x1,000 Resolution of JWST But x1,000 Cheaper

[@melvyndavis2745]

Pleass bring Dr van Belle again and again. He is so grounded, so practical. And a delightful communicator.

[@GerardvanBelle]

Thanks!

[@Kx0195]

​@@GerardvanBelle I love watching passionate, incredibly well-educated intelligent people communicate about their field of expertise and you're at the peak of anyone I've ever watched. I could watch you talk about this forever.

[@thea.m.p.co.467]

Mike Rowe ain't got nothing on @@GerardvanBelle !

[@Robbadobbsoldier]

A scientist with a working microphone isnt easy to find, but Fraser pulls it off. This one was super interesting. You rock Fraser! Great show😊

[@jblob5764]

I mean he claims to not be a scientist all the time. "Journalist not a scientist" so it makes sense

[@Robbadobbsoldier]

@@jblob5764 but I mean that Fraser finds the scientist with a good mic sometimes. Maybe I got lost in translation. Not native English 😂

[@jblob5764]

​@@Robbadobbsoldierohhh that totally makes sense both ways

[@charleslivingston2256]

He says sometimes he decides the audio is too poor and he reschedules after he can send them a better mic

[@Robbadobbsoldier]

@@charleslivingston2256yeah I know. I guess it’s still a struggle. Scientist use 99.9 percent of brainpower on science stuff and only 0.01 on headsets. It’s only the really smart ones who manages to get a good headset.

[@raphaela4149]

Fraser, you are the best interviewer I know of in any field. On top of that it is such an exciting topic and Dr. van Belle is such a wonderful communicator, too. Thanks for your constantly exceptional work!

[@legoseanland1760]

Excellent show! Dude knows his stuff and communicates it well

[@TheArgusPlexus]

When I was a teenager my mom did an internship at Lowell they were super friendly and inviting. They were all too willing to indulge a young kid interested in astronomy, I got to access a lot of areas most people didn't get to enter. It was kickass. The physics dept at NAU was also very inviting. Those psychos had a fuckin railgun in the basement. No reason just because. Awesome city to live in if you're trying to follow physics/cosmology/astronomy in general. Thank you for being so welcoming to a completely unqualified teenager such as myself!

[@jim.franklin]

Fraser, that was an epic interview - He comes over as a really decent guy who just loves what he does and communicating that as clearly and precisely as possible - that is a man who deserves more interviews in the future.

[@kamilZ2]

Great interview, but I wish more info about problems with Lunar interferometer: small field of view compared to the cost, micrometeorites hitting mirrors, cosmic rays hitting light sensors, mechanic wear of movable parts that compensate different distance of primary mirrors to the star, dust covering mirrors.

[@davidmackie3497]

and day/night temp cycling, lunar quakes, .....

[@Greenicegod]

The environment on the surface of the moon, aside from temperature, is very much like anywhere else in space. JWST gets about twice the micrometeorites than you would on the moon, because there's no moon blocking half the sky.

[@kamilZ2]

​ @Greenicegod Rate of cosmic rays is also reduced by half by the Moon. Any data about the rate of secondary micro/nano-meteorites? Without atmosphere and with lower gravity their range is long.

[@benjiunofficial]

Shouldn't be a dust problem because there's nothing to kick it up.

[@Greenicegod]

@@kamilZ2 no idea, but any secondary ejecta will be traveling less than 2.4km/s, the moon's escape velocity. That's an order of magnitude less than normal micrometeorites.

[@RichardBriggs-t2s]

The advantage of 1 big expensive telescope vs lots of cheaper ones is it's safer, or it spreads the risk. I'm so pleased I'm in the JWST didn't explode universe.

[@13tagstar]

My buddy just graduated with his PhD doing research on LISA, the jumbo interferometer that's going to detect gravitational waves. Proud of you, KuyGuy.

[@LongDefiant]

Your friend should go to China. The US is faltering on the telescope research front.

[@gasdive]

I still can't believe that there's not a radio telescope made out of telescopes that are co-orbital with the Earth that has an effective aperture diameter of 2 au. It's 2024 for goodness sake. I also can't believe that the ISS crew in space aren't assembling giant space telescopes and truss structures to hold them in place. Like what are they even doing up there?

