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A faulty booster valve derailed the first crewed launch of a Boeing Starliner spacecraft

A faulty booster valve derailed the first crewed launch of a Boeing Starliner spacecraft

Atlas 5 missile Carrying astronauts The explosion was first fueled Monday night to boost it Boeing’s long-awaited Starliner crew ferry ship Into orbit on its first test flight. But a problem with a valve on the rocket’s upper stage forced mission managers to request a cleanout just two hours before liftoff.

It was a frustrating disappointment for the leader Barry “Butch” Wilmore and co-pilot Sunita Williams, who were in the process of preparing for launch when the scrub was announced. This moment brought to mind one of Wilmore’s favorite sayings: “You’d rather be on Earth wishing you were in space than in space wishing you were on Earth.”

NASA said in a blog post early Tuesday that the launch would be postponed until at least Friday “to complete data analysis on the pressure-regulating valve in the liquid oxygen tank of the Atlas 54 Centaur rocket’s upper stage and determine whether it is necessary to replace the valve.” valve.”

If the analysis concludes it is safe to launch Atlas 5 as is, NASA, Boeing and United Launch Alliance, the Atlas 5 maker, could recycle for a second attempt at 9 p.m. EDT on Friday. If the valve has to be replaced, the rocket will have to be returned to ULA’s Vertical Integration Facility for repairs, delaying another launch attempt until Sunday or later next week.

The debate revolves around how often the pressure relief valve in question opens and closes rapidly, as it attempts to stabilize itself, causing a hum that sound engineers can hear at the launch pad. Similar behavior has been observed in the past, and engineers have a workaround that will usually fix the problem.

A view of an Atlas 5 rocket and Starliner crew capsule moments after the launch countdown was canceled due to problems with the upper stage oxygen relief valve. The launch is now on hold pending resolution of the valve issue.


“What you’ll typically do is activate the solenoid that forces the valve to close, which will spin the valve, if you will… and it almost always stops,” said Tory Bruno, CEO of United Launch Alliance. “Once the crew got out, we turned the valve, and it stopped buzzing.

“If this was a (launch) satellite, that’s our standard procedure, and the satellite would already be in orbit. But that changes the status of the fueled Centaur, and we don’t do that when people are present. And so the flight rules called for us to clean up and get the crew out before we We turn that valve.”

The valve, used to maintain the proper pressure inside the Centaur stage’s liquid oxygen tank, is qualified for 200,000 open and close cycles, Bruno said.

The valve doesn’t have any sensors to directly measure those cycles, but engineers planned to work through the night analyzing accelerometer data from sensors mounted on the Centaur stage’s two RL10A rocket engines to determine how often and whether the valve actually opened and closed. no. You are close to or past the qualifying threshold by launch time.

If the valve turns out to still have life, ULA may be able to move forward for another test launch on Friday night. If the mechanism has to be replaced, the Atlas 5 will have to be returned to its processing hangar for repairs, delaying another launch attempt until at least Sunday or later next week.

Sunita Williams, left, and Commander Butch Wilmore exited the Starliner capsule shortly after the launch was aborted and were returned to crew headquarters at Kennedy Space Center to relax and await word on when they might be allowed to attempt another launch.


“I promised Butch and Sonny a boring evening,” Bruno said at a press conference. “I didn’t mean for it to be so boring, but we’ll follow our rules and make sure the crew is safe.”

Starliner, which is several years behind schedule and more than $1 billion over budget, is Boeing’s answer to SpaceX’s Crew Dragon, an already operational spacecraft that has carried 50 astronauts, cosmonauts and civilians into orbit in 13 flights, 12 of which to the station Satellite.

NASA funded the development of both spacecraft to ensure that the agency would be able to launch crews to the outpost even if one company’s ferry ship was grounded for any reason. While Boeing took longer than expected to prepare its ship for crew flights, all systems appear to be ready for launch from pad 41 at Cape Canaveral Space Force Station at 10:34 p.m. EDT.

Engineers were in the process of completing loading the propellant when the valve problem was discovered. After evaluating its performance, engineers were “uncomfortable” with its behavior and the launch was cancelled.

Wearing dark blue Boeing pressure suits, Wilmore and Williams, two veteran Navy test pilots and active-duty astronauts, began untying the straps to exit the Starliner and wait for word when they would get another shot at launch.

The Atlas 5 rocket, which is making its 100th flight, is an extremely reliable rocket with a perfect launch record. The rocket is equipped with a sophisticated emergency fault detection system, and the Starliner, like SpaceX’s Crew Dragon, features a “full envelope” abort system capable of quickly propelling the capsule away from its booster in the event of a major malfunction at any point in the rocket. Launch pad into orbit.

