Not sure which configuration this launch entails but the telescope itself weighs 6,500 kg, so that sounds like a lot of energy to account for.
Ariane 5 user's manual, PDF: https://www.arianespace.com/wp-content/uploads/2015/09/Arian...
It's always agrressive against the users. The users are the poor saps that have to accept whatever the devs have droped on them. The users have no say other than suggest it doesn't work, doesn't promote efficient workflows, whatever. It's then up to the devs to fix, but they feel like they've delivered according to specs so tough. The User will Accept Whatever from the all powerful dev team. How about User Acceptability Testing. At least it then makes it sound like the devs are going to give a damn about the users feedback.
I think it just goes to show that nobody likes creating documentation.
But it's odd to see that on word documents themselves.
Either way, it's chuckles all the way down.
https://www.ulalaunch.com/docs/default-source/rockets/atlasv...
Though do note:
> This user’s guide is intended for pre-contract mission planning and for understanding SpaceX’s standard services. The user’s guide is not intended for detailed design use. Data for detailed design purposes will be exchanged directly between a SpaceX customer and a SpaceX mission manager.
dozens if not hundreds of HNers begin poring thru the manual
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.
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
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.
So, what I learned is that single points of failure on initial deployment -- which by definition only has to run once -- is a drastically different cost vs risk calculation than something that happens during normal operations.
You are right that a magical rocket could solve many of NASAs problems (just launch ten Webbs and use the ones that don't work as sunshades for the rest!) but I think NASA is being pretty practical in not waiting for one to be invented.
What was the original budget for JWST? Where's it at now? From your assessment and the numbers, it sounds like there's not just double but triple redundancy now.
Still though, if everything works and we learn more about the universe, I think it'll have been worth it.
(Ok, "weeks" isn't quite applicable in that case... Unless you're counting the time for updates to propagate through all upstream dependencies.)