TMT construction begins Monday 15 July

[HereOnThePrimalEdge]

I suspect the basic infrastructure issues aren't so much of a concern for the CCP.

A high speed rail line opened to Tibet some years ago.  The Chinese could probably build a branch line.  Not sure if cost would even be considered as they construct 6 lane highways no one drives on and clusters of 20 story apartment buildings that sit empty. 

But as TomK noted, dry and dark alone don’t cut it.  I’m not sure where this proposed site is as compared to the route Heinrich Harrer trekked during his Seven Years In Tibet (also a movie recommendation) but he encountered plenty of storms, high winds, etc. while avoiding bandits, the military, and insanely vicious dogs.  Tibet is a huge country with plenty of variables in weather however.

There was also a proposed observatory site in India discussed on Punaweb as an alternative for the TMT, but the details were daunting.  I don’t believe any other telescopes have been proposed there in the meantime.

I’ve been looking at world weather maps this last week because many people I know are experiencing 90-100 degree temps on a daily basis.  Hawaii has the best weather in the world.  And that’s generally the case on a year around basis.

[TomK]

For those interested, there is a Nature paper I found on astronomical site monitoring on the Tibetan Plateau. I haven't had a chance to read it carefully, I've just skimmed it, but I posted it so anyone who wants to can read it. My quick opinion is that it looks a decent enough site, certainly not as good as Mauna Kea or Chile, especially for natural seeing and the number of clear nights, but my first impressions are it would be a good submillimeter observing site and certainly usable for optical/infrared telescopes (much more than, e.g., the Canary Islands).

https://www.nature.com/articles/s41586-021-03711-z

I also wonder what an international organisation would think about the site, given that politically, China and Tibet have a bit of a history.

[HereOnThePrimalEdge]

ground-based telescopes can do the job of the JWST or Hubble for a much lower cost and can be maintained and upgraded.

As TomK mentioned above, ground based telescopes can be maintained.
An example of attempting something as (relatively) simple as raising the orbit of a space telescope is happening right now.  The satellite that was launched for the rescue mission is spinning out of control, even before it could reach the Swift Telescope.  Hopefully they can still recover control and complete the mission.  Stay tuned.

If it was a problem on a Mauna Kea telescope, you drive a truck and repair crew up there.

https://arstechnica.com/space/2026/07/re...-in-orbit/

[Durian Fiend]

ground-based telescopes can do the job of the JWST or Hubble for a much lower cost and can be maintained and upgraded.

As TomK mentioned above, ground based telescopes can be maintained.
An example of attempting something as (relatively) simple as raising the orbit of a space telescope is happening right now.  The satellite that was launched for the rescue mission is spinning out of control, even before it could reach the Swift Telescope.  Hopefully they can still recover control and complete the mission.  Stay tuned.

If it was a problem on a Mauna Kea telescope, you drive a truck and repair crew up there.

https://arstechnica.com/space/2026/07/re...-in-orbit/

Our telescope expert in residence has the following to say about this:

"You might recall that I've mentioned many times on PW that I didn't believe the TMT would ever be built on Mauna Kea. My opinion was always based on politics, not science, because it's obvious Mauna Kea is the best place for the TMT. If it moves to another site, it will lose ~30% of its capability (i.e., mid-infrared). 


The JWST is doing some fantastic work in space but has a limited lifespan and, unlike the Hubble, cannot be repaired or refueled; it's a one-off project that will eventually just float around in space. Before that happens, the ELT in Chile will be matching and likely outperforming the JWST. The TMT would have been doing the same if it were being built on Mauna Kea, but that didn't happen and certainly won't be competitive as a mid-infrared telescope compared to the JWST and the ELT.

There is now a very generous offer from Spain to pay a large proportion of the costs if the TMT moves to La Palma in the Canary Islands. I don't know how realistic it is that this will happen, but it wlll be hard for the TMT partners to ignore. 

https://www.techtimes.com/articles/322067/20260729/spain-bids-11-billion-win-thirty-meter-telescope-away-mauna-kea.htm

There are a lot of decisions the TMT partners will need to make. Give up on Mauna Kea? Take the loss of 30% of its scientific potential? Keep fighting a losing battle to build on Mauna Kea?"

[HereOnThePrimalEdge]

The 30% is just an estimate. I don't know how astronomers will use the TMT if it's built in La Palma. The site is not high enough to observe efficiently beyond a wavelength of around 2.3 microns (that's the upper limit for what's called the "near infrared". Water vapor then starts absorbing infrared radiation beyond that wavelength, then methane kicks in around 3.3 microns, and CO and CO2 also kick in, meaning there are discrete wavelength regimes you can observe the sky but they involve complicated observing techniques to carry them out. The longer the wavelength, the more the sky background caused by our atmosphere increases to the point where the sky is much brighter than any object you want to observe, sometimes hundreds or thousands of times brighter.

