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Comment by brucethemoose2 | Hacker News Reader

> likely to be more than $100 million annually

Oof.

Should the US have just partnered with Europe? Seems like a bigger telescope would have been better than two individual projects (with one struggling significantly).

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ELT is in southern hemisphere, TMT will be in the nothern. Just one cannot see the whole sky. So it's valuable to have both.

It does make me wonder where that sort of money goes. That's roughly $275k per day.

At $1k per person per day you can have 75 staff doing whatever they do (maintainence etc) and still have 200 left over. Computers? One would have thought they'd have on-site processing as part of the build cost. Electricity to run said computers? Food for the cafeteria?

Presumably we can ignore accounting things like depreciation.

Not that it matters I'm sure it's expensive to run, it's just that $275 k per day seems like a lot...

The ESO observatory in Paranal has its own electricity power plant, both natural gas and - recently - solar.

Computers: multiple TB of data per day will be generated and will need to be archived, backed up, and made easily accessible. Everything on the telescope and the instruments mounted on it is computer-controlled, with countless computer and electronics racks to power and maintain.

Staff: not only salaries and food, they have to run a whole hotel-like facility for people who live on the site for weeks at a time, plus travel costs both from the rest of Chile and from the main HQ in Germany. It's in the middle of the most forbidding desert on Earth, so water and everything else has to be trucked in. Facilities are spread out, so there are dozens of trucks and cheap Fiat cars to go around, with a gas station to fill them up. Cooks, cleaners, engineers, technicians come and go nearly every day.

It all adds up quickly.

The Tom Scott video linked else where in this thread shows that the existing 4 telescopes have on-prem facilities to resurface the mirrors with a layer of 99% pure aluminum 1000 atoms thick. I'm guessing that quality material fabricated to be installed that precisely is not cheap. The mirrors are moved around on custom built hover crafts. When the 4 scopes are used at the same time, the "plumbing" to get the lights to the instruments at the same time is so precise, it is measured in nanometers.

There is nothing about these facilities that is normal off the shelf components. Everything will have a cost associated that reflects that. What ever back of the napkin math you are attempting doesn't even come close to being accurate.

The person you are replying to is asking about operating costs, not manufacturing costs.

Resurfacing is an operating cost it needs to be done periodically.

I'm going to need some more info on that, because that doesn't sound right to me.

There's no way they are regrinding and resurfacing the mirror periodically - cleaning, sure. But redoing the surface? I'd like to see more info please.

Just go watch the referenced link. It is a very informative video. It's only the top response of this whole thread, but just to make it convenient[0]. I can only lead you to water. I can't make you drink it. Continuing to refute it after that just let's us know exactly what you're about

[0]https://news.ycombinator.com/item?id=38092084

As requested, I drank, and I saw the part about them refinishing the top surface layer. As I suspected it was not them redoing the glass, rather removing the aluminum and redepositing it.

The perfectly shaped glass is the expensive part - coating it is not the expensive part. So despite drinking, I did not get my answer on how this telescope costs $100million a year to operate.

Well operating a highly custom and very expensive is going to have astronomical operating costs as well.

What part of my comment suggests I was talking about manufacturing costs?

This part: "quality material fabricated to be installed"

But they do this operation every few years. It is an ongoing process of installing the aluminum surface. Applying/Re-applying maybe words better fit for your understanding?

It's nice to change your words after the fact, but taking your words, as originally written, your response to a question about operations was a reply about manufacturing.

Additionally it does not costs millions to operate this resurfacing machine. Building it? Sure, I could see that. But running it? No way.

275 k if you average it out over the year, but things like a mirror replacement will require a lot of work, companies, materials and people.

Think also of the data processing, and how much money your employer funnels to AWS.

I don’t think these two telescopes are interchangeable. Pretty sure the Webb telescope was designed for seeing specific light spectrums.

There might be enough use demand to saturate multiple gigantic telescopes. The US should fund at least one as well.

Technically a bigger telescope has more throughput, right? It can expose the same spot for less time, then move onto the next observation.

Generally there is a lower bound because it takes a few minutes to slew to a new spot on the sky and stabilize. Very large telescopes are slower, so this will take longer, possibly 5--10 minutes. So you typically want to spend at least 20 minutes per target so that most of your time is spent observing rather than slewing. That's why there's still a lot of demand for 1-m class telescopes.

There are also issues with saturation. Large telescopes simply cannot observe brighter targets because they saturate the detectors too quickly. (This is not so much of a problem for deep field objects since none of them have high surface brightness anyway, but can be a problem for brighter stars.)

Only if it were completely automated, or run by the full–time staff instead of by visiting astronomers. Plus, even if a new telescope is 10× better than the old one, nobody will agree to observe for 1/10th the time; it would negate the advantage of the new scope.

I don't remember where I read it, but I'm pretty sure proposals to directly image exoplanets rely on pointing multiple telescopes at them simultaneously. So this might be ok.

The biggest win would be to convince the NRO to flip some of their telescopes 180 degrees

I'm sure the spy sats could take some pretty pictures, but I doubt you can get much science done with their image sensors.

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