For one, Starship+Superheavy will enable launching of large objects like space telescopes without forcing object in question to be engineered with expensive, delicate, failure-prone folding mechanisms (like the James Webb Space Telescope was). Just build the thing as big as it needs to be and launch it in its final form (aside from minor folding bits like solar panels).
It could have similar impact on other scientific missions like rovers and probes. The ceiling for what’s possible is much higher when you’re not having to question the worth of every gram and square millimeter.
So JWST has (IIRC) a 6.5 meter mirror once deployed and yes, it was a challenge to develop that tech. Plus it added risk of failure. The Starship Super-heavy seems to have a max payload dimension of 9 meters. I imagine some buffer is required (ie it won't just allow a static 9 meter mirror) but I could be wrong.
So that's larger but not that much larger. Remember the JWST was a huge step up from Hubble's 2.4 meter mirror.
I expect NASA/ESA will take the opportunity to deploy even larger mirror by using the folding tech they've developed.
But here's the main point: these kinds of flagship missions don't support and sustain a commercial launch system. There are only so many JWST 2.0s that you can and will build, launch and deploy. Your bread and butter is going to be commercial communications satellites and other than deploying large constellations like Starlink, I'm not sure what the market is here.
I agree that it you can fold it up, sure, go for a bigger mirror. But widening the mass constraints will also be a game changer.
As for the commercial market, I think it opens up a new branch of materials science for high-end manufacturing by making zero G financially accessible. E.g. growing crystals or perfectly spherical things. If you or I already knew exactly how that would be valuable, we'd already looking for seed investment ;)
Also, let's conservatively estimate its payload to be 50 tons and triple the target launch cost to $30 million. That's $6000 per 10 kgs.
If there's a regularly scheduled flight to Korea/Japan, how many manufacturing and mining operations that are offline for want of a critical part would be willing to pay upwards of $6000 to take delivery of a 10 kilo part in <24 hours when they're losing a few thousand dollars per minute?
Since for telescope what matters is the surface size of the mirror (light collected is proportional to surface which is proportional to r^2), the 9m telescope is ~1.9x better than 6.5m one. This is a big difference. Not even counting the loses from a non perfect alignment of a folding mirror compared to a fixed one.
> There are only so many JWST 2.0s that you can and will build, launch and deploy.
I remember reading about building a virtual mirror out of hundreds telescopes, scattered around Solar system. It will allow getting kilometer-resolution images of Alfa Centaur system planets.
Building and launching that with Superheavy can become viable in the next 30-50 years.
It could have similar impact on other scientific missions like rovers and probes. The ceiling for what’s possible is much higher when you’re not having to question the worth of every gram and square millimeter.