[@papaver5]

Wow, thank you so much. I've been wondering the answers to all of the questions for years. Especially every amature putting a combined interferometer together and why we haven't done it. Man, i learned sooo much here. I cant begin to tell you how appreciative i am to you for this interview. Edit: I wrote above after a few minutes. Now I'm at the end and 😲 I'm floored.

[@kstaxman2]

You bring on the best people to interview. Love your work and dedication in bring science to the people.

[@Rayceemon]

Really enjoying these longer, more in depth interviews, Fraser. Another fascinating topic and discussion.

[@MrDowntemp0]

Seems like the perfect project for those 2 spare hubbles NASA has. Send them up one at a time, then send a crew up to connect them with rigid struts and an interferometer.

[@denysvlasenko1865]

Two telescopes only give you good resolution in one direction. Need more, preferably many more.

[@frasercain]

One is already being used for the Roman Space Telescope. But yeah, if the military has more to donate.

[@SeanBZA]

@@frasercain Just need to get some of the spares that are launched under those SpaceX DOD missions, and replace the firmware on them to get better long term stability, and also to be able to get long exposure times as opposed to the existing ultra short image times they use, plus turn the gyro units around so it points the other way, and add on some star finders, and a sun tracker to close the door when it is going to point too close to the sun.

[@htopherollem649]

​@frasercain aren't the two telescopes already in space? when you reported they'd been given to Nasa it seemed as if they were no longer needed as spy satellites because better upgrades were now in use ? did you mention that they hadn't been launched, and I missed it?

[@douginorlando6260]

@@denysvlasenko1865Hubble resolution in the x direction and 20 times Hubble resolution in the y direction can still be very useful. Many objects are point light sources like a double star. And several images taken with a rotated x,y axis can allow recreating an image with high resolution in both x and y directions.

[@Rayceemon]

Great interview. Good luck to Dr. Gerard in his great interferometer quest. It sounds very promising and very practical to build. Let's get this done..

[@ARWest-bp4yb]

Fascinating, I just hope all us middle-aged guys are still around to see interferometers in space!😄👍👍

[@ChristophersMum]

Mind blown!! What an amazing interview...ok now...let us get it done😃🌠

[@MatthewMaughan-w9r]

This is fantastic again. I really love these discussions. If only I had several billion to fund these types of projects.

[@Jarlaxleify]

YOURE THE BEST, NEVER FORGET THAT. MY CAT STEPPED ON THE CAPS LOCK

[@jasongarcia2140]

You left it on but yea he's cool

[@FirestormX9]

CATS ARE THE BEST TYPERS EVER

[@CarFreeSegnitz]

thE WORst iS WHen YOUr cat and YOu are FIghtinG OVEr thE CAPS-Lock kEY.

[@AndrewBlucher]

TELL YOUR CAT TO STOP SHOUTING

[@CAPSLOCKPUNDIT]

YOUR SIGNAL IS COMING IN LOUD AND CLEAR. WHICH BRINGS UP AN IMPORTANT QUESTION: HOW TO LEVERAGE THE POWER OF CATS TO IMPROVE WIDE APERTURE INTERFEROMETRY?

[@melvyndavis2745]

I just love this concept! So simple, so inexpensive and so scalable.

[@gregoryfrechou]

oh screw 2". give this team 2.5m and two remote collectors. national priority.

[@toddablett4493]

What an amazing interview, and the best part...in summary there are more questions I now have than when it started. Thank you Fraser and team.

[@seditt5146]

I been fascinated with interferometers since I learned about them in Radio telescopes as a child. Thanks for this, I pray I live to see the day.

[@iamjessieray]

This was a great interview, I've also been obsessed with interferometers. I would love to build a small array of radio telescopes in my back yard even!

