We Really Need a Far-Infrared Space Interferometer. Here's Why
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- Опубліковано 26 чер 2024
- JWST has shown us what the modern infrared telescope is capable of. But it's not far-infrared. There are no space telescopes operating in that spectrum at the moment. But why? And what would we be able to see if we had one? Let's find out with Dr David Leisawitz, Chief at NASA Science Proposal Support Office.
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00:00:00 Intro
00:02:08 What is far infrared
00:10:24 How is far infrared useful for Astronomy
00:24:56 Space-based interferometers
00:44:43 What will we be able to see
00:52:55 What's next
01:00:56 Current obsessions
01:04:59 Final thoughts
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You are free to use my work for any purpose you like, just mention me as the source and link back to this video. - Наука та технологія
We are so amazingly lucky to have a journalist with a scientific and critical thinking mind to ask practical yet precise questions to brilliant minds like Dr David Leisawitz bring us bleeding edge astronomy and cosmology in an understandable conversation. I’m just a school bus driver, but I can watch and rewatch the parts that I don’t understand (thanks to the miracle of UA-cam) just like I did reading Scientific American back in the 60’s as a grade schooler. I’m grateful to Dr Leisawitz for his patience and to you Fraser Cain for your outstanding brilliance.
I support the interferometer idea in this wavelength range, and I also agree that it makes finding spectral fingerprints a lot less dodgy if we are not missing huge frequency ranges.
When fraser said his audience is advanced it made me really appreciate why I watch this channel. Made me smile. Fraser is right, of course, I already know what an interferometer is and dont need to hear about pebbles or balloons or whatever for the 1,000th time.
I also really appreciated that he encouraged Dr Leisawitz to skip over that explanation. It also gave me. Chuckle how he ran with it and got very technical. I had a hard time keeping up with the terms but I think I followed along well and loved the challenge 😅
We've got to start thinking about how to service and refuel these kinds of satellites autonomously.
A space based interferometer, for example, would really benefit from regular autonomous propellant deliveries.
It would take a lot of standards coming together, what kind of propellant, in what format, how to attach it to the satellite, etc.
If it's done right, the same tech could be reused by lots of different projects.
This is a part of space infrastructure I've been thinking of. Along with autonomous garbage collectors (to de-orbit space junk).
One of the benefits of a working Starship is that you can send service craft out to specific objects/satellites/missions, and then recover them when they're done, AND STILL have massive amounts of cargo space/mass budget left over, compared to current heavy lift vehicles. It really will be a complete game-changer... IF it can get off the ground! =D
A big problem is they dont tend to be near earth. So getting to them would be quiet tricky.
There are, however, various commercial projects looking at refuling normal satalites.
@@deth3021 I wasn't thinking of refueling existing satellites - I'd expect for most of them it would be near impossible, and the risk of damaging the satellite would be high.
Rather, it's an idea for designing future satellites, with the more agencies agreeing on a standard, the better.
I was thinking of a modular format that's basically a tug for a fuel tank that would attach to the satellite.
The satellite would probably need to be launched with no fuel, and the fuel tank would be attached in orbit.
The advantage of using this format would be lower launch costs for the satellite, reusability, longer lifespan for the satellite, and lower potential orbits.
As well as opening up the possibility for lots of interferometry.
Also, maybe to explore more asteroids it would make sense to have a sample returning vehicle in Earth orbit, and use a different kind of reusable probe to gather the samples.
Once a system like this is in place, all kinds of applications grow out of it.
@jamesnicholl4730 like i said, that is more or less what is already being investigated for normal satalites.
It isn't likely to be done for these types of space telescopes due to where they are positioned. Especially the infra red ones, as they are positioned further away to be outside the earth's heat plumb.
Great interview. He answered some questions that I didn't know to ask. Like the difference in resolving potential between a telescope and an interferometer, or the quantum limits of heterodyne based observation.
This is genuinely one of my favorite interviews this channel has ever done, Fraser. I've come back to watch it again a few different times now, and it's just so fascinating. I absorb an extra fact that didn't sink in each time, and I can safely say I'm beyond on board the far infrared bandwagon lol!!
Great interview, David has calm way to explain things.
Boring actually. I slept through most of it.
Great interview Dave! You were very clear and articulate.
I really enjoyed this interview, Fraser. Thank you, and I'm looking forward to seeing more of them soon!
would have been nice to hear Dr Leisawitz give a brief description of an Interferometer.
Great interview. Thanks Frazier and Dr Leisawitz
Well, you spelled Leisawitz correctly.
See W Shakespeare: What's in a name?: And Leisawitz is easier to spell. @@deepdrag8131
let' 's hope he gets what he needs to make this telescope a reality! great interview, very informative!!
Fantastic guest/interview.
Fascinating! Good interview, Fraser.
Just imagine what’s right in front of our eyes but we just can’t see it, imagine. Great interview.
Yeah, that's the problem, to much imagination not enough science
Great interview for infrared telescope, I love infrared telescopes
Multiple infrared wavelength space telescope (MUIWAST) 25 meter telescope From
Near IR to Far IR telescope an general infrared telescope
Amazing interview as always. Great guest.
Another great interview Fraser. Thanks.
as always great interview, with great guest and question
Seems like a structural interferometer could be assembled at the ISS, and tested iteratively. If it gets to the point of usability and operational resilience, then it could even be launched from the ISS.
