The Hubble and James Webb Space Telescopes have astounded with cosmic images, but a new era of Extremely Large Telescopes (ELTs) is emerging. With mirrors up to 39m in diameter and advanced optics, ELTs promise 100 times Hubble's light-gathering power. The European Southern Observatory (ESO) aims to complete the 39m European ELT in Chile by the decade's end. The US projects, Giant Magellan Telescope and Thirty Meter Telescope, face funding challenges, prompting a call for the US National Science Foundation to lead and consolidate efforts into a single ELT project.

So there doesn't seem to be any 'risk' as all projects are going ahead just fine. Well except Hawaii but that's not a new problem.

The space based platforms are also not at any risk, they still have capabilities the land based ones will not have such as the ability to see wavelengths absorbed by the atmosphere, weather independence and the lack of satellite interference.

Hubble is going to require a reboost and perhaps even a maintenance mission some time within the next decade, so that's a very real risk to that mission ending. I hope we can figure something out. At this point, I argue even just keeping Hubble flying is a great boon for space exploration advocacy.

Otherwise though, I agree there isn't any "risk" insofar as anything hitherto unseen. Science projects fighting for funding is nothing new and positively mundane.

Wouldn't it make sense to allow it to decay and spend the money on something more modern? Optical sensors have had great advances in the meantime, the original Hubble lenses were wrong and a correction had to be installed, and the cost to put something in low orbit went down a lot.

Also we have better understanding of the failure modes of gyro bearings so we can build them to be less failure-prone (someone more knowledgeable please correct me if I didn't get this right).

The original solar panels must have degraded quite a bit by now, so you'd eventually have to replace those too - overall it doesn't feel cost effective to keep fixing the thing.

>Wouldn't it make sense to allow it to decay and spend the money on something more modern?

Objectively speaking? Yes, money would be better spent developing and launching a newer and better Hubble 2.0.

But remember: This is the Hubble Space Telescope we're talking about here, Hubble has acted as the de facto ambassador of space for many generations of people today. The Hubble Space Telescope is a cultural icon of space exploration, it isn't just a space telescope anymore.

Consider that when the Space Shuttle program was on its final legs, NASA was convinced to fly one last reboost and maintenance mission to the Hubble because it is the one and only Hubble Space Telescope. I personally think it's worth spending money to preserve and use Hubble as long and far as we can.

Valid point but the solution is right in your own post: Just call it Hubble 2.0 and preserve its symbolic value. Spend a little telescope time to repeat a few of its most iconic shots (Ultra Deep Field for example), post them side to side, people will love it and it'll still be Hubble.

> Wouldn't it make sense to allow it to decay and spend the money on something more modern?

It wouldn't. The cost to boost Hubble and keep it around is small. About the cost of an ISS resupply, less than $150M.

The cost to build a replacement? Unbounded. JWST was supposed to be completed in ~5 years and cost $1B. It took over 20 years and $10B.

The cost of boosting Hubble won't impact any replacement we might design.

Yeah and Hubble was based on the keyhole spy satellites of the time and those cost like a billion each.

Of course JWST was a completely fresh design with many inherent difficulties.

Ground-based telescopes have capabilities that space-based telescopes do not. You can build much larger telescopes on the ground, attach much larger and heavier instruments to them, and perform regular maintenance and upgrades. Space-based and ground-based telescopes are not interchangeable, and you need both in the modern day.

The editorial is a little indirect but the funding challenge is the key bit.

What the editorial is saying is that both the currently private projects in US to build the new generation of ground telescopes need government money to be completed but it is unrealistic for government to fund both. Therefore the government should pick one to take over and then make sure it has enough money to be built.

Tom Scott on the ELT in Chile:

* https://www.youtube.com/watch?v=QqRREz0iBes

Another risk to ground-based telescopes: "Bright satellites are disrupting astronomy research worldwide" https://www.nature.com/articles/d41586-023-03610-5

Every mass produced sattelite should have an eye on the away from earth side. Constellations should be telescopes by default

Synching multiple optical telescopes into a single aperture is ... hard. Observatories also have special-purpose instruments behind the glass. Can't imagine those being split into small enough pieces to disperse into a constellation. Also, low LEO isn't great for many kinds of astronomy.

You won't be able to do much astronomy with a smartphone camera mounted to a cubesat, unfortunately. It would be very cool, but not useful.

We're not talking about cubesats and smartphone cameras. The second-generation Starlink satellites are so big they're waiting for Starship to be ready (2000kg each, with solar arrays 20m long [1]).

[1] https://starlinkinsider.com/starlink-gen2-satellites/

And yet there are tech apologists who claim that dark paint, sky size and AI filtering make this a non-issue.

I have much more primitive objections to this. I want an unobstructed view of the universe with the naked eye. I want to know that when I look up I won't have to wonder whether a bright object is an artificial satellite or an object in space. It's bad enough that light pollution has made it impossible to see the universe from cities. The tradeoff of losing visibility of space from anywhere on the planet for the convenience that these things provide is not worth it. Especially when many of them are used for spying and military purposes.

> The tradeoff of losing visibility of space from anywhere on the planet for the convenience that these things provide is not worth it.