[@hive_indicator318]

LOWELL!!! Sorry, I'm from near NAU and am happy at remembering that gorgeous place

[@rabindramishra00]

Awesome interview, absolutely loved it! I sometimes skip interviews but so glad I didn't!! 😃

[@EmergentStardust]

That was really fantastic. I hope to one day live through there being a large cluster of interferometer telescopes that can resolve details on other planets.

[@Qrul]

Very informative. I love these interviews!

[@galengloetzel1441]

A very interesting interview! Thanks for all you do to bring this information to the general public!!!!!

[@galactician]

Great interview! Dr. van Belle is totally going to be played by Brian Cranston in the movie.

[@Micetticat]

I stumbled in your channel just now. How could I have missed such an amazing program?

[@CJ_Ludwig501]

Great interview

[@patrickmchargue7122]

Very interesting. Thank you both for explaining this so well.

[@jdbrinton]

Solving one term of the Fermi equation at a time. Love it.

[@PaulShanley]

You are uncannily excellent at this. Period.

[@ReedCBowman]

1:02:38 We do have quite a few pixels of Betelgeuse, though, unless I'm completely misunderstanding something. They've been viewing the irregularity of its disc since at least 2017, from ALMA at least, and those are not small discs on the images.

[@swainscheps]

2:00 “enjoy the conversation with Doctor Jared Van Belle…” /cut to interview/ “Gerard, thanks for being here…”

[@mskellyrlv]

I just read Thomas J. Kelly's (no relation) marvelous book "Moon Lander", and it mentioned the fact that the later missions placed not only seismographs on the Moon, but active seismic sources. The most intriguing to me was reference to mortars the astronauts set up, which, after their departure, launched rocket-propelled explosive charges to wide distances. Apollo, in effect, set up a seismic interferometer on the Moon, and that is how we have mapped its interior. Here's where to start: en.wikipedia.org/wiki/Lunar_Seismic_Profiling_Experiment

[@johnaweiss]

Fraser, i really appreciate your programs. One of the best space programs on the web. You have amazing access to insiders, and love the depth of your reporting. What year will we be able to image the surface of planets around Alpha Centauri?

[@fransahm1956]

This was simply deep info. I loved it !!!

[@bobbyshaftoe]

Best episode ever. imo. Optical interferometry is the future.

[@PhotoArtBrussels]

Fraser, for the interferometer, the conversation about the distance and the signal becoming fuzzy; if the ideal distance is 80meter, you can place a third one, etc, would that increase resolution or cover more angle; or maybe it is a choice of the telescope configuration, maybe even reconfigurable?

[@normvargas2799]

A third telescope would benefit as now you would have 3 pairs of telescopes and 3 fringes instead of 1. You also get a closure phase with 3 scopes which gives data regarding asymmetry of your target. Non-spherical stars and binary systems benefit from 3 scopes versus just 2.

[@jbruso123]

Breakfast = egg sandwich and an engaging Fraser Cain discussion.

[@elephantsarenuts5161]

Excellent interview.

[@Ava31415]

Sounds like an excellent (test/dummy payload?) use of optimus to lay out 100 of them on about a (1km/100m?) grid on starship's first lunar landing? He's answering questions as I type...

[@DamianHallbauer]

This great video make me even more impatient about lunar missions by publicly traded / private startups., and self sustaining colony which is so feasible and so late. , We had one success this year. but Starship, in 2036? 8 refuels on that beast? they are delivering intuitive Machines Nova C on an F9, IM-1 was brought part way and it landed successfully, Im-2 got a huge contract, and others to do that and Optimus isn't part of the picture, nor do Starship CEO really care about the moon. we don't need androids with one hour batteries ,we need to put our boots on the ground of the Moon for a second habitat. . certain people have fans, but not friends to question what they are doing. they SpaceX spacesuits work, a private team paid for that mission themselves and people could go there on falcon 9s. i don't know why this Mars obsession .,. we can actually build a real starship if we were in the vacuum we'd could make so much progress. Love the SpaceX but they have too many unnecessary projects, and real investors on lunar colony startups suffer delays . The moon will give us that "multiplanetary" step, even if its a moon, its immunity and support to catastrophe that happens on earth.