You can overcome this by certain observing techniques which are only possible at the driest observing sites: Mauna Kea, some places in Chile and the Antarctic. The idea is to continually "chop" your secondary mirror, i.e., move it between two positions at ~10 Hz while also "nodding" the telescope every 10 or so seconds. The time varies depending on the type of observation, but those are typical times.

At La Palma, you won't be able to do that because you're looking through too much atmosphere and the mid-IR light from the target will be absorbed by the atmosphere no matter what you do. It's why the JWST is so special; it's carrying out mid-IR observations and has no atmosphere to worry about. Another issue is that because the sky is so bright, your infrared detector will become saturated by the sky in milliseconds, so you have to use very short exposures, take many of them, and then make sure you can time those with the frequency of the secondary mirror chopping at ~10 Hz. Technically, it's very complicated and challenging but very rewarding when you get it to work!

The next question is: why do you need to observe in the mid-infrared? Well, if you want to observe stars being born, those are the wavelengths that penetrate through molecular clouds in space where stars are formed. Measuring the brightness of objects at those wavelengths tells you their spectral energy distribution; therefore, their temperature and the environment they are in. Given the expansion of the universe, the emission of hydrogen lines is sometimes shifted into the infrared due to the Doppler effect. Mid-IR observations also allow observations of colder objects such as brown dwarfs and exoplanets. Finally, most of the complex organic molecules that indicate life have spectral features that are in the mid-infrared, so you need to be able to look beyond 2.3 microns for those molecules.


Swift rescue mission update:
Spin rate of rescue satellite has been cut in half.
https://arstechnica.com/space/2026/08/he...t-mission/

[HereOnThePrimalEdge]

Space telescope rescue mission failed.  Telescope will burn up in earth’s atmosphere later this year.

Space is hard.  Earth has repair vehicles and roads.  Mauna Kea has functioning telescopes with working life spans that can easily be extended.  

https://www.space.com/space-exploration/...cope-fails

[kalakoa]

Easier to repair telescopes in space than to deal with a self-declared "nation".

[MyManao]

Space is hard...

So? 

There was a day when there were no telescopes atop MK. No road, and only a vision there should be.. and man that frickin' mountain was a mean one to settle. But someone had a vision.. and a jeep.. and a little dome was put up.. and look what followed.

Equally, there was a day when there was no way to put a boat into the coastal waters of the island along the south flank of Kilauea, and I am sure there were hurdles to getting that third class boat ramp at Pohoiki..

Everything started.. was hard at first.. and overcame whatever obstacles to become second nature. But when they do that doesn't mean, never has ment that we stop there.. life is good lets go to the beach. Pau. No Edge, it usually means how can we do it even better.

You have harped on this a road to it is better than an orbit with an unobstructive view for a good long time.. and still it is the same as the guys down south holding on to their good ol' boat ramp against all the better boat ramps with so many more amenities, with easier access and long term berthing. And still, for all your clinging to you have gotten exactly squat in return. just like the guys with their boat ramp.. you're mired in quicksand.

The future is always a bitch. Though folks like Steve Jobs never thought so.. that Nazi white boy from South Africa doesn't seem to think so.. and you even drive an EV.. because of it.

Man is going to space.. every single step of the way has been fraught with reasons not to for those that think things are easier otherwise. I mean, come on man, we have telescopes on MK so why do we need to actually go there?

Eventually the planet will be ringed with telescopes. There will be a network of 24/7 views in every direction.. live on the internet. Why wouldn't there be? Eventually folks will book vacations on other celestial bodies. 

But then you got a Kia, maybe that's enough. Maybe we should give up on holidays on the moon.. and build telescopes on Earth so we all can look at the place and imagine.. after all, that's a lot easier. There's a road to it..

[HereOnThePrimalEdge]

Everything started.. was hard at first.. and overcame whatever obstacles

Yes, that’s true.  But not everything was overcome by sheer grit and determination.  Some projects required grit, determination, money, and an advanced level of technology.  For instance, the US Army had a plan in 1962 (Project Horizon, you can look it up) for a 12 person moon base.  To be constructed within a few years of that date.  65 years and still no moon base.  It will happen, but obviously the time was not right, our scientists, legislators, service members, and society weren’t ready.  

Sci-fi wishful thinking on Punaweb won’t bring space based telescopes into existence any faster than they are currently planned.  In the meantime, do we have the technology to repair space based instruments? No.  Do we have a mountain, a road, and technicians who can travel and work without the requirements of a rocket and spacesuit? Yes.

You can wax poetic in paragraph after paragraph about our future (without also providing a realistic timeline), tell us how beautiful the imaginary space telescopes will be, how many will ring the planet, but it’s still only pie in the sky.  Sure, you can make an AI slop image of the pie up there and tell us how BEAUTIFUL it is, even LOW CALORIE!  That’s because it doesn’t exist.  

Meanwhile, mountain based telescopes are still making real discoveries every day.  Come back down to earth, and breathe in the oxygen while you’re here, slow, deep breaths.