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What material could lenses and mirrors be made off that is not glass.. just so we do not throw rocks up the well

Mirrors can be made out of just about anything: glass, metal, ceramic, polymer, wood, you name it. The mirror itself is just a reflective coating (typically gold, silver, or aluminum), and it can be as thin as a few nanometers. The trick is shaping it and convincing it to hold that shape, which is why we currently use rigid materials like glass and metal. Something inflatable might work, but more likely we'll just stick with lightweight metals like JWST's beryllium mirrors.

However, there's already a lot of rock up there. Asteroids are numerous and big. What's the concern adding more?

Given the reference to “the well”, it’s likely the parent was referring to mass.

Given the hexagonal layout of JWST's beryllium mirrors, future telescopes could 'just' increase the size of the mirror by launching multiple payloads of these mirrors and aligning them in space to form one giant layout. It doesn't seem much of a stretch beyond the complexity and single points of failure NASA managed to hurdle with JWST. How hard can it be? ;-)

Well, the JWST mirrors are made of beryllium

I guess it's not a good idea to lick them.

I was thinking the same thing. The beryllium is just the support structure. It's the coating of gold specifically for the spectrum JWST is built for, so why not coat the beryllium with a different material for other parts of the spectrum?

That's exactly what they do!

https://www.edmundoptics.com/knowledge-center/application-no...

Membrane mirrors show promise:

https://physicsworld.com/a/membrane-mirrors-take-off-for-use...

Are you concerned with glass shattering if hit by orbital junk? If so - impacts at orbital velocities tend to create plenty of debris regardless.

For low-frequency radiation, I wonder if you could build a big and light radio dish in orbit

Why not do something similar to VLA instead. So rather than a single "big and light" dish in orbit, you make a constellation of smaller dishes that equal a single larger dish? We know SpaceX is more than capable of that kind of deployment.

I think the scientists don't think it is worth it.

The reason we need the James Webb telescope in space is because the infrared wavelengths it studies are absorbed by the Earth's atmosphere.

We can observe a lot of the radio spectrum from ground based telescopes

https://en.wikipedia.org/wiki/Atmospheric_window

https://en.wikipedia.org/wiki/Radio_window

https://en.wikipedia.org/wiki/Radio_telescope#Radiotelescope...

> Since 1965, humans have launched three space-based radio telescopes. The first one, KRT-10, was attached to Salyut 6 orbital space station in 1979. In 1997, Japan sent the second, HALCA. The last one was sent by Russia in 2011 called Spektr-R.

https://public.nrao.edu/ask/are-there-space-based-radio-tele...

> There have been a few radio telescopes launched into space over the years, most with the purpose of linking with ground-based radio telescopes to form an array with very long baselines (distances between antennas). One such recent project, which ceased operation just a few months ago, is RadioAstron. I don’t believe that there are any currently-operating radio telescopes in space, though.

One use would be to hide behind the moon to block interference from Earth, at the L2 point in the earth-moon system. Use a laser to, say, a repeater at L4 or L5, and from there further to either LEO or directly the surface.

Going off the challenge that doing that for imaging the black holes was, I figure the limiter is the amount of data generated and the amount of processing needed to put it all together.

That is a fair point, but is that level required to get better data than the VLA but maybe not imaging an black hole? It would be a lot of data to receive via radio especially seeing how the signal being received was radio to start. I'm not intimately familiar with the signal loss from listening under the blanket of the Earth's atmosphere

Lots of smaller dishes get you resolution but not sensitivity. You can image the black hole at center of galaxy, but you can't detect the red-shifted radio waves from beginning on universe.

Also, doing interferometry is much harder when the telescopes are moving.

You say this as if the earth based ground telescopes are not moving either, which is quite confusing since they most definitely are moving.

Not relative to one another

I get it, but even on terra firma, they are having to track relative to each other in 2 axis. In space, they would have to add that 3rd dimension and I stipulate that extra dimension is not linear in complexity. However, tracking on the ground in RA and Dec per object across the distances of VLA is not "simple".

Some telescopes are made using a big spinning dish of liquid mercury.

Yup, these mirrors can only point directly up (zenith telescope). Any adjustment off horizontally to the earth deforms the curve of the mirror. Some liquid mirror telescopes exist today to track space debris. Cheap and useful.

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