[@alexeifando747]

The idea of measuring the the smallest thing ever - the plank length, using the biggest thing ever - millions of light years of quantum foam, is poetically beautiful - love it 00:29:46

[@Yattayatta]

Amazing interview! I hope they get to fly their small test mission!

[@chris-terrell-liveactive]

Another fascinating interview, thanks Fraser!

[@DaveEtchells]

What a fantastic idea! (2” mirrors on a cheap moon lander.) I’m confused on one thing though: He talked about the light being carried back over an optical fiber to be merged with that from the other mirror. You can funnel all the wavefront detail from the whole 2” mirror down through a single fiber? (Or if it’s a multi-fiber bundle, basically the same question: how do you maintain all the resolution of the wavefront data from the mirror?)

[@jamesphillips2285]

I suspect it is a fiber bundle like an endoscope. My understanding is that the termination is more expensive than adding length.

[@atk05003]

I suppose as long as you have enough fibers in the bundle to provide at least as much resolution as the separation allows, it won't be a problem. Optics aren't really my field and I was also wondering how fiber optics would impact the signal.

[@TheAlchaemist]

You can really use optics to focus the entire aperture into a single fiber, that's pretty much the point.

[@DaveEtchells]

@@TheAlchaemist Amazing that you can retain all the wavefront detail after focusing it down to a he diameter of a fiber 🤯

[@atk05003]

@@TheAlchaemist I thought that bouncing down the fiber distorted the optical signal, making each fiber mostly useful as the equivalent of a single pixel.

[@iantaylor230]

I like it when the US uses grenades for goodness...

[@marcusambler4205]

Thank you Fraser... Loved that

[@slowercuber7767]

19:50 seems like you could isolate each telescope in a lunar surface interferometer from seismic disturbance by the simple expedient of mounting each on a heavy base that is separated from the ground with various inflatable "mattress" layers, each tuned to absorb a different band of frequencies of surface motion. Doing this could reduce the amount of low latency quick dynamic adjustments needed might even eliminate them. A simple direct analogy is a home hologram table, made from a few hundred pounds of concrete and held off the floor by inner tubes. Certainly one would have to be able to shield the telescopes and mounts during lunar day from heating, but that seems a lot simpler and less finicky than having to constantly move the telescope optics around to maintain wavelength scale distances while bouncing around on a jiggly surface.

[@deezmemes7253]

Interesting. Once peripherally in college was aware through a friend working in astronomy lab of their VLBI (very long baseline interferometry) calibration where the participating radio telescopes accessed by my alma mater, and others around the world, were both anchored to cartography points with laser measurements for very precise location registration and their signal timestamps synchronized with atomic clocks to make the signal data of the participating radio telescopes coherent in a way that their superposition was possible to contain the planetary size virtual radio telescope accuracy of measurement.

[@ruperterskin2117]

Appreciate ya. Thanks for sharing.

[@hodgesjaso]

Great interview. Loved it.

[@John-tc9gp]

We should use this to image alpha centauri system

[@lohikarhu734]

A very good for of mine worked on the development of a interferometer radio telescope in the 1960's-1970's...big PCBs with many, many TTL ICs..

[@richardcollings4736]

great informative discussion super stuff thankyou

[@df0rce]

Awesome show!

[@quadmasterXLII]

Jovian L2 interferometer: it's in permanent eclipse, so no worries about solar radiation and no difficulty cooling anything, nothing ever changes temperature or shape. Put a 40 kg RTG and 12 100 watt lasers (only use 1 at a time) on each mirror element, and there's your precision manuvering- photon momentum is plenty (1 m/s per year, or 4 days to do a 1 km manuver). No moving parts!

[@ah244895]

Ditto… great interview, easy to understand but didn’t dumb it down.

[@seyoch]

super interesting interview!

[@youtubeurevil]

Undoubtably a Dutchman from origin with such a name!

[@RogerGarrett]

The two Keck telescopes on Mauna Kea in Hawaii were designed to do exactly that. They were only 85 meters apart. And try as they might, the astronomers were never able to get them to working using the interferometry method described in this video. Keck 1 and 2 are now used separately, no interferometry at all. They were a failure. And this video wants to arrange a whole ring of such telescopes. Good luck with that.

