Updates Boeing's CST-100 Starliner

[Thunder Chicken]

So Starliner read the wrong time from Atlas V.

“Our spacecraft needs to reach down into the Atlas 5 and figure out what time it is. We reached in and grabbed the wrong coefficient.”

:facepalm:

Can someone explain what happened, or link to something that explains it?

 

[Urwumpe]

Can someone explain what happened, or link to something that explains it?

Not sure there what it means. If it is the capability to read the MET timer of the centaur stage, it is non-standard for a Atlas V.

 

[barrygolden]

Remember had John Glenn been onboard he could have fixed that issue in real time just as Alan Bean saved Apollo 12 with the SCE to AUX switch throw. I left work late last night to drive home and before I turned down the shop lights I was looking and Crewed Dragon 4 and 5 and hoping we haven't missed something to cause an issue with these two craft. I'm proud of the Boeing team that put CST up and brought it home. Super Job !!!

 

[GLS]

 

[4throck]

I'm quite confident about both capsules (Boeing & SpaceX) right now.
Yes, that software needs better debugging (even Mercury was able to fly autonomously ) but overall it worked. They were able to control it and the capsule landed on target.

For me it looks safe and good to go (the same for Crew Dragon).
Time to start flying

 

[MaverickSawyer]

I wouldn't be so quick to get onboard...

https://arstechnica.com/science/202...y-looking-at-starliners-thruster-performance/

During the post-flight news conference Jim Chilton, Boeing's senior vice president of the Space and Launch division, said the service module thrusters were stressed due to their unconventional use in raising Starliner's orbit instead of performing one big burn. As a result, the company had to shut down one manifold, which effectively branches into several lines carrying propellant to four thrusters. "We even shut down one manifold as we saw pressure go low 'cause it had been used a lot," he said.

The NASA source said eight or more thrusters on the service module failed at one point and that one thruster never fired at all.

 

[Urwumpe]

Yeah, a bit of work left. The question though is, why?

 

[4throck]

One thing is certain, the capsule did reenter on target and on time.
You need RCS attitude control to do that. So the system was working, at least for/during the reentry burn.
Let's wait for the final report.

 

[GLS]

So the system was working, at least for/during the reentry burn.

Correction: enough of the system was working. They might have had no redundancy, and thus be one failure away from a ballistic entry* or worse. :shrug:

*) can these new capsules do that?

 

[Urwumpe]

*) can these new capsules do that?

AFAIR yes.

 

[fred18]

I wouldn't be so quick to get onboard...

https://arstechnica.com/science/202...y-looking-at-starliners-thruster-performance/

I have to say that it is quite surprising to me. I know I know, flying in space is very difficult, etc etc, but still this capsule was not developed in six month in a rush but in many years, and with modern tech I was expecting some minor glitches with some fixes here and there as usual with a complex system, but that's it. Not such a large scale number of issues...

 

[GLS]

I have to say that it is quite surprising to me. I know I know, flying in space is very difficult, etc etc, but still this capsule was not developed in six month in a rush but in many years, and with modern tech I was expecting some minor glitches with some fixes here and there as usual with a complex system, but that's it. Not such a large scale number of issues...

The thruster firing limitations are almost certainly not "hard-coded" in the software. Instead they design the control system such that the thruster usage is inside the safe zone of thruster operation.
E.g., say the thrusters can only safely fire continuously for 5s (and then need to cool off), so they do the math and that would produce a 10º/s rotation, so they make the flight control system with a 8º/s max rate, thus even firing to get to max rate they will never exceed the 5s firing limit.
Obviously they didn't consider all the scenarios in designing the flight control system and ended up exceeding the thruster limits, or the thrusters aren't as good as they thought.. :shrug:
And there is also the clock issue.

 

[4throck]

Apollo also had some issues with RCS overheating. If I'm not mistaken, one Skylab docking was done with one jet non-operational ?

Not trying to be optimistic, but the problems might be related to pushing the system beyond the design parameters. On this case to save the mission...
That's why I want to see the final report.

But I do agree that I expected it to go more smoothly. Capsules are not a novelty.

 

[DaveS]

Apollo also had some issues with RCS overheating. If I'm not mistaken, one Skylab docking was done with one jet non-operational ?

Not to mention how many times the shuttle had issues with its RCS jets. They failed plenty of times, some times just not off but also leak. STS-63 suffered two separate RCS jet leaks (R1U failed leak shortly after launch and F1F also failed leak on FD2) that nearly derailed the plans to have Discovery rendezvous and perform a fly-around of Mir. Thankfully a procedure to cycle the F1 manifold valves stopped the leak of F1F and and R2U and R4U jets were healthy and available to take over in place of the failed R1U jet.


So jet losses aren't as bad as they seem to be provided that there's multiple jets that fires in the same direction. STS-121 performed ISS rendezvous and prox ops with the entire vernier jet system out of action due to a failed heater on the L5L jet (flight rules stated that the entire vernier jet system would considered failed in the event of a heater loss for just one vernier jet as there's only six vernier jets and none is redundant unlike the primary jets).

 

[Urwumpe]

Not to mention how many times the shuttle had issues with its RCS jets.

Well, essentially, CST-100 and STS orbiter have the same manufacturer. :tiphat:

 

[Donamy]

...also the lowest bidder.

 

[MaverickSawyer]

I think Donamy just hit the nail on the head. It's a Boeing program, and right now, they've dug themselves a mighty deep hole with their pursuit of profits. It's going to take them some serious effort to get out of their current situation by correcting the systemic cultural issues now facing them, and it seems like Starliner got caught in the mess.

 

[GLS]

Starliner faced “catastrophic” failure before software bug found
"If it had gone uncorrected it would have led to erroneous thruster firing."
https://arstechnica.com/science/2020/02/starliner-faced-catastrophic-failure-before-software-bug-found/

 

[Notebook]

Thanks for that GLS, last sentence is a doosy!

 

[4throck]

"While this anomaly was corrected in flight, if it had gone uncorrected it would have led to erroneous thruster firing and uncontrolled motion during SM separation for deorbit, with the potential for catastrophic spacecraft failure"
"Had the error not been caught, the source said, proper thrusters would not open during the reentry process, and the vehicle would have been lost."
"Given the potential for systemic issues at Boeing, I would also note that NASA has decided to proceed with an organizational safety assessment with Boeing as they previously conducted with SpaceX"


This is very bad...