Behold, the Ultimately Large Telescope: A revived proposal for a 100-metre liquid-mirror star scanner on the Moon
- Reference: 1605697333
- News link: https://www.theregister.co.uk/2020/11/18/moon_ultimate_telescope/
- Source link:
Specifically, the academics, based at the University of Texas at Austin, propose erecting the instrument – dubbed the Ultimately Large Telescope (ULT) – at a lunar pole to collect light from stars that existed before galaxies had even formed. The mirror could be made of a liquid salt, which would remain fluid in the cold environment, and would be easier and cheaper to transport to the Moon than glass. The mirror would also have a reflective layer of silver.
"The mirror base would be made out of a liquid that does not freeze at -145°C, or -225°F, corresponding to the temperature of the Moon," NASA Hubble Fellow Anna Schauer, who led the proposal work, told The Register . "Previous experiments in 2008 found ionic liquids, or 'liquid salts,' to be the best candidates. The layer of silver coated on the mirror would be very thin, only a few tens of nanometres thick."
"Any extra-terrestrial telescope would be expensive," she added. "The liquid mirror technology promises significant savings, compared to the standard architecture of big telescopes based on solid structures, perhaps reducing cost by a factor of ten, or so. In rough numbers, an approximate estimate is a few hundred million dollars. The final price tag will also depend on the other infrastructure that might exist on the Moon by then, such as the planned Artemis permanent lunar base."
[1]
The proposed star scanner on the Moon ... astronaut for scale. Source: Roger Angel et al./Univ. of Arizona. Click to enlarge
The instrument would study the first suns born in the universe some 13 billion years ago. Classed as Population III stars, they’re massive: at least 300 to 1000 times more massive than our Sun. These ancient objects are difficult to study, though; their light is faint and redshifted. Today's telescopes are incapable of studying these faraway stars, and you'll need something on the Moon like the ULT to get a better look at them, the university team argued in a paper proposing their design, which is to be published in the upcoming issue of The Astrophysical Journal
[2]preprint version
.“The launch of the James Webb Space Telescope will open up a new window for observations at the highest redshifts," the paper stated. "However, even with this new facility, the first stars will remain out of reach, as they are born in small minihalos with luminosities too faint to be detected even by the longest exposure times.
"In this paper, we investigate the basic properties of the Ultimately Large Telescope, a facility that can detect Population III star formation regions at high redshift. Observations will take place in the near-infrared and therefore a Moon-based facility is proposed."
Did Arthur C. Clarke call it right? Water spotted in Moon's sunlit Clavius crater by NASA telescope [3]READ MORE
The mirror must spin continuously to keep its shape, and it would operate autonomously, powered by solar energy, and relay its scans of the heavens to Earth via satellite. NASA [4]toyed with a similar idea in 2008, though it never came to fruition. "We are putting this idea out to the scientific community and hope to revive the discussion about it," Schauer said.
“We live in a universe of stars,” [5]added Volker Bromm, co-author of the paper and an astronomy professor at UT Austin. “It is a key question how star formation got going early in cosmic history. The emergence of the first stars marks a crucial transition in the history of the universe, when the primordial conditions set by the Big Bang gave way to an ever-increasing cosmic complexity, eventually bringing life to planets, life, and intelligent beings like us.
“This moment of first light lies beyond the capabilities of current or near-future telescopes. It is therefore important to think about the ‘ultimate’ telescope, one that is capable of directly observing those elusive first stars at the edge of time.”
NASA supercomputer modelling Artemis mission gets an AMD boost
In other Moon-related news: HPE is expanding the processing power of NASA’s [6]Aitken supercomputer , which is being used to simulate rockets during liftoff for NASA’s Artemis mission – an [7]ambitious effort to send the first woman and next man to the Moon by 2024.
The super was built using Intel Xeon Scalable parts, and it has a peak performance of 3.68 petaFLOPS. Now HPE is adding 7,742 AMD Epyc microprocessors, allowing it to reach 4.72 petaFLOPS, we’re told. The upgraded machine will be ready for use in January 2021. ®
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[1] https://regmedia.co.uk/2020/11/18/telescope.jpg
[2] https://arxiv.org/abs/2007.02946
[3] https://www.theregister.com/2020/10/26/nasa_moon_water/
[4] https://science.nasa.gov/science-news/science-at-nasa/2008/09oct_liquidmirror
[5] https://mcdonaldobservatory.org/news/releases/20201116
[6] https://www.hpe.com/us/en/newsroom/press-release/2020/11/nasa-unveils-new-research-progress-for-human-mission-to-the-moon-with-supercomputer-powered-by-hewlett-packard-enterprise.html
[7] https://www.theregister.com/2020/11/13/nasa_oig_moon_2024/
[8] https://whitepapers.theregister.com/
Re: liquid?
Inconsistent viscosity might cause imperfections in a frozen surface which may not be as big an issue when it's a liquid in motion. Presuming that the "thicker" parts of the liquid would be held against the outside edge by the spin.
(I'm not an expert by any means, that is just my guess and could very well be wrong)
Re: liquid?
I'm also no expert, but Shirley changing the state from liquid to solid means fundamentally altering its underlying physical structure.
Would that be significant?
Re: liquid?