[@rd9831]

Good luck to you in your space interferometer project.

[@richardmarkham8369]

Fascinating. So are the 'simple' pair of telescopes planned for the initial mission on the moon steerable? They have to track the target star together and still maintain nanometer accuracy?

[@josepheridu3322]

Imagine living long enough to see appreciable pictures of close exoplanets 😍

[@coulie27]

This is awesome 😎🙌

[@douginorlando6260]

Space based interferometer array is obviously the ideal cost effective sequel to the JWST. The trade off is requiring more photon gathering time than a telescope with more light gathering surface area, so only specific directions of interest with small angular fields of view can be observed. It may only provide 100 ultra high resolution sensitive images per year but those 100 images would prove or discover many things. If done right, the total weight would be very manageable. In space with no wind, no gravity, and protected from direct sunlight, Ultra light weight spars could hold mirrors 100 meters away from the center and provide a stable/dynamically adjustable frame to position every mirror within a fraction of a wavelength. A 200 meter diameter mirror would provide 33 times higher resolution than the JWST. Even if it took 10 full days to gather enough light, the result is worth it. And with a modern approach using thin mirrors, one Falcon 9 could launch 20 large mirrors the size of starlink satellites. Ideally, the interferometer array structure would be assembled as the manned space station of on the moon. If done right, the cost should be a small fraction of the JWST program cost.

[@denysvlasenko1865]

The spacecraft wouldn't be connected at all. (Long spars would have unpleasant vibration modes, aren't feasible for kilometer+ distances). The spacecraft would fly in formation, keeping the fixed distance. The formation keeping can be achieved by laser interferometry (the force of light pressure from lasers is zero due to destructive interference when distance is exactly right, and increases when spacecraft drift away from this ideal distance by a few nanometers).

[@denysvlasenko1865]

> And with a modern approach using thin mirrors, I'm not sure we have the technology for ultra-thin mirror good enough for optics. But the "normal" several-cm thick mirrors would do. We don't even produce *those* in significant quantities, and build times are something like 4 years for 8m-class mirror.

[@denysvlasenko1865]

> Ideally, the interferometer array structure would be assembled as the manned space station of on the moon. If done right, the cost should be a small fraction of the JWST program cost. Why "manned"? IT's totally okay to just launch telescopes as normal satellites, unmanned. "Manned space station on the moon" for less than $10B? I don't think so...

[@douginorlando6260]

@@denysvlasenko1865 every solution has pros and cons and deserves consideration. I am thinking the spars have the mirrors mounted without actually touching by use of permanent magnets (to minimize vibration) and the spars allow a means to dynamically push the mirrors into precise locations (again using magnetic fields but this time electromagnetic). Both the mirrors and the reference locations on the spars next to the mirrors are all located using interferometry. The mirror corrections are made by small mechanical adjustments to the spar magnets. The small force/ low power electromagnets make corrections not nulled out by machnaical adjustments plus actively damping out/eliminating any vibrations in the mirrors. The mirrors have significant weight so any vibrations they have would be very low frequency. The mirrors are actually assemblies with a Numerous peizeolectric adjustable spacers to a backplate to allow adjusting/eliminating distortions in the mirror geometry. This magnet separation may be overkill. Multiple mirrors at identical off axis distance will all be ground and polished to the same shape, making production easier/cheaper. The telescope can forgo visible wavelengths and start at near infrared depending on cost to grind/polish mirrors to 8th wavelength at 500 nm vs at 1000 nm. Even 2 micron wavelength would work well for distant objects due to Hubble redshift. Ideally, the telescope needs a spectrum analyzer to measure the spectrum of light refracted through an orbiting planet’s atmosphere. The high resolution will allow collecting this refracted sliver of light around a planet without collecting the star’s direct light. The absorption lines in the refracted light’s spectrum will reveal which molecules are in the planet’s atmosphere (including evidence of life friendly environment like water vapor plus evidence of life itself (oxygen, methane, etc). This will allow radio telescope arrays to concentrate their effort on detecting use of the electromagnetic transmissions on those prime candidate planets for intelligent life.

