I can understand the sense of "we just spent 8.7 billion dollars on this thing; we'd better not screw it up", but I wonder what the replacement cost would actually be if they had to launch another? Assuming they spent most of the money on R&D, it might actually be relatively cheap. Maybe we could even launch a couple smaller versions just to have backups and do the science tasks that don't require a full 21' mirror.
There's an interesting contrast between NASA's and Elon Musk's idea of what space exploration should be like; the former spends most of its efforts on one-off projects, whereas the latter is focused on making things cheap and repeatable and achieving reliability by iterating on a design rather than getting it perfect the first go-around.
Both approaches are needed, and certainly NASA paves the way for others to come along and do the same thing cheaper once it's been proven.
We currently have the 80 cm Spitzer telescope in space that covers the same wavelength range, and the 3.5 m Herschel telescope also recently finished its mission at slightly longer wavelengths. So really to make breakthroughs in science to justify the cost of a space mission, we need the full 6.5 m telescope.
There is also SOFIA [1] (2.5m telescope on an airplane), which can do certain far-IR things (mid-IR as well iirc).
For the VLT (8m ground-based telescopes) there is also VISIR [2] which is an mid-IR imager/spectrometer (and uses the same detector chip as one of the JWST instruments iirc).
Oh yeah, those do cover the same wavelength range. The atmosphere of the Earth absorbs a lot of the light and has a strong thermal background though. The sensitivity of JWST is orders of magnitude better than ground/airborne observatories [1], so things that JWST want to do will be basically impossible from the ground.
While I will gladly rant about my issues with how NASA handles things: NASA and Musk are trying to solve different problems
Musk's goal is affordable space travel
NASA's goal was space travel (and exploration) period.
That means everything is a prototype. As for why we don't re-use them that much: By the time a project is over, so much has been learned that it and said knowledge needs to be applied to the next round.
In the case of space telescopes and the like: Repairs are made (if memory serves, Hubble was the one that famously launched with defects and needed to be fixed in orbit). As for launching more smaller ones: There just isn't a huge need for it. Getting time on a telescope is something even a grad student can do and the timescales are such that there is very rarely a "we need this NOW! Screw everyone else and block off a few weeks for us" situation. And if there is? Odds are a LOT of people want that data anyway.
One way to think of it is like a gaming PC. Some people buy mid-end and make incremental updates over the lifecycle of the machine. Others go all out and just build a monstrocity with an i7 every 4-6 years.
You may not be able to do the kinds of science that will test the hypotheses you want to evaluate. We could build a lot of Zero Gradient Synchrotrons for what the Large Hadron Collider cost, but the ZGS isn't anywhere close to being powerful enough to measure the properties of the Higgs boson. Another example: For less than USD 500 an individual may outfit themselves with an optical telescope more accurate, more precise, and more powerful than anything available to Galileo or Kepler or Newton, but such a "cheap and repeatable" device will never be capable of sensing the gravitational waves detected by the LIGO and Virgo laser interferometers. Also, that $500 Celestron is only possible because of all of the one-off telescopes that came before it. You have to start somewhere, and NASA is that somewhere for space science.
Just because I can get 1,000 10 dollar optical microscopes for the cost of a single 10k electronic microscope does not mean that an equal about of science can be done.
This paper, from 2014, says that the Hubble space telescope is oversubscribed by 4:1 to 5:1. [1] That's a higher acceptance rate than most government funding grants these days (unfortunately). Perhaps it suggests that there is still a lot of unmet demand for good science to be done with it.
> what the replacement cost would actually be if they had to launch another?
I wonder if they considered just launching a repair-buddy satellite ? So basically a robotic toolbox with a ton of spare parts that could cover 95% of the possible failures of the thing. Then if they get it up there and find out the panels wont open, or the mirror gets stuck, they could pop it open and get it ready before they send it to the lagrange point.
You might as well just send up a second one, rather than send something that is 95% of the first one plus a very complicated system of robot arms to do arbitrary repairs and replacements.
It is interesting, but also perfectly appropriate within mainstream economic theory that a private corporation be responsible for the latter goals, and the former are with appropriate government subsidies.
I can assure you that there is very little design commonality between JWST and surveillance satellites. JWST is a very unique mission that is completely different from that of spysats.
This is probably unlikely as JWST is designed to fly in L2 and not in a geosynchronous orbit. Additionally, at the wavelengths it is operating at (mid-infrared), if it pointed towards Earth, it'd just see the heat of the Earth's atmosphere. Probably not very great for spying.
There's an interesting contrast between NASA's and Elon Musk's idea of what space exploration should be like; the former spends most of its efforts on one-off projects, whereas the latter is focused on making things cheap and repeatable and achieving reliability by iterating on a design rather than getting it perfect the first go-around.
Both approaches are needed, and certainly NASA paves the way for others to come along and do the same thing cheaper once it's been proven.