I'd go with yes, there's probably enough of a difference to require a collector design change.
Liquid mirrors do have the benefit of being very easy to clean when they accumulate surface dust (or micro-meteor impact) - drain, filter, replace.
Re: liquid?
> drain, filter, replace.
This one is said to also have a silver layer, which you would have to replace. Using mercury would avoid that, but it would freeze solid at the lunar south pole temperature, unless heated.
Re: liquid?
There are probably huge engineering advantages in the mirror being liquid, but the big problem is you'll have to point the whole moon towards whatever you'd like to look at... Or resign yourself to only studying whatever your telescope accidentally point to, and only for as long as it does.
No specialist, but that seems like a huge limitation to me, especially for the kind of money required to build and run it.
To scale, or not to scale?
If the astronaut in the picture is to scale against a telescope described in the text as being 100m in diameter, then he's a lot bigger than most people.
Re: To scale, or not to scale?
perhaps he was born on the moon and is indeed much taller ....
Re: To scale, or not to scale?
Na'vi
Re: To scale, or not to scale?
It's almost as if you've never seen someone with four metre wide hips standing on two legs wearing a spacesuit before.
Ultimately Large Telescope
So this will be the last definition of 'Large' when applied to telescopes?
Re: Ultimately Large Telescope
More sense than stupid elitist Moon or Mars bases?
Sounds like named by Douglas Adams or Terry Pratchett.
I think it's a good idea.
Re: Ultimately Large Telescope
Nah, we'll work up from that to the Bloody Enormous Telescope (BET), The Fuck Me That's Seriously Big Telescope (FMTSBT), and on through several more, probably including the Is That A Telescope In Your Space Suit Or Are You Very Pleased Indeed To See Me Telescope (ITATIYSSOAYVPTSMT).
Maybe.
This is why I like ElReg
Normally I don’t bother reading the links to sources provided as I’ve come to trust the quality of the reporting here, but today being quiet and having an abundance of spare time I followed the link to the published paper, I read it, twice.
But understood very little of it.
Thanks for summing up and “translating” an interesting idea that mere mortals can understand.
Bravo & have a pint!
Re: This is why I like ElReg
"today being quiet and having an abundance of spare time"
Fancy giving me a hand? I'm snowed under!
Ultimate cost
The Ultimate Costly Telescope should be a more apt name.
I believe the eventual price tag will be more in the multiple billion dollar range, only off by an order of a magnitude, but who's counting.
Re: Ultimate cost
I propose a more affordable version which shall be called the Penultimately Large Telescope.
Build on site?
How many Starship loads would be required to construct a mirror fabrication site on the moon?
Alternatively send a couple of East European builders up there to excavate and line a concave hole then line it with Bacofoil (other foils are available)....
In other news..
The super was built using Intel Xeon Scalable parts, and it has a peak performance of 3.68 petaFLOPS. Now HPE is adding 7,742 AMD Epyc microprocessors, allowing it to reach 4.72 petaFLOPS, we’re told.
That's a hell of a lot of processing grunt to Kerbal Space Program...
Shot to the Moon
I don't get why there are no more missions toward the Moon. Being (relatively) close, it is 'easy' and fast to send a rocket to there. Why is there no mission to test automatic rovers with advanced capacities, to discover what the lava tunnels and caves look like, to experiment 3D printing to built housings, to install telescopes (traditional ones)... Shouldn't be the Moon an experiment field before Mars?
Re: Shot to the Moon
Because landing and moving around on the moon is easy - compared to Mars, so you don't learn much
If you just want to test that the robots work autonomously you can do that in a deserted bit of Earth
Re: Shot to the Moon
AFAIK, the Moon is closer to Mars environment than the Earth is. For instance, Earth is protected from solar and space radiations, Moon is not, Mars just a few. Earth conditions make cooling easy, it's much more difficult on the Moon with no atmosphere or on Mars with its very tiny one. If something works on the Moon, it will work on Mars.
If the final goal is to colonize Mars, let's start with the Moon. Experiment rovers able to build shelters, or to dig and extract water, let's be more innovative! It's just a 3 days trip, not a 9 months every other year.
There are planned Moon missions
Some of them have [1]funding . The Artemis program includes robotic landings. Some time next year we will find out if politicians are still willing to spend tax pays' money on it.
[1] https://en.wikipedia.org/wiki/List_of_missions_to_the_Moon#Funded_and_under_development
Shit Moon Idea
Why don't we railgun all of Earth's shit to terrform the moon? We'd have an abundance of shit, which when added with potatoes and mined moon water, would create an atmosphere we could protect using a magnetic field. We should set it up as a penal colonoscopy I mean colony, until such time the Moon isn't so shitty.
These days, large optical telescope mirrors are made by assembling smaller hexagonal mirrors in an array. I'd have thought doing something like that in space would be far more practical than spinning a large blob of liquid salt.
The surface profile of a telescope mirror has to be accurate to 1/10th the wavelength of light that you're observing. I'm sure they've looked into the practicality of achieving that, and I presume the Moon's gravity would naturally yield the desired shape (something like a parabola). But how would you steer such a thing to look anywhere but straight up?
liquid?
Why not make it out of something that *will* freeze...
Then you can heat it (solar power), spin it, let it freeze and have a pointable 'scope...