[@douginorlando6260]

@@denysvlasenko1865 I suspect low cost high quality mirror systems can be mass produced by several tricks 1… economy of scale and increasing the automation/real time gpfeedback during the grinding/polishing process 2… relaxing tolerances by forgoing using the telescope for shorter wavelengths like Visible vs near infrared 3… zero gravity means no mirror sag plus much reduced strength requirements for support structure. 4…. Include a back plate with many piezoelectric spacers to allow more localized dynamic corrections. Each piezeoelectric spacer can be dynamically adjusted by pushing between the back of the optic grade mirror and the non optic grade generic backplate.

[@Akio-fy7ep]

Formation flying is a lot easier if the birds are all connected together with fibers, and are charged up to a high static charge to repel one another and keep the fibers in tension. Probably you need a lightweight sunscreen as big as the whole array to keep ions in the solar wind from masking the fields. The sunscreen would also need to participate in the formation, and would act as a solar sail, so might best be a bit inboard of Earth's Lagrange point 2. (Sadly, Earth's shadow would not help there, as solar wind is not strictly radial.) Making the sunshade conical would minimize thrust, and be structurally more stable.

[@frasercain]

I like that idea.

[@denysvlasenko1865]

Fibers would vibrate. Formation flying is easier with nothing. "Best part is no part".

[@zachreyhelmberger894]

Great stuff!!

[@edwardbarton1680]

Construction in space (particularly on the moon) has another benefit for telescopes. Get a mold spinning, and a liquid in it (eg molten glass) will create a parabolic surface.

[@christiankrueger8048]

Thank you!

[@rudypieplenbosch6752]

Artemis missions...that's all i needed to hear.

[@plinble]

Hopefully version 2 of the concept is modular, and can plug in more as the need arises. Not exactly a space race, but knowing there's something good going on the moon will be making the ground telescope people work harder.

[@curtisdeer3482]

This is how the Chara Array by Georgia State University works in the basic concept. I helped with it in the early stages as a student there.

[@richardreumerman5449]

Mine blowing indeed, and all very well put. I want to build my own interferometer now! 😅

[@normvargas2799]

You can. Just take a telescope and mask the aperture with small open holes on opposite edges of the lens or mirror. Look at a bright star. The light interferes and under high magnification, you can see the dark lines of the interference in the airy disk.

[@richardreumerman5449]

@@normvargas2799 that's really cool, I need to try this thank you

[@kevinICdesigner1]

awesome

[@Yezpahr]

Took me 10 seconds of looking at the thumbnail til my brain stopped reading "Optical Illusion" and started seeing "Optical Resolution"... I blame the algorithm. It threw a lot of such videos my way in the recent past.

[@glasseyemarduke3746]

Looking forward to hearing about the grenades the Apolo astronauts used on the moon.

[@theunknownunknowns256]

Question. The Monday question thing. Everyone including here, talks about the "simulations" or "models" of the early universe, and then show a pretty graphic of the early universe. Every now and then I'd like to see what the scientists see from these models god dang it! Hank Hill reference, but pointing it out probably loses something.

[@JamesCairney]

This was really good

[@fernandoschuindt1665]

Also, mind that one of the advantages of space telescopes is that you eliminate planet rotation, so you don't have to wait for a given object to rise, and you can do 12h+ sessions, since you also won't have a day-night cycle.

[@BestBFam]

Thank you.

[@AndyKong51]

I don't get the idea of why we cannot combine many small optical telescopes together through ethernet. For the fit file, doesn't it have the timestamp? If the NTP time server is not accurate enough, the telescope can get the GPS clock instead. Thx @13:40 does the "coherent" means time? Nanometer tolerance? After photo stacking, the noise can be reduced a lot, right? Thx

[@unitrader403]

i think for optical light you need somewhere in the region of femtosecond (10e-15) accurate timestamping (basically the wavelength divided by c, maybe even half that), GPS timestamps are accurate to about 130 nanoseconds on average (10e-9)... So there has to be an improvement of 8 orders of magnitude minimum to be useable. (basically you have to get the time of every wave of the light arriving, so you can match it to the very same Wave on the other Telesecope) Also GPS timestamp wasnt good enough for the EHT either, they have afaik used an own atomic clock at each location...

