Re:James Webb is fully deployed
by WalterBright on Saturday January 08, 2022 @08:37PM
(#29858887)
Another poster here remarked that spares would be made. That would indicate the cost of doing so isn't that remarkable.
Lots of engineering models. Some spare parts for parts of assemblies.
Not a lot of complete, flight-capable assemblies.
I'm actually teaching a bunch of high school students to make a cubesat right now, and we are going through costing of:
* Prototypes -> protoflight -> flight, no engineering model
* "Flatsat" electronic engineering model, prototypes -> protoflight -> flight
* Prototypes -> qualification article -> flight article, + "flatsat"
* Prototypes -> qualification article -> flight article + ground engineering model
There's a whole lot of derisk that happens as you go down that list, but the cost and labor increase (the latter is "free" for us but also limited) is substantial.
I think 30% is probably a reasonable guess, based on past programs where people have flown 2. You get to reuse design and some fixturing. You get to share some operational costs. But you're not at unit counts where you benefit from mass production techniques and a whole lot of verification and qualification work are still effectively one-offs for each one.
(You save a whole bunch of costs related to making a repeatable program that can turn out hundreds of an item, but more has to be validated/verified for each unit).
The thing is-- what's the marginal value of the additional data (and of the higher priority data arriving earlier)? Would you rather have 2 James Webbs for $13B, or 1 James Webb & some other $3B mission?
(Or, at the outset/original decision making: do you aim for 2 somewhat simpler telescopes or 1 really awesome telescope with the block of money you're given?)