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Comment by DiogenesKynikos | Hacker News Reader

The future of astronomy is both on the ground and in space.

There are so many things that you can only conceivably do from the ground. You can build vastly larger telescopes on the ground, you can install far heavier instruments (like cameras and spectrographs) on them, you can upgrade and repair components much more easily. You can build massive arrays of radio telescopes. You get the point.

There are some things you can only do from space, or that are better in space, but saying that everything will be done in space is like saying we only need laptops and don't need datacenters. You need both.

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Are there really a lot of ground based telescope components larger than Starship's fairing?

I'm just not seeing the argument for there being any telescope function that wouldn't be better done in orbit, at Starship payload prices.

Yes, though I guess it depends on what you mean by lots: https://en.wikipedia.org/wiki/List_of_largest_optical_reflec.... Critically the 30+m monsters under construction have only recently become feasible on the Earh let alone in space, and much smaller instruments still provide significant value today.

There’s a much longer list of large radio based telescopes which have minimal advantages in space to the point where we haven’t launched any, and they are also negatively impacted by constellations. Also, several types of observations don’t really benefit from being in space. If you want to track killer asteroids space doesn’t provide much advantage even if you could get there for 100$/kg.

IMO the issue here isn’t satellites, it’s that they can harm multi billion dollar investments at zero cost to themselves. If you’re very clearly causing 10’s of millions in damages you really should be compensating the people affected.

> There’s a much longer list of large radio based telescopes which have minimal advantages in space to the point where we haven’t launched any

What if they could be put behind the Moon, completely shielding them from Earth RF emissions? It's been a cost-prohibitive idea now, but might not be for much longer.

The largest filled-aperture radio telescope in the world has a 500-meter diameter, and reportedly only cost $180 million. For comparison, the International Space Station costs $3 billion per year just to operate. Doing stuff in space is expensive.

Right, but the whole reason people are so excited about SpaceX is because they're making the costs of doing stuff in space drop like a stone.

For large (>10m) telescopes, it doesn't matter much, because no one is building rockets with big enough fairings. Even if the cost of launching to LEO was $0, in-orbit unfolding/assembly is a bottomless hole of engineering complexity that you cannot avoid. Again, see JWST/ISS.

I count 13 on wikipedia's list of the largest telescopes. There are 3 more currently under construction. The evocatively named "Extremely Large Telescope" is estimated to cost about $1 billion USD. Who knows how much it will actually cost, but for comparison, that's about $400 million less (adjusted for inflation) than the budgeted cost of the Webb telescope, which is about 1/6 the planned size (and therefore 1/36 the light collecting capability).

edit: italicized above. The Webb ended up costing $10 billion, so the savings could be even larger

But the point is that Webb was vastly over-engineered because we needed to get value out of every ounce of mass at the very high costs of legacy launch providers, and even more compromised because of Ariane 5’s tiny fairing.

You could build Webb for vastly, vastly less money if it launched on Starship, not just per unit of mass; volume is at much less of a premium in the new regime.

You can’t quite fit ELT pre-constructed into a single Starship, it’s true. But it’s built out of segmented mirrors. It doesn’t have to arrive on station in one piece.

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