[@CamAustralia001]

Fraser, I recall doing the calculations of resolving power. Put a range of hubble space telescopes around Earth orbit and connected up as an interferometer, and one could resolve street maps on some of the planets in nearbye star systems. Technically not achievable, various issues, including stability of orbits and refuelling. Also sensitivity is an issue here separate to resolution power. But fun calculations. Oh yeah and the analogue vs digital issue. (oops).

[@bobbyshaftoe]

It seems like timing is the single most critical element for planetary-surface levels of resolution. Lets go big: 1 meter at 100LY. To get this done, the collection optics would need to be a couple AU apart. Rather than relying upon quantum networks (which will be great once we actually have them) couldn't we simply capture images and then beam the data to a centrally located interferometry center in an out of band manner; to ensure phase alignment we would worry more about the time dilatation of the out of band transit operation rather than the actual collection event. This makes it a lot easier, it seems.

[@joebushnell143]

Awesome 👌

[@Mysteries-revealed]

Bars to keep separate, chains to ensure shortest distance bar can afford, with telescopes in between, pulling together, in zero gravity, an interferometer as big as you care to have, orbiting any planet or moon

[@Gridl6]

That was great. I think that Boston Dynamics could build some very agile telebots with telescopes instead of heads that could walk in a straight line unreeling fiber optics cable. From here my imagination goes nuts.

[@0rderofTheWhiteLotus]

I cannot WAIT till you do the deep dive on friggin MOON GRENADES.

[@rJaune]

Would a Moon Interferometer be affected by astronauts working on the moon? Great interview! Thanks so many much!

[@richiebricker]

I think you could make some amazing 3D Stereoscopic pics and Stereo Time lapse movies! Yeah, get er done already

[@johnmaas9730]

I am of the opinion that the limitation in resolution in all large telescopes is a function of the perfection of the device more than the aperture. With that in mind I did a calculation that I think is correct. If the James Webb Telescope were mechanically perfect, going by the aperture, the resolution would be (about) .02 arc-seconds. The claimed resolution is .1 arc-seconds. For reasons I will get into, I suspect that .1 is a brag and it doesn't due that well. The purpose here is not to be critical of the Webb telescope. I am sure it is well made. Rather the opinion here is that if we want higher resolution, it is more likely to be accomplished by a more perfect device than a bigger telescope. And that increased perfection can be accomplished. The consideration is that when the image of a mirror is magnified, the magnification also magnifies whatever errors are in the image. Looking at the Webb telescope and knowing how optics work, it is apparent from the appearance of the design that the secondary mirror magnifies the image a lot, which is why I doubt it can even get to .1 arc-seconds when the theoretical max based on aperture is around.02. So... Want higher resolution? Forget about bigger overall. Think longer focal length so as to get a large enough image without additional magnification. The goal here is maximum resolution, not maximum light. Leave the inner third or more of the primary mirror vacant, and then either place the light sensing device in the focal point of the primary mirror, or have a secondary mirror that magnifies the image a lot less. Either would work, and best would be to have the sensor at the focal point of the primary mirror, thus avoiding also the errors induced by the secondary mirror.

[@denysvlasenko1865]

> The consideration is that when the image of a mirror is magnified, the magnification also magnifies whatever errors are in the image. Your assumption that today's telescopes are not built to the necessary surface precision is completely wrong. They are built that well. The newest polishing techniques (computer-aided water polishing and such) can even manufacture surfaces with sub-10nm smoothness, which is good enough for far-ultraviolet optics (used in semiconductor lithography).

