I imagine the only realistic repair mission would be with a Starship crew, seeing as Orion and all the other Commercial Crew vehicles would probably require some additional components to make it out that far and to sustain their crews. Starship seems big enough and far enough along in development to be viable.
Edit: The JWST has a docking ring to let Orion service it. But I don't know if the SLS in it's available configurations can get it up there. It seems like a contingency but I don't see any solid information about an Orion service mission.
I think you already said it. The long life (high reliability) requirement, and I'll add the complexity of having it unfold. Both of those become non-issues if you build the telescope right into a space-X starship. There may be other issues with that, but the mirror wouldn't need to fold ;-)
Additionally, the engineering requirements for long-term life support are significantly more involved than the Dragon capsule.
There's also the testing and certification process for crewed-missions; in non-Elon time, this is likely several years, conservatively speaking [1]. (I'd love to be proven wrong, however!).
[0] https://www.space.com/spacex-starship-super-heavy-booster-ro...
[1] https://arstechnica.com/science/2021/04/five-reasons-why-nas...
My guess was that the clamp was mainly for possible future replenishment of consumables, though presumably some sort of robotic-arm-equipped repair mission could attach as well. A crewed mission seems possible, too, assuming one of the planned Lunar craft could be modified to go to the Lagrange point.
https://www.space.com/3833-nasa-adds-docking-capability-spac...
https://en.wikipedia.org/wiki/Spacecraft_Bus_(JWST)#Docking_...
There is hope for the robotic refueling type mission though, or at least the kind where a new utility bot attaches to an old satellite and takes over propulsion to extend its life.
True, but a docking adapter with an airlock that works with starliner and dragon is technically feasible. That said, it would still likely require recertification, as its inclusion would effect abort modes.
Also, congress would be extremely critical of NASA if JWST fails. They would not be excited to shell out another $0.5 billion for a chance to fix it.
JWST in comparison is a far trickier and complicated beast to tinker with. This is the biggest reason why they are so paranoid about any fault before orbital launch. It would be all but impossible to service it - on both a technical and political level.
If that was the cost for that mission, it would be worth it considering JWST cost about 20x that amount.
https://m.fanfiction.net/s/11685932/1/Instruments-of-Destruc...
Space Shuttle could not have reached it.
Does use of the thrusters impact the sensors that the telescope uses?
> One kind is called "Secondary Combustion Augmented Thrusters" (SCAT), and they are used for orbit correction (like applied changes in velocity for each maneuver the spacecraft makes and also for orbit station-keeping). The SCATs are bi-propellant thrusters, using hydrazine (N2H4) and dinitrogen tetroxide (N2O4) as fuel and oxidizer, respectively.
> The other kind of thruster on Webb is called a MRE-1, or mono-propellant rocket engine, since it only uses hydrazine. There are eight MRE-1s on Webb, and they are used for attitude control and momentum unloading of the reaction wheels
Ref: https://jwst-docs.stsci.edu/jwst-observatory-hardware/jwst-s...
The point of sitting in a lagrange point is that you can stay there without moving due to two gravitational forces. That's not perfectly accurate, but I don't think it needs constant thrust, just occasional taps.
It does have thrusters - a ring of 16 hydrazine "burning" units that can produce thrust on 3 axis.
The fact that the L2 point is unstable and that thrusters are required puts a lifetime on the telescope - I think NASA plans for a minimum of 5 1/2 years and are hoping to get up to 10. That's entirely reliant on the fuel supply.
The use of thrusters does impact the sensors the telescope uses. NASA et al schedule usable telescope time around burns, and general attitude shifts/correction. The telescope uses a bunch of gyroscopes/flywheels to point itself in the proper direction, during maneuvers like that the sensors aren't operable.
So when the fuel is exhausted the orbit decays and the unshielded telescope disintegrates on re-entry into Earth's atmosphere?
Or drifts off into its own orbit around the Sun, but essentially yes.
I think more accurately it will go around the sun once per year. The earth will provide the extra gravitational pull (toward the sun) needed to orbit the sun at a larger radius than the earth in the same amount of time as the earth.
Normally, objects with smaller orbits take less time to make a circuit. But this is placed where the earth's gravity pulls it back, just enough to make it take one (earth) year to finish its smaller orbit. So gravity from the earth and the sun are involved.
Maybe "co-orbits the Sun with the Earth using Earth's gravity"
And if you bring astronauts close, then I guess that some EVAs in existing suits starts looking appealing vs developing those remote hands.
Citation needed