added where wiring enters the thruster housings, further isolating the hardware, and the valves were regularly opened and closed to verify performance.
Assuming the reflight goes well and Boeing completes a piloted test flight to the station without any major problems, NASA managers want to rotate crews to and from the station with one flight each year by SpaceX and one by Boeing.
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