[@rogerphelps9939]

0.1 arc seconds is nothing special and well within the reach of Webb. Resolution is a function of wavelength and aperture. The shorter the wavelength and the bigger the aperture the finer the resolution. If you chop areas out of a primary mirror you reduce resolution, increase diffraction rings and reduce sensitivity which are all not particularly good ideas.The resolution achieved by ground based telescopes depends on atmospheric turbulence or seeing. Resolution can be maximised by placing telescopes in dry air a the tops of mountains. Adaptive mirrors can compensate for residual atmospheric distortion but the technique is limited. Interferometers achieve high resolution at the expense of sensitivity and in order to synthesise a two dimensional image a way must be found to rotate the line joining the mirrors. This can be achieved using the rotation of the Earth or orbital motion but takes time. I suggest ha you learn about optics.

[@2ebarman]

Wait, are you saying that diffraction-limited resolution is not a thing? I thought it was a physical law, and a longer focal length without increasing the aperture can not result in better resolution due to fundamental physics. I'm very confused.

[@johnmaas9730]

@@rogerphelps9939 Resolution is not determined by wavelength and aperture. What wavelength and aperture determine is the maximum resolution that can be had in a a device that is perfect. As no real device is perfect, that resolution is never really reached. In the smaller aperture devices one can come really close. In the larger aperture devices the theoretical maximum resolution is commonly not reachable because the error term part of it induced by the failure of the device to be perfect gets bigger relative to the possible maximum. As resolution goes up, any given imperfection becomes more important. Also, if resolution is said to be a function of wavelength, then resolution becomes a variable that depends on wavelength and any statement of the resolution achieved would have to include the wavelength used when measuring the actual resolution. So, it can achieve 0.1 arc second. At what wavelength? I haven't read any optical theory in a long time, so I am speculating here to some extent. But what I recall is that the resolution achieved when the light rays come into focus is actually produced by at how great an angle there is between the rays as they converge on the imaged formed. Thus for the same focal length, a larger lens gives a sharper image because the light on the edge of the larger lens is coming in at a steeper angle on the image formed. That is also why the interferometer stuff works. With regard only to resolution, you don't actually need the light from the center. Thus the further apart the optical devices are placed, the higher the possible resolution.

[@johnmaas9730]

@@denysvlasenko1865 When they built the Hubble Space Telescope, the criteria used to determine how much glass to grind away on the mirror was measured as a distance from a point. That is the sub-10nm smoothness that you refer to. It is a measure of distance. The problem that developed was that the focal length of the lens actually depends on the slope of the glass, and that is not perfectly measured by the distance from some point. They thought they had near perfection going by the the measured distance. It had zonal defects because the actual focal length depends on the slope of the glass, not from a distance measured. It had serious zonal defects. As they screwed up last time, I would imagine this time around they checked the actual focal length. It is not that I think this stuff is badly built. It is just that the design of the thing pushes the limits of what can be accomplished. That allows them to brag about how super impressive the thing is, but doesn't make it more likely to work.

[@kimvette1]

I've been hoping we would start doing these inferometry telescopes in space and start deploying them across the solar system for pushing our view out even farther.

[@donerskine7935]

A lunar array is just the sort of project that could be assembled on the moon by robots or automation.

[@seditt5146]

As far as formation flyers go, if two scopes started in contact with mirrors at a known distance and a known force was applied dislodging them would this not only give increasing resolution over time but also allow for rather good nanometer location of the mirrors or would noise from gravitational interference and gyroscopic forces kick in to throw them off beyond use? It feels like they should drift apart at a known speed and time since split should all one needs to know. Hell I could see such a system getting on opposite sides of the solar system with little divergence from baseline.

[@kellyhofer]

I am surprised that terahertz computing wasn’t mentioned as being the missing link to make optical interference imaging possible.

[@plinble]

Need to read up where the technology is at to have well separated interferometer telescopes, like for radio waves. Is it fundamentals of physics or better components needed? As soon as you realise a photon your interferometer doesn't work right? Quantum physics etc? He's talking about 100m fibre optic cable, not so bad, people would try his 2 inch concept on the ground, but in a building. Very educational.

[@ZapperGazer]

Sending a Magellan-sized telescope into space should only take a fresh set of mirrors, and a squadron of Starships. Multiple observatories in orbit across the solar system ought to be very useful.