You state this as a fact, but this is far from settled. I for disagree with it. Connectivity everywhere is a huge benefit. Having to ignore a few tiny specks of light on the sky is a small inconvenience compared to it.

I'm ok if what you say is your preference, but you might be surprised that not everyone shares it.

> I want to know that when I look up I won't have to wonder whether a bright object is an artificial satellite or an object in space.

Artificial satellites are objects in space.

Also you already have to. We have the ISS which is frequently visible as a fast moving bright dot, then you also have the Iridium flares. Then of course you have airplanes, which are equally easy to confuse with natural object.

> You state this as a fact, but this is far from settled.

It wasn't intended as a fact, but there's an implied "IMO" at the end of that sentence. :) You're fine to disagree with it, but at the same time, those of us who don't like this trend have no say in the matter. It is being imposed on everyone, whether we like it or not.

> Also you already have to. We have the ISS which is frequently visible as a fast moving bright dot, then you also have the Iridium flares. Then of course you have airplanes, which are equally easy to confuse with natural object.

The amount of airplanes in the sky visible at once don't come close to the amount of planned satellites Starlink and other corporations plan to launch in the near future. We're talking about several of orders of magnitude less. And while I also dislike seeing airplanes, at least air transportation is a general public good. We already have pretty good worldwide internet connectivity by ground. Increasing space junk globally so that remote villages without access to water can get online, or for rich people to have slightly better and cheaper connections from their yachts, sounds like a bad deal to me. And this is besides the fact that most of these satellites won't be used for providing internet access, but for the traditionally benevolent agendas of governments and large corporations.

We must build the ELT if only so we finally have a ground telescope that can resolve the lunar landing sites, lol

(it would only be a few pixels but still that's insanely harder than you'd think, no previous other telescope, no gigapixel image can resolve it otherwise)

We already pretty good images of some landing sites.

https://en.wikipedia.org/wiki/Third-party_evidence_for_Apoll...

Only from lunar orbit.

I’ve read somewhere that to see flag sized objects we would need telescope size of entire earth. Not true?

Not true, but you still need a pretty big one. In order to resolve a 50cm object 238k miles away (average Moon distance) at visible light wavelengths you need a telescope with a diameter of 500 meters. In order to resolve some details on such object, say have 10 distinct pixels on it, you need 10 times as much. Since resolving power only depends on the distance between the two extreme viewpoints, you could get away with two separate telescopes separated by 5km. But optical interferometry is extremely hard and, to this day, not very successfull.

Wonderful comment, thank you!

You are ignoring the effects of the atmosphere, which are pretty extreme. For looking through your average backyard telescope (no fancy laser-measured corrections for atmospheric turbulence) you are limited to around 400x. You would need several orders of magnitude more magnification for 50cm objects 238k miles away.

Giant Magellan has several of its 8+m mirrors built while Thirty Meter has been fighting native Hawaiians who are not happy with any telescopes on Mauna Kea. GMT would be the safer bet. Blows my mind that the larger EELT will beat them both to first light.

There’s a bit more to it than that. GMT is further along but its design has many compromises versus TMT. Also, a second ELT in the southern hemisphere is less useful than one in both Hemispheres. The situation for TMT on Maunakea is definitely tricky, but it’s also a better site than either of GMT’s or EELTs.

I've been told (but can't confirm) that the GMT instruments are farther along, as well. I agree that a northern hemisphere telescope is necessary and I'd like to see both get built. I'll defer to others on whether Mauna Kea is superior to the EELT site since Chile hosts a lot of extremely successful observatories.

I like to think I'm sensitive to the wrongs done to indigenous populations but can't come to grips with the Native Hawaiian's protests. Nevertheless, they have worked and there is no end in sight. Isn't TMT still hedging with a backup site in the Canary Islands?

It looks like NSF has to arrange a shotgun wedding between Carnegie and Caltech the way it did with Caltech and MIT over LIGO.

https://www.scientificamerican.com/article/behind-tomorrow-s...

My understanding is that the AO system for GMT is going to pose quite a challenge. A big topic of ongoing research is dealing with “petaling” where the separate primary mirrors in phase due to the atmosphere.

For combining the projects, it does seem like that may be the only option funding wise, but it’s hard to imagine what the resulting observatory would look like. Maybe it would have to be a completely new design?

Thanks for the pointer. I am interested in instrumentation so I'll look up the AO papers. Naively it seems like that would be an issue whether the primary is a few large segments or a lot of small ones.

If the resulting project winds up as a redesign, it would presumably add years to the project and that will only increase costs. Some philanthropic organizations and partner countries will see their generosity go for nothing which won't help matters. EELT will be operational in that time and getting results.

I also wonder about the growing LEO satellite problem. I get that these enormous telescopes have narrow fields-of-view compared to Rubin and similar wide-field survey facilities. The possibility of these being overwhelmed by spaceborne light pollution seems very real.

> like to think I'm sensitive to the wrongs done to indigenous populations but can't come to grips with the Native Hawaiian's protests.

It’s “holy land”. History is paved with mass death and destruction fighting irrationally over specific pieces of land that have nothing more than “societally sentimental” value.

