Raumfahrt+Astronomie-Blog von CENAP - Blog: Raumfahrt - Boeing confident in achieving six flights to the ISS despite Starliner delay

Montag, 14. August 2023 - 07:04

Raumfahrt - Boeing confident in achieving six flights to the ISS despite Starliner delay

14.08.2023

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Boeing’s Starliner Crewed Flight Test (CFT) which will carry astronauts Barry “Butch” Wilmore and Sunita “Suni” Williams to the International Space Station (ISS) is now delayed to next year, with the earliest chance for launch in March. However, Boeing is still confident it will complete the six crewed flights ordered by NASA despite the planned demise of the ISS in 2030. NASA and Boeing shared the updated launch information in a press briefing on Monday, Aug. 7.

The Crew Space Transportation-100 (CST-100) Starliner was supposed to launch its first crewed flight on July 21, but Boeing found several issues that could have posed a threat to the safety of the astronauts, such as flammable tape and weak parachute soft links, causing yet another mission delay.

Boeing’s CST-100 Starliner, along with SpaceX’s Crew Dragon, is part of NASA’s Commercial Crew Transportation Capability (CCtCap), which aims to have two vehicles carry American astronauts and cargo to the ISS on rotation throughout the year, with the “goal of ending the nation’s sole reliance on Russia,” according to the space agency. The companies were selected in 2014 for the contract, and while SpaceX has almost completed seven crewed trips to the Station, Boeing’s Starliner has been plagued with delays spanning years.

Earliest CFT launch in March 2024

Opening the briefing, Mark Nappi, vice president and program manager of the CST-100 Starliner at Boeing, said the teams planned to have the spacecraft ready by early March. “That does not mean we have a launch date in early March, that means that we are ready with the spacecraft then, and we’re now working with the NASA Commercial Crew program, ISS, and ULA [United Launch Alliance] on potential launch dates based on our readiness,” Nappi added.

The pushback for launching the spacecraft was due to numerous reasons, but primarily the error with the soft links and the tape. Amid final certifications ahead of the original July 21 launch, the review found that teams had incorrectly gathered data on the strength of the lanyards — or soft links — that are used to connect the spacecraft and the parachutes. The fabric joints of the parachute suspension lines did not meet the required failure load limits and were therefore not strong enough.

At the time, the soft links were tested again and Nappi had said: “Sure enough, they did fail at the lower limit, and that ended up decreasing our factor of safety in the soft link pretty significantly.”

The parachutes are integral to getting the crew safely out of a dangerous situation for low-altitude abort use. The service module of Starliner contains four launch abort engines that would fire between three and 5.5 seconds during the abort procedure, with enough thrust to maneuver the spacecraft away from the rocket before splashing down in the ocean under parachutes.

However, according to Steve Stich, the manager of NASA’s Commercial Crew Program, the team “has made a tremendous amount of progress” since the last media briefing in June. Boeing and its suppliers have redesigned the soft links and are in the middle of testing, Stich added.

“They had a very productive technical interchange meeting in early July with the supplier, and not only did they redesign that particular joint but also went through and looked at all the rest of the areas on the main canopies… and didn’t really find any other areas where we had a joint that was improperly designed. So, they went through and did a thorough review of the entire parachute system to make sure we didn’t have any other areas that we would have a concern about,” Stich explained.

Another major discovery for Boeing and NASA in June was that the P-213 tape used on Starliner wrapped around wiring harnesses was flammable and needed immediate replacing. The tape is to protect the wiring from potential abrasions or nicks.

“This is a tape that’s widely used across the aerospace industry for many applications for protecting wires from abrasion. I would say in the NASA database the entries were a bit inconsistent relative to the flammability of that tape at various levels of oxygen concentration. And so, it was a bit confusing as to when it could be used and when it couldn’t,” Stich said.

Stich explained Boeing has “worked very hard” on the tape, and teams have removed a substantial amount of it from the spacecraft. “They’ve broken the spacecraft into two areas, what’s called the upper dome in the crew module and the lower dome beneath the floor, and they’ve remediated about 85% of the tape in the upper dome and have removed a substantial number of pounds of the tape actually from the vehicle, and also developed a few techniques to mitigate propagations should anything happen,” Stich added.

Will the six flights NASA ordered be jeopardized by delays?

Boeing’s Starliner program has been in development for over ten years. In 2010, the aerospace company announced it was manufacturing the Boeing CST-100 under NASA’s Commercial Crew Development Space Act Agreement. At the time, Boeing said the spacecraft would be operational by 2015. Then in September 2014, NASA selected Boeing and SpaceX for the CCtCap contracts. Under the contract, Boeing received $4.2 billion, and SpaceX received $2.6 billion.

The vehicle can carry seven passengers for missions to low-Earth orbit, and for NASA missions to the ISS, Starliner can accommodate four crew members plus cargo. The spacecraft is reusable up to ten times, with a six-month turnaround time, and is built to launch atop of United Launch Alliance (ULA) Atlas V rocket.

Since inking the contract, NASA ordered six flights for Boeing to operate to the ISS. But the ongoing delays on top of the Station’s likely demise from 2030 have put the plan into question. However, in the press briefing, Nappi asserted there is “no reason to change our plans with the six flights, plus CST fits well into the window that we have, and there are additional flights that are available outside of those six with other customers, so I think we are still committed like we have been in the past.”

Further, Stich added: “Our plan all along has been to have two different, unique, and diverse space transportation systems. We’re working hard to get that in place. Once we do that, [and] get Boeing through the crewed flight test and then certification work for the vehicle, the plan would be to fly one Boeing flight and then one SpaceX flight for our crew rotations per year. And then if you just kind of look at taking us through the end of ISS, I mean, we’ve got plenty of flights for Boeing to go fly and we’re in good shape.”

Progress so far

After years of development, the company finally attempted the Boeing Starliner Orbital Flight Test (Boe-OFT) launch toward the ISS on Dec. 20, 2019. However, the excitement was short-lived after an anomaly with Starliner’s mission elapsed timeclock early into the flight caused the spacecraft to burn a significantly larger amount of propellant than planned, enter an incorrect orbit, and therefore never reach the Station. What was supposed to be an eight-day mission docked to the ISS became a two-day mission, seeing Starliner land at the White Sands Space Harbour on Dec. 22, 2019.

More than two years later on May 19, 2022, the uncrewed Orbital Test Flight-2 Starliner flight launched atop an Atlas V N22 toward the ISS. The spacecraft was cleared to journey to the Station after entering into the correct orbit with its OMACS thrusters, unlike the 2019 flight. Starliner successfully docked on the forward port of the Harmony (Node 2) module at the Pressurized Mating Adapter-2 (PMA-2) on May 20, while the Expedition 67 crew planned to open the hatch the next day.

The spacecraft carried five hundred pounds of cargo containing mostly food and other items. After completing several scientific objectives, such as testing Starliner’s quiescent mode, the spacecraft undocked from the ISS on May 25, reentered the Earth’s atmosphere near Baja California, and touched down at White Sands in New Mexico.

In July, Boeing announced the Starliner program had suffered a loss of $257 million during a quarterly earnings update, bringing the total loss to more than $1.1 billion for the company. While this is a steep loss for Boeing, the company is under a fixed-price contract with NASA, meaning the agency is not responsible for the associated costs of the delays.

Quelle: NSF

Raumfahrt - Boeing confident in achieving six flights to the ISS despite Starliner delay

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