When it lifts off, the Atlas 5 will need just 15 minutes to propel the Starliner vehicle into a primary orbit. Once in space, the astronauts will then monitor the firing of two fast engines to adjust the ship’s orbit before taking turns testing the spacecraft’s computer-aided manual control system.

As with any other space station rendezvous, the Starliner will approach the laboratory from behind and below, turn to a point just ahead of the forward station and then move to dock at the forward port of the Harmony module

During final approach, Willmore and Williams will again test the capsule’s manual controls, to ensure that future crews can adjust the trajectory or direction of the spacecraft at their discretion if necessary.

The Starliner is also equipped with a fully manual backup system that allows the crew to directly control the ship’s thrusters using a joystick-like hand controller, bypassing the spacecraft’s flight computers. Willmore and Williams will test this system after leaving the station around May 15 to begin the journey back to Earth.

Starliner pilot Barry “Butch” Wilmore and co-pilot Sunita Williams, both veteran Navy test pilots and NASA astronauts with four spaceflights between them.


Once docked, Willmore and Williams will spend just over a week with the station’s seven long-term crew members: astronauts Oleg Kononenko, Nikolai Chub and Alexander Grebenkin, along with NASA’s Matthew Dominik, Michael Barratt, Janet Epps and Tracy Dyson.

If the Starliner test flight goes well, NASA managers expect to certify it for routine crew rotation flights, launching one Crew Dragon and one Starliner each year to deliver long-term crew members to the station for six-month tours of duty.

“A very crucial teacher”

Jim Frey, NASA’s associate administrator for space operations, called the Starliner crew flight test, or CFT, a “very, very important milestone.”

“Let me remind everyone again, this is a new spacecraft,” he told reporters last week. “We certainly have some unknowns in this mission, and we may encounter things we don’t expect. But our job now is to remain vigilant and keep looking for problems.”

While he said he was confident the Starliner was up to the task, Frye said he didn’t want to “push too far” because the crew had yet to complete a successful mission. “But when we do, and when we certify Starliner, the United States will have two unique human transportation vehicles that provide critical redundancy to reach the International Space Station,” he added.

But it wasn’t easy.

Following the retirement of the Space Shuttle in 2011, NASA awarded two Commercial Crew Program contracts in 2014, one to SpaceX for $2.6 billion and one to Boeing for $4.2 billion, to stimulate the development of autonomous spacecraft capable of carrying astronauts to and from the International Space Station. .

The target date for CCP’s initial flights was 2017. A lack of funding in Congress and technical hurdles delayed development, including an explosion during a ground test that destroyed the SpaceX Crew Dragon vehicle.

But the California rocket builder finally began crewed flights in May 2020, successfully launching two NASA astronauts on a Crew Dragon test flight to the space station.

Since then, SpaceX has launched eight operational crew rotation flights to the station, and three research missions to the laboratory funded by the Houston company. Axiom Space And a Purely commercial, a flight for two men and two women into low Earth orbit paid for by billionaire pilot and businessman Jared Isaacman. In all, 50 people flew into orbit aboard Crew Dragons.

It was a different story for the Boeing Starliner.

During an initial unmanned test flight in December 2019, a software error prevented the ship’s flight computer from loading the correct launch time from its counterpart aboard the Atlas 5.

The Starliner capsule and its service module were attached to the thinner Centaur upper stage of the Atlas 5 booster for launch. The cylinder-shaped extension at the bottom of the service module is an “air skirt” designed to improve aerodynamics during exit from the thick lower atmosphere.

United Launch Alliance

As a result, the burn required for orbit insertion did not occur on time, and due to unrelated communications problems, flight controllers were unable to regain control in time to proceed with the space station rendezvous.

Software issues were addressed after the Starliner’s landing, along with a variety of other issues that came to light in the post-flight review. Boeing elected to conduct a second test flight, at its own expense, but the company encountered stuck propulsion system valves in the Starliner’s service module. Engineers were unable to solve the problem and the capsule was removed from Atlas 5 and returned to its processing facility for troubleshooting.

Ultimately, engineers attributed the problem to moisture, presumably caused by high humidity and heavy rain after being rolled out on the pad, which reacted chemically with the propellant to form corrosion. Corrosion prevents valves from opening on command.

To clear the way for launch the following May, valves in the new service module were replaced and the system was modified to prevent water from leaking onto the launch pad. The Starliner’s second test flight in May 2022 was a success, docking at the space station as planned and returning to Earth with a precision landing.

But in the aftermath of the flight, engineers discovered new problems: a problem with the parachute harness connectors and concerns about the protective tape wrapped around the wires that could catch fire in the event of a short circuit.

Work to correct these issues pushed the first crewed flight from 2023 to 2024. When all was said and done, Boeing spent more than $1 billion of its own money to pay for additional test flights and corrective actions.

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