I mean, is there something you'd suggest they should have done differently? I'd imagine they gave it as much fuel as they possibly could while meeting all of the other design goals. Is is possible you're more disappointed with the advertising than the observatory itself?
My real concern was the difficulty we had getting the JWT ready. If JWT's successor will also take 20 years to produce, then we better start working on it tomorrow. A 10-20 year lifespan on the telescope would be perfectly fine if we could launch a new one every 5-10 years.
I'm worried that NASA has spent all its money and political will (and then some) getting JWT over the finish line.
Maybe a big infrared space telescope isn't the highest priority to build next compared to other instruments we could put in orbit.
I mean, we'll still have some big terrestrial infrared 'scopes. And we'll be coming off 20 years of very good space infrared scope data... And we'll have had the smaller Nancy Grace Roman Space Telescope up in L2 also (launching in 2027, nominal life 5 years).... ESA is launching an exoplanet-focused infrared scope to L2 in a similar timespan... Presumably other "smaller" infrared scopes will fly by 2042. So...
There's so many wavelengths and different possible space telescope missions. Let's not replace JWST (assuming it gets a normal mission life)-- let's keep some infrared capability and do something else.
Yes, infrared scopes on earth have challenges and are not equally viable for all wavelengths. But VISTA, UKIRT, IRTF, etc, cover a substantial amount of the near and intermediate infrared-- the latter two are high enough to reach into a reasonable amount of the far infrared.
Most of JWST's wavelength coverage is energies that terrestrial telescopes can do (just less well). It's not like Herschel which went into the far, far infrared (and had its life limited by liquid He as a result).
Re: Moon-- Why put a telescope down a gravity well?
Most of the discussion of telescopes on the moon I've heard has been about radio telescopes, where a huge hunk of rock between you and Earth can be a feature.
Roman is slated for launch in 2027 (and survived the JWST overruns!), LISA in the 2030s, and there are a few competing proposals that haven't totally firmed up for the next decade too: LUVOIR, HabEx, and a few others
There are at least four major proposals in the works, including another two IR telescopes, one with an even larger reflector, another with a wide-angle field of view; an x-ray observatory; and an optical + starshield pair (operating at 100k+ km separation) planet-finder. I've just posted in another top-level comment (https://news.ycombinator.com/item?id=29894335)
Further optical and gravitational observatories are amongst further options.
I'd be surprised if other NASA programs weren't nearly as long. Maybe not that long, but heck, I've heard to design a new car at a major car company normally takes 6 years or so, I would imagine a brand new type of one-off space project may take at least 10.
