Tag: ISS

According to an article today at Ars Technica, there are indications that NASA will not buy any further flights of Boeing’s Starliner capsule after it finally completes its present three-launch contract.

NASA hasn’t decided if it will require Boeing to launch another test flight before formally certifying Starliner for operational missions. If Starliner performs flawlessly after undocking and successfully lands this weekend, perhaps NASA engineers can convince themselves Starliner is good to go for crew rotation flights once Boeing resolves the thruster problems and helium leaks.

In any event, the schedule for launching an operational Starliner crew flight in less than a year seems improbable. Aside from the decision on another test flight, the agency also must decide whether it will order any more operational Starliner missions from Boeing. These “post-certification missions” will transport crews of four astronauts between Earth and the ISS, orbiting roughly 260 miles (420 kilometers) above the planet.

NASA has only given Boeing the “Authority To Proceed” for three of its six potential operational Starliner missions.

Apparently NASA has not decided whether to commit to any more Starliner operational manned flights behind those first three.

There are obvious good reasons for NASA’s hesitancy, most of which center on Boeing and its inability to get Starliner flying without technical problems. One that isn’t as obvious however is ISS itself. Boeing has taken so long in getting Starliner flying that the end of ISS in 2030 is now looming. There are only so many manned flights that NASA needs to buy before the station is decommissioned. Afterward the agency will still need to hire ferrying services to the new privately owned stations, but it is too far in the future to consider either SpaceX or Boeing for those decisions.

Starliner docked to ISS.

In a briefing today, NASA’s administrator Bill Nelson announced that Boeing’s Starliner capsule, launched in June on its first manned mission, will return unmanned and that the two astronauts it brought to ISS — Butch Wilmore and Suni Williams — will return in February 2025 as part of the crew of the next Dragon manned mission, scheduled to launch in late September.

Nelson made it a point to note that NASA’s past inactions to protect astronauts on two different shuttle missions, thus leading to their deaths, was a factor in this decision. The agency now decided safety must come first, and since Starliner’s return abilities still carry uncertainties that relate directly to safety, it decided to use a more reliable and tested Dragon capsule to return those astronauts back to Earth. During the entire briefing and Q&A session it became very clear that NASA is now paying very close attention to its engineers and their conclusions, rather than dismissing those conclusions because of other management concerns, as it did during those previous two shuttle failures.

Nelson also stated that NASA still wants to use Starliner as a second crew vehicle to ISS. He noted that he has spoken to Boeing’s new CEO, who apparently committed to getting Starliner fixed and operating. It remains undecided whether another test manned flight will be required of Boeing (at Boeing’s cost) before NASA certifies it as an operational vehicle. Whether any other customers will be willing to use the capsule remains unlikely until Boeing has flown a lot of Starliner NASA flights with no problems.

At this moment they are looking to bring Starliner back in early September, using a simplified undocking system to get the vehicle away from ISS quickly. The next Dragon mission will launch no earlier than September 24th carrying two astronauts and two empty flight suits that Wilmore and Williams use during their return.

According to NASA and Boeing officials, ground static fire engine tests have now identified the likely cause of the thruster failures on the Starliner capsule during its docking to ISS in early June, and puts them in a position next week to determine a return date for the capsule and its two astronauts.

It appears the problem is related to teflon seals in the thrusters, detected while engineers did a series of tests on the ground with another Starliner capsule. Based on this information, Boeing thinks it can fix the problem on future capsules, while also insuring there will be no problems returning the astronauts from ISS.

The thrusters in question are all attitude thrusters, where there is a lot of redundancy and the issue has been seen to be well controlled from the start. The larger thrusters used for the undocking and de-orbit burn have been tested as well, and have not shown any similar issues at all.

The ground tests have also identified the cause of the helium leaks within the capsule engine system. Boeing will use this data to fix later capsules as well. These leaks are not a concern for the return to Earth.

The plan now is to do in the next few days one more set of static fire tests with the capsule docked on ISS, doing short bursts with all the attitude thrusters to further confirm what has been learned on the ground. If that goes as expected, a final meeting next week will determine the return date for the capsule and crew.

Starliner docked during the unmanned demo
flight in May 2022

According the NASA and Boeing officials yesterday, they are in the process of doing ground thruster tests to emulate the problems that occurred on the thrusters during docking procedures to ISS in early June, and will not decide on a return date for Starliner until after those tests are completed and analyzed, expected sometime in the next two weeks.

It appears some of the ground tests were delayed slightly due to the arrival of Hurricane Beryl in Texas.

It is very important to note that the astronauts are not “stranded” on the station, as a lot of news organizations are still claiming. The thrusters on Starliner that failed are part of the service module, which will not return to Earth when the astronauts come home on the the capsule. They therefore want to do as much research as possible beforehand in order to determine the cause of the failures in order to prevent them on future capsule flights. For example, the ground tests are first attempting to duplicate precisely what happened during docking, and will then do tests attempting to duplicate what will happen during de-orbit.

In the meantime, they appear to have no doubt that they can use Starliner for return, no matter what. At the moment only one thruster appears out-of-commission, and none of the thrusters that failed during docking are used for the de-orbit burn. They are only used for orientation, and the capsule has ample redundancy for this function sufficient for de-orbit.

In addition, it is a good thing for them to extend Starliner’s total flight time. I suspect even if everything had worked as planned they would have extended this mission as they have. This allows them to prove out the in-space operation of the capsule and service module. So far it appears that operation has been excellent, which is one reason they are willing to delay the return to do the ground tests.

Overall, my impression is that the situation is entirely under control, and in fact NASA is reasonably satisfied with the capsule’s operation in general. It appears that the agency will likely have no problem in flying future manned missions with Starliner, though it will want the thruster issue solved beforehand.

As for Boeing, these problems have stained its reputation further, and have likely made it much more difficult to sell future capsule flights to other customers. I would say however that after listening to the last few press briefings it seems to me that Boeing’s manned space division is now doing the proper due diligence it should have done before. For example, the thruster problems appear to be related to overheating during use, which is a very fixable issue.

These facts actually makes me more confident in the capsule, and future potential customers should do the same review themselves.