Well, it certainly would not work well anywhere close to the station. Assembling a telescope larger than any rockets can support would allow for some interesting telescopes though 😮
Fascinating discussion, as usual!! One thing I don't understand, however, is how any of the first space interferometers could significantly outperform ground based interferometers that are getting better all the time. It would be very difficult, I assume to produce a physically connected interferometer that had an "äperture"" width as great as 50 to 100 meters. But ground-base interferometers are already operating with greater separations than that. The ground-based variety do have some big limitations of their own, of course. The most troubling of these is probably that aside from the small window at 2.2 microns earth's atmosphere blocks out the rest of the infrared spectrum. Still a lot more can and will still be done with terrestrial interferometers. On the other hand, if space interferometers are ever to get larger they must obviously start out with smaller prototypes.
I'm a relatively new viewer of this channel, so can't judge comprehensively, but this has been an especially compelling interview. Thank you both.
Huh, I'd never heard of that "nulling" interferometry way of blocking starlight. Really interesting.
A very interesting interview about what should be possible with a relatively short baseline longwave infrared interferometer. However, it was disappointing that David Leisawitz seems focused on the traditional model of doing projects in an outdated NASA large budget, long timescale methodology. I would be very interested to hear an interview with Charles Lawrence (chief scientist, astronomy & physics, NASA JPL) on what might be possible when taking advantage of the much lower cost & high weight launch capability of Starship (see: Physics Today, vol 76 issue 2, Feb 2023)!
Chat with DR Leisawitz was wicked, loved it when you pulled him up and said your audience knows the basics of an interferometer.
His whole approach changed and became more relaxed.
A far infrared interferometer would be an ideal instrument for spotting large kuiper belt and oort cloud objects. I'd bet on there being at least a couple hundred "minor planets" out there bigger than Pluto. I'd be more interested in the trajectories, number, composition, and size of "foreign" objects wandering through our solar system and not bound to it, than in studies of the early universe or searches for life.
Wow - genius!! Thanks
I'm less excited about proto planetary disks than I am about the potential to begin to map the structure of the Cosmic Web - and maybe even begin to understand how much mass within this flow of ions and electrons has previously been unaccounted for...
Excellent guest.
I would push an adaptation of interferometer approach for widely separated space telescope mirrors that work more like a telescope and less like an interferometer. 4 mirrors mounted on the endpoints of an X cross frame could allow an effective objective aperture 30 meters in diameter. It easily fits inside a starship. The 4 extension bars each 15 meters long unfold from the center of the X. The secondary mirror is mounted on a frame inside the 4 folded arms that do not unfold. Like Doctor David said, longer wavelengths make alignment much easier.
The net result is a space telescope with 5 times the resolution of the Webb for infrared wavelengths for a few hundred million dollars. The only downside is low light gathering rates will require 10 times longer exposures/ photon collects. If the price is jacked up to a billion, then the Webb sensors could be used to reduce risk & schedule & cost, temperatures could be controlled down to 10+ micron usefulness, plus the mirrors could be farther apart to increase resolution.
For the post baby boomers, "Gang Busters" was a radio police drama from 1937-57, which always opened with sirens, screams, gunfire, and loud dramatic music, so to "come on like Gang Busters" has an obvious meaning, still used today. Otherwise we would have to say something like "come on like Monday Night Football."
smart guy , great interview
Glad you enjoyed it
This really does need to be bumped up levels in priority...
When the Starship comes online, the Giant Space Telescope Launch Foundation totally expects to have a full flower set of 8.4-meter mirrors ready for the Giant Magellan Space Telescope Observatory ready.
Imagine an optical telescope that operated at 4000 degrees. I would be hard to see stuff as it glows.
Thank you Fraser, i would like to give this interview a great thumbs up. Having watched many previous episodes I still found this Professors explanation of far infrared so incredibly informative and explanatorial. Great science communication at work.
cheers
£fourier transform spectrometer
talking about numerical aperture, diamond is the best for microscopes.
I look at the small na1.9 is good enough
The numerical aperture (NA) of a lens determines its ability to focus light and its resolving capability. Having a large NA is a very desirable quality for applications requiring small light-matter interaction volumes or large angular collections. Traditionally, a large NA lens based on light refraction requires precision bulk optics that ends up being expensive and is thus also a specialty item. In contrast, metasurfaces allow the lens designer to circumvent those issues producing high-NA lenses in an ultraflat fashion. However, so far, these have been limited to numerical apertures on the same order of magnitude as traditional optical components, with experimentally reported NA values of 0.99) and subwavelength thickness (∼λ/3), operating with unpolarized light at 715 nm. To demonstrate its imaging capability, the designed lens is applied in a confocal configuration to map color centers in subdiffractive diamond nanocrystals. This work, based on diffractive elements that can efficiently bend light at angles as large as 82°, represents a step beyond traditional optical elements and existing flat optics, circumventing the efficiency drop associated with the standard, phase mapping approach.
DNA abs spectrum at 595 from memory not sure
I wish the videos with interviews said they have them so that people who aren't interested in seeing any interviews don't waste their time clicking on it.
Try checking the run time on the video: the ones with interviews typically go well over 40 minutes to an hour+. =)
Look at the Modulation Transfer Function at intermediate frequencies for this kind of system unless you have many individual telescopes, the MTF does to zero or vary small.
One thing ive noticed in discussions of these space based interferometers and G wave detectors, is no mention of how they are kept lined up perfectly and maintain an exact distance with so many moving objects, you need them to stay aligned within nanometers to work
But in orbit, thats impossible, place them vertically and one will drift forward because of the difference in orbital period, place them to the side, amd theyd be on different orbital planes and drift closer and then farther, place it ahead on the same orbit, the earths gravity isnt even constant due to differences in density and moving tides and the moons gravity and the gravity of other planets
There is just too many variables to keep them aligned perfectly at a fixed distance without being connected by a rigid body or near constant thrust corrections
In the case of SPICE, the apertures are held together by a rigid body. Also at far-