Also, if I have understood things correctly, the lunar lander used a timer based approach to keep the rotation of the vehicle aligned with the surface of the moon as it orbited.
Since the orbital dynamics are very well understood and there really isn't anything that can affect the motion of the spacecraft other than engine burns, there doesn't seem to be any good reason to make it more complicated.
This is wrong.
1) Atmospheric drag (unless you're in really high orbits)
2) Wind
3) Uneven gravitational field. Our planet is not a perfect sphere. The moon is even less so.
4) Solar pressure (though very minor and kinda evens out in orbit).
Space is empty enough and engines imprecise enough that for orbital stuff you have enough margins to correctly predict and plan a trajectory ahead of time, and just do correction burns later if necessary.
On the Moon the gravitational field is indeed uneven enough to matter, but exactly one orbiter really cares about it (LRO iirc has a specific orbit where the unevenness mostly cancels out), most simply rely on occasional station keeping burns.
But regardless, this was a Boeing spacecraft; it wasn't built by NASA (NASA generally does systems engineering; contractors build things like this).
But many things can go slightly wrong when firing all engines fighting your way up the atmosphere.
It would seem we have an existence proof now saying that the above statement is incorrect.
The wording “it would seem” should have tipped you off that no assumptions are being made, but I guess it didn’t work.
And even if we were to make a comparison as you suggest and derive some ratio, that’s not super useful without comparing it to the ratio for some alternative approach that does not use timers.
This is like saying that because the airplane crashed because the wing was incorrectly designed and popped off, everyone should fly biplanes...
We do that. Not with the wings, but with the engines. When jetliner engines were less reliable, we required 3 or more engines on flights that included long sections without passing near an airport (mostly transoceanic flights). Now that some engines are more reliable, we have ETOPS certifications for jetliners using two high-reliablility engines. And yes, there still are two, because no matter how reliable the engines may be, one _may_ fail.
What is backing up that CST-100 timer?
Think about this - if you're one of those software engineers and you read some random person on forums criticizing your work without context or thorough understanding, how would you feel?
I love HN for insight and intellectual debate, this kind of analysis does not add any insight - it is flat out dismissing and condescending.
Edit: Also, this behavior against Boeing is unwarranted because it has bias of 737 MAX issues. Completely different team, completely different problem.
This leads to a phenomenon where software engineers tend to come up with "one weird trick to solve the space shuttle, NASA hates him". And it's always specifically software engineers.
Generally, most people are just as competent at their job as you are at yours. If the obvious solution is not being used, there is usually a very good reason why. A lot of fields have problems that are hard for reasons of physics or other things that are not trivially gone around, and the solution is not one software engineer swooping in with a great idea that totally revolutionizes avionics.
(sometimes of course it is social factors, same as software engineering. The best way is too expensive, or management is making bad decisions, etc)
I wouldn't doubt most programmers could do an failure mode effects analysis on the software and figure out they need to mitigate an event where the timer fails to sync. But how many would also capture how to mitigate that sync failure at the precise time the system lost satellite comm? Probably a heck of a lot less.
Now multiply that by the total number of software failure modes (including those latent ones we just get lucky with) and see how many get captured. There's a reason why software in these types of systems is incredibly hard to test.
Wrong. Do you somehow thing there's a different management team running these parts of the company? There's only one CEO at Boeing, it's only one company. And culture starts at the top.
Questioning Boeing's competence here is entirely warranted when the company has already PROVEN that it is happy to put profits ahead of safety.
It...seems sort of similar to me, based on the article I read. It's not similar at all in the consequences, because of the context of the flight. But in the way things went wrong.
A question that I have unanswered is, Boeing was reported as saying that if there were astronauts they would be "safe"...but would it be possible to retrieve them?
SHIT happens in space flight all the time. The rate at which shit happens in space is on a few orders of magnitude different than shit that happens in commercial aerospace. Ask how many times SpaceX failed to do what they do today and it will fail more times in future, no doubt.
I also understand the company culture point - yea, company culture probably isnt the best at Boeing but they've done many many things right in past decades. They're a huge company with a lot of talented engineers (and a lot of bozos). Their CEO is a complete asshat and I am sure people inside Boeing talk about it.
I just think that there is unnecessary scrunity without data to say definitively what happened.
That's internet in a nutshell, and HN is not that different despite pretensions to the contrary. What partly redeems it is the better than even chance that in posts with technical subjects, someone informed and/or competent will appear and write something worthy. You learn to filter out the rest.
Who gives a shit how he feels? He works at a company that builds death traps, and someone at that company has built one himself. People like this should feel overpowering shame and contemplate the poor life choices that brought them to this terrible place.
Boeing is a great argument for the corporate death penalty. Its stock price should go to zero, and its assets divided between its creditors and the military pieces nationalized.
I imagine the reason timers are used is this right here. We don't have complete coverage of the earth for satellite control, so there needs to be a timer running for when it can't phone home to stay synchronized.
Interesting, this might explain the failure to land the rover (vikram) on the dark side of the moon by India's recent moon mission.
For example, what if the altitude assumed by the timer is off by a few kilometers, and it starts operating in a manner which is for landing within few meters.
Astonishing to me they make it sound like it runs like an independent stopwatch and not kept in sync with the actual IRL mission parameters in a more direct/continuous way. They're talking about the automation handover between the launch vehicle to the spacecraft, and on Starliner "clearly the time got messed up" ... "the spacecraft was not on the timer we expected it to be on"