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Engineers at heart wouldn't let a single point of failure in in the design of it to let a pin drop unexpectedly. Is the vehicle insured for a do-over should it

Engineers at heart wouldn't let a single point of failure in in the design of it to let a pin drop unexpectedly. Is the vehicle insured for a do-over should it fail to launch unspectacularly and land in the water?

edgyquant 5y ago
With how long it’s been planned a do-over would involve a new telescope I’d think.
scrooched_moose 5y ago
I'd imagine there were redundant systems that caught it, but it still caused a significant shift in load distribution and possibly the satellite to drop some distance which would impart an acceleration load.
- dylan604 5y ago
  I wonder how much shock the system is going to take to use a persuasion tool (aka mallet) to release it from this "redundant" system you imagine. My imagination is much less prolific and see it wedged in at an angle in a way not imagined by the deigners.
Enginerrrd 5y ago
In many systems, yes, that's to be avoided. However, the space industry as a whole is so tightly constrained that it's a necessary evil to eliminate redundancy and even reduce safety factors below ideal.
shantara 5y ago
After watching an official JWST video https://www.youtube.com/watch?v=uUAvXYW5bmI https://www.youtube.com/watch?v=uUAvXYW5bmI, they seem almost proud of having several hundred of single points of failure and an immensely complex deployment process that takes several weeks and must work perfectly. I don't know what engineer could be proud of coming up with a design like that.
- NikolaeVarius 5y ago
  Its a machine that is extremely mass limited, has many different groups of people influencing different systems, and is extremely complex. If the HARD requirement is "you have this much mass and volume to make a thing to a particular confidence score" you make the damn thing and hope you are on the correct side of the dice. No single engineer gives a shit about the entire system because no single person is equipped with the human ability of comprehending each individual part that has whatever confidence rating that is required.
  - spaetzleesser 5y ago
    Makes me wonder if the future is in launching things in parts and assembling things in space. This probably has its own set of problems though.
    - sgtnoodle 5y ago
      That would be pretty cool if it could be done inside a pressurized workspace. Humans could do the work of massive cranes.
- Out_of_Characte 5y ago
  Single points of failure are inevitable. engineers could always make a copy of the entire design but that would double the costs and you would still be left with unknown points of failure that the telescope double would have. The solar shield is like rolling out five layers of tightly packed tinfoil from several points without tearing. Claiming that you would do away with single points of failure if you were the one designing it is too easy to say on HN
  - shantara 5y ago
    I'm not arguing you could completely go away with single points of failure when designing a spacecraft while being limited by the payload mass and volume. But the whole JWST unfolding sequence looks like a way too risky gamble to me. Maybe, it was worthwhile to sacrifice some of the scientific payload mass to add more redundancies into the solar shield design and increase the chances the telescope would be able to reach the beginning of its observation process. There's also the whole "what if we could avoid mass and volume constraints" tangent, that was discussed in the yesterday's Starship article, but it's more of a theoretical consideration for now.
willis936 5y ago
10 Bn USD projects are not insured.
- bumby 5y ago
  Almost no government space project is insured. The govt is self-insured, generally. Which incidentally, means private space companies are effectively out-sourcing much of their govt contract risk to the taxpayer

edgyquant 5y ago

With how long it’s been planned a do-over would involve a new telescope I’d think.

scrooched_moose 5y ago

I'd imagine there were redundant systems that caught it, but it still caused a significant shift in load distribution and possibly the satellite to drop some distance which would impart an acceleration load.

dylan604 5y ago
I wonder how much shock the system is going to take to use a persuasion tool (aka mallet) to release it from this "redundant" system you imagine. My imagination is much less prolific and see it wedged in at an angle in a way not imagined by the deigners.

Enginerrrd 5y ago

In many systems, yes, that's to be avoided. However, the space industry as a whole is so tightly constrained that it's a necessary evil to eliminate redundancy and even reduce safety factors below ideal.

shantara 5y ago

After watching an official JWST video https://www.youtube.com/watch?v=uUAvXYW5bmI https://www.youtube.com/watch?v=uUAvXYW5bmI, they seem almost proud of having several hundred of single points of failure and an immensely complex deployment process that takes several weeks and must work perfectly. I don't know what engineer could be proud of coming up with a design like that.

NikolaeVarius 5y ago
Its a machine that is extremely mass limited, has many different groups of people influencing different systems, and is extremely complex. If the HARD requirement is "you have this much mass and volume to make a thing to a particular confidence score" you make the damn thing and hope you are on the correct side of the dice. No single engineer gives a shit about the entire system because no single person is equipped with the human ability of comprehending each individual part that has whatever confidence rating that is required.
- spaetzleesser 5y ago
  Makes me wonder if the future is in launching things in parts and assembling things in space. This probably has its own set of problems though.
  - sgtnoodle 5y ago
    That would be pretty cool if it could be done inside a pressurized workspace. Humans could do the work of massive cranes.
Out_of_Characte 5y ago
Single points of failure are inevitable. engineers could always make a copy of the entire design but that would double the costs and you would still be left with unknown points of failure that the telescope double would have. The solar shield is like rolling out five layers of tightly packed tinfoil from several points without tearing. Claiming that you would do away with single points of failure if you were the one designing it is too easy to say on HN
- shantara 5y ago
  I'm not arguing you could completely go away with single points of failure when designing a spacecraft while being limited by the payload mass and volume. But the whole JWST unfolding sequence looks like a way too risky gamble to me. Maybe, it was worthwhile to sacrifice some of the scientific payload mass to add more redundancies into the solar shield design and increase the chances the telescope would be able to reach the beginning of its observation process. There's also the whole "what if we could avoid mass and volume constraints" tangent, that was discussed in the yesterday's Starship article, but it's more of a theoretical consideration for now.

willis936 5y ago

10 Bn USD projects are not insured.

bumby 5y ago
Almost no government space project is insured. The govt is self-insured, generally. Which incidentally, means private space companies are effectively out-sourcing much of their govt contract risk to the taxpayer