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The cost doesn't come from a lack of production efficiency. A significant fraction of the cost is for testing/validation of the spacecraft, which must be done f

The cost doesn't come from a lack of production efficiency. A significant fraction of the cost is for testing/validation of the spacecraft, which must be done for every unit you produce. Simulating operating conditions on Earth is extremely expensive and time consuming.

aero-glide2 5y ago
When you build 20 scopes you can use the fail fast approach to better iterate on the next versions. It's okay if the first few fail.
- petschge 5y ago
  Except after the second failure you have a REALLY hard time to get funding out of politicians...
  - loonster 5y ago
    Its about setting proper expectations. Its not a failure if its expected. Get the politicians to commit to all 20 launches in advanced.
    - rizky05 5y ago
      How do you know it only needs 20 launches ?
holler 5y ago
It's the same reason SpaceX is eating Boeing's lunch with their space program. One uses an iterative build process, and the other uses the more historical waterfall method. That's not to say waterfall didn't or doesn't have merit here, just that it seems like technology has advanced to a place where hopefully in the future we can build these things much faster and cheaper, such that the stakes aren't so high for a single unit.
- stopping 5y ago
  I don't disagree with your point re: Boeing v SpaceX, but precision scientific instrumentation is a very, very different domain where "move fast and break things" cannot be naively applied. The sensitivity to failure is so ridiculously high that you need 6 to 7 sigmas of reliability for each of ten thousand critical components in order to even have just a 90% chance of mission success. Something as simple as an instrument bring slightly out of tolerance, faulty rad-hardening on a CPU, the sun shield having a minor tear, are all enough to completely jeopardize the entire mission. As a fully integrated system, JWST is at least an order of magnitude more complex than Starship, whose main design goals (launch, orbit, land, don't explode) tend to favor a more iterative approach.
  - gfodor 5y ago
    Pretty sure this argument could have been levied against rocketry. For scientific telescopes most likely a frame shift would be needed to break out of this mindset that would be analogous but distinct from the one applied to rocketry.
    - stopping 5y ago
      There are two key differences between rockets and space telescopes (any space-faring probe, really) which prohibits "iterate to failure" as a development technique: 1. Forensics difficulty. You need extensive data to debug issues for complex systems. You can collect so much more data from terrestrial testing, which allows you to do the extensive forensic analysis required to achieve the required component reliability. Once you put a telescope in space, you can't inspect it anymore. A lot of the sensitive components which might fail on JWST have to be inspected to microscopic precision in order to perform adequate failure analysis. 2. Design requirements are far, far more precise. Many failures in deep space are effectively impossible to correct in later iterations due to point 1. Telemetry and sensor data is enough to debug rockets, but for JWST you would need to ship so much extra data/sensor infrastructure alongside the telescope that the whole project becomes recursively intractable. The system complexity is so high that you absolutely must have the ability to make arbitrary system corrections because the chance of "building everything correctly the first time" is effectively zero, even with perfect hindsight! Essentially, any time you build the thing from scratch, you will always find mission-ending statistical deviations. The objective of on-ground testing is to identify and correct those specific deviations, until the whole system is within design tolerances. If you were to totally rebuild it, the next iteration will have a totally different set of statistical deviations which will need to be corrected. This process of development involves "hardening" the entire system through extensive testing, because it impossible to build a fully-hardened system to start with, even after "learning" from previous attempts.
gpm 5y ago
If you can produce them cheaply but not test them cheaply, the solution is really simple, just don't test them. Send them to space, see what happens. It's not like space telescopes need any of the valuable orbit space, and even if they did it's easy to put thrusters on board that can de-orbit them or move them to a graveyard orbit (depending on their operational orbit) in the case of failure.
- stopping 5y ago
  I addressed this in another comment: https://news.ycombinator.com/item?id=28452001 https://news.ycombinator.com/item?id=28452001 To summarize, you have to have the ability to correct statistical aberrations after manufacture via extensive validation and testing, as opposed to design aberrations which can largely be eliminated through destructive iteration. Without the former process, you'll launch a million telescopes and not a single one will work.

aero-glide2 5y ago

When you build 20 scopes you can use the fail fast approach to better iterate on the next versions. It's okay if the first few fail.

petschge 5y ago
Except after the second failure you have a REALLY hard time to get funding out of politicians...
- loonster 5y ago
  Its about setting proper expectations. Its not a failure if its expected. Get the politicians to commit to all 20 launches in advanced.
  - rizky05 5y ago
    How do you know it only needs 20 launches ?

holler 5y ago

It's the same reason SpaceX is eating Boeing's lunch with their space program. One uses an iterative build process, and the other uses the more historical waterfall method. That's not to say waterfall didn't or doesn't have merit here, just that it seems like technology has advanced to a place where hopefully in the future we can build these things much faster and cheaper, such that the stakes aren't so high for a single unit.

stopping 5y ago
I don't disagree with your point re: Boeing v SpaceX, but precision scientific instrumentation is a very, very different domain where "move fast and break things" cannot be naively applied. The sensitivity to failure is so ridiculously high that you need 6 to 7 sigmas of reliability for each of ten thousand critical components in order to even have just a 90% chance of mission success. Something as simple as an instrument bring slightly out of tolerance, faulty rad-hardening on a CPU, the sun shield having a minor tear, are all enough to completely jeopardize the entire mission. As a fully integrated system, JWST is at least an order of magnitude more complex than Starship, whose main design goals (launch, orbit, land, don't explode) tend to favor a more iterative approach.
- gfodor 5y ago
  Pretty sure this argument could have been levied against rocketry. For scientific telescopes most likely a frame shift would be needed to break out of this mindset that would be analogous but distinct from the one applied to rocketry.
  - stopping 5y ago
    There are two key differences between rockets and space telescopes (any space-faring probe, really) which prohibits "iterate to failure" as a development technique: 1. Forensics difficulty. You need extensive data to debug issues for complex systems. You can collect so much more data from terrestrial testing, which allows you to do the extensive forensic analysis required to achieve the required component reliability. Once you put a telescope in space, you can't inspect it anymore. A lot of the sensitive components which might fail on JWST have to be inspected to microscopic precision in order to perform adequate failure analysis. 2. Design requirements are far, far more precise. Many failures in deep space are effectively impossible to correct in later iterations due to point 1. Telemetry and sensor data is enough to debug rockets, but for JWST you would need to ship so much extra data/sensor infrastructure alongside the telescope that the whole project becomes recursively intractable. The system complexity is so high that you absolutely must have the ability to make arbitrary system corrections because the chance of "building everything correctly the first time" is effectively zero, even with perfect hindsight! Essentially, any time you build the thing from scratch, you will always find mission-ending statistical deviations. The objective of on-ground testing is to identify and correct those specific deviations, until the whole system is within design tolerances. If you were to totally rebuild it, the next iteration will have a totally different set of statistical deviations which will need to be corrected. This process of development involves "hardening" the entire system through extensive testing, because it impossible to build a fully-hardened system to start with, even after "learning" from previous attempts.

gpm 5y ago

If you can produce them cheaply but not test them cheaply, the solution is really simple, just don't test them. Send them to space, see what happens. It's not like space telescopes need any of the valuable orbit space, and even if they did it's easy to put thrusters on board that can de-orbit them or move them to a graveyard orbit (depending on their operational orbit) in the case of failure.

stopping 5y ago
I addressed this in another comment: https://news.ycombinator.com/item?id=28452001 https://news.ycombinator.com/item?id=28452001 To summarize, you have to have the ability to correct statistical aberrations after manufacture via extensive validation and testing, as opposed to design aberrations which can largely be eliminated through destructive iteration. Without the former process, you'll launch a million telescopes and not a single one will work.