Re:James Webb is fully deployed
by rcxdude on Sunday January 09, 2022 @05:18AM
(#29862029)
> Yes, it'll be heavier, and that will cost more.
It won't just cost more, it'll be impossible. Aircraft care a lot about weight, spacecraft are obsessed with it, because it's often an absolute limit based on what launch technology you have available and where you're trying to get. JWST doesn't have any spare weight to try to build more redundancy.
> But suppose for $1B one could build a less reliable JWST
Well, the calculus of many single failure points makes this questionable. Even if you're 99% confident in each point of failure, with 390 failure points you have a 2% chance of success. You need extremely reliable components. Also, it's not clear that the majority of the budget is being spent on increasing that reliability: certainly a lot goes into testing, but all of that testing is generally a lot cheaper than a launch and rebuild.
It won't just cost more, it'll be impossible. Aircraft care a lot about weight, spacecraft are obsessed with it, because it's often an absolute limit based on what launch technology you have available and where you're trying to get. JWST doesn't have any spare weight to try to build more redundancy.
> But suppose for $1B one could build a less reliable JWST
Well, the calculus of many single failure points makes this questionable. Even if you're 99% confident in each point of failure, with 390 failure points you have a 2% chance of success. You need extremely reliable components. Also, it's not clear that the majority of the budget is being spent on increasing that reliability: certainly a lot goes into testing, but all of that testing is generally a lot cheaper than a launch and rebuild.