I can understand it better when people have lived in a place, built structures, raised families, and so on. AFAIK, the top of Mauna Kea was not settled that way and in fact, is pretty inhospitable to humans who are not very well prepared to be there. I've never been to Hawaii but understand that rampant development and tourism are big problems on some islands. I could understand knocking down massive hotels and returning that land to nature. The telescopes at least to me are an entirely different situation.

It might be similar to the way there are unclimbed peaks in the Himalaya because the summits are considered holy. For example Kailash is considered holy by several religious groups, and there are pilgrimages to the base of it but there is no record on anyone climbing it. People in Hawaii may have considered the summit holy without building anything up there.

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

That's a good point. Not that it changes my mind about the worth of the telescopes but I can see that the peak could have been left alone by Native Hawaiians for those reasons.

Isn't the exploration of the mysteries of the universe a great way of putting a holy place to use?

If we're going to be making utilitarian arguments, I'll point out that almost everything you own could be put to better use by someone else.

In this particular case of native Hawai'ians, and there's a long history of mainlanders deciding, without asking them, that their stuff could be put to better use by them.

No. You should read "Hawaiian Antiquities" by David Malo, a Native Hawaiian historian who lived during the early Kingdom. He documents what happened on the mountains, and as far as I can recall, he only mentions Mauna Kea to mention an adze quarry that was used. You can also read Liluokalani's book. She mentions sacred mountains, but it's Mauna Loa, not Mauna kea. That's not to say there hasn't been religious significance but that it never stopped things like rock quarrying or hiking, or even the early telescope building.

This idea of the mountain being tabooed for anything but Native Hawaiian religious practices is a recent invention by the Native Hawaiian sovereignty movement in the form of the TMT protesters, as well as a new "sacred" name they cooked up for it "Mauna a Wakea".

It's not just that it's a holy site, it's also that Hawai'i was annexed by the US and its population disenfranchised with most of the land increasingly being owned by rich foreigners and foreign investors. The telescope may be benign by comparison but with growing cultural awareness of Hawai'i's status and history, I'd imagine it's more about the symbolism than the immediate harm. Context matters.

Since statehood, Hawaii has been much more democratic than it was during the Kingdom. Under the Kingdom, a large share of the population was made up of migrant workers without much rights. The initial US takeover was illegitimate, but Hawaii later became a US state with much greater rights for the general population.

It's not simply a holy land, it is also a historic burial site, so it is covered with graves that have historically simply been bulldozed over

The TMT site was chosen because archaeological surveying showed that that particular location does not have any ancient artifacts (such as burial sites).

> I like to think I'm sensitive to the wrongs done to indigenous populations but can't come to grips with the Native Hawaiian's protests.

For me it's especially hard given all indications are they rather recently got to the island themselves.

Of course, these things don't obey logic, so not an argument as such.

[1]: https://en.m.wikipedia.org/wiki/History_of_Hawaii

>I'll defer to others on whether Mauna Kea is superior to the EELT site since Chile hosts a lot of extremely successful observatories.

Mauna Kea is special as a site because it sits in the middle of the Pacific. Their air travels for miles unobstructed before reaching the island, so it flows more smoothly over the mountain. It is also above 40% of the Earth's atmosphere and very dry [1]. This makes for much less distorted viewing than any other telescope site in the world. It is also in the Northern Hemisphere, which has a different sky than the Southern Hemisphere in Chile. The two sites complement each other in this way.

> but can't come to grips with the Native Hawaiian's protests

That isn't surprising. The protest movement, particularly their leaders, are great at manipulating the media. I rarely see balanced articles, or articles telling the real story behind the protests.

The claims of the protesters are ostensibly about the environment and religious sacredness. But most of their claims have been debunked during extensive administrative and legal hearings [2].

What it's really about, particularly for the protest leaders, is Hawaiian sovereignty. They want to restore the monarchy. They are like Hawaii's version of the Sovereign Citizens. But unlike them, the Hawaiian sovereignty movement has its hooks in major institutions, like the University of Hawaii Manoa, the state's flagship campus, where the dean of the Hawaiian Studies school is a pro-sovereignty activist. They are also very good at social media, so many media organizations pick up their media and take it as gospel, without actually investigating their real motivations. This even is true of orgs the Sierra Club, unfortunately.

They are targeting the telescopes because they cannot target the military, a more logical choice with respect to their actual goals, or the tourism industry, because a lot of them make money there. So the telescopes get the knock even though they are the most environmentally and community friendly of the three. They are good at getting attention by bullying astronomy and have even duped people like Jason Mamoa, The Rock, Tulsi Gabbard, and Elizabeth Warren into supporting them. They have all the "woke" college students backing them, even that TMT member institutions (including astronomy students).

The delays in construction that are largely caused by them has caused the project cost to balloon and it's now seeking NSF funding.

1. https://about.ifa.hawaii.edu/facility/mauna-kea-observatorie...

2. https://dlnr.hawaii.gov/occl/files/2019/08/3568-TMT-Final-De...

It might be insightful to see a cost breakdown of these projects

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