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Hubble Space Telescope is a marvel of astronomical tools - particularly judging by how much it moved the science. It took a lot of fixes along the way, which certainly prolonged its useful life.

Its successor, James Webb Space Telescope, is going to be a significantly better tool. However, it's going to work only for a handful of years, and the reason is "we can't service it" (e.g., to replenish supply of liquid helium). It's going to sit in Earth-Sun L2 libration point, just a few times farther away from Earth than the Moon.

Why we can't service JWST with modern generation of spacecrafts able to fly farther than the Moon? Orion in particular could be a good candidate. Equip it with a propulsion unit - which would cost another launch of a heavy rocket and docking on LEO - and a airlock, which is relatively lightweight and cheap, and you can fly a few weeks mission. Similar capabilities are reachable by other spacecrafts (even with Soyuz, though I doubt it will logistically work to modify it for such an unusual mission). In exchange we'd get longer mission for such a unique tool as JWST promises to be.

Space Arris
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    I think there are two parts to this; the servicability of the JWST (I don't think it was built to have bits replaced) and getting there in an Orion spacecraft – Dave Gremlin Apr 06 '19 at 19:53
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    I doubt you could do this mission for less money than building and launching a JWST replacement. – Eugene Styer Apr 06 '19 at 20:29
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    Because "Orion" is just an imaginary headline for covering up a multi-billion fraud in the accounting of NASA. Orion was never intended to, and will never, fly. (This might not be apparent to everyone right now, but do check back ten years from now to see that this is true!) – LocalFluff Apr 06 '19 at 22:32
  • I don't think the logistics of servicing something at L2 has even ever been seriously considered. You need a ton of fuel leftover to maneuver there, and get back, not to talk about that you have to take all your life support systems with you (which should be more than an Orion capsule). – AtmosphericPrisonEscape Apr 06 '19 at 23:20
  • Have a look at all the answers to The JWST - What happens if/when it breaks? as well as Besides HST, JWST and stations, are there any examples of satellites designed for service in space? – uhoh Apr 07 '19 at 00:08
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    @LocalFluff "never suspect malice when incompetence will answer" – Organic Marble Apr 07 '19 at 00:41
  • I'm not convinced that the Hubble service missions made any sense, economically speaking. The telescope initially cost 1.5 billion, and each of the 5 service missions cost another 0.5 billion. So for the same price we could have sent 2, maybe 3, full non-serviceable telescopes... – asdfex Apr 07 '19 at 09:41
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    @LocalFluff - The blame for this fraud lies more with Congress than with NASA. A better way to look at it: Orion (along with the SLS) is a multi-billion fraud in the accounting that Congress has foisted upon NASA. – David Hammen Apr 07 '19 at 09:43
  • @asdfex agreed. When we have even basic autonomous manufacturing and assembly in orbit, then I’d like to see more efforts towards making telescopes serviceable and upgradeable - until then, our capabilities just aren’t robust enough. – Snoopy Apr 07 '19 at 16:04
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    @asdfex There is much, much more at play wrt the human conquest of the Solar System than mere economics. The Hubble program has demonstrated this in spades by reminding NASA that the element of human drama (evident during the various servicing missions) has the potential to greatly increase public taxpayer support of space exploration! – Digger Apr 09 '19 at 16:34

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James Webb Space Telescope Program Scientist Dr. Eric Smith spoke about this on TMRO recently. The main reason is that the telescope wasn't designed to be serviced so it is not as modular as Hubble and systems are integrated throughout the telescope rather than being discrete units that can be removed and replaced like on Hubble. It was designed like this from the beginning because they knew it would be at L2 rather the LEO where it would be much more difficult to service.

That being said they did include optical targets on the bottom of of the telescope where the fuel ports are so a mission in the future could potentially come and refuel it. I don't know if that is something that Orion could potentially do but I wouldn't think a manned mission would be required for a refuel and if it's not manned why use Orion.

Head Pancakes
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  • Accepted. At the same time the main limitation on the service life is said the helium limit, which should be relatively easy to transfer. And not being modular could be actually harder to achieve (modularity allows, for example, parallel development and less dependencies of systems on each other), even though it's more optimal for size and weight. Would be interesting to learn about development process of JWST in another thread. – Space Arris Apr 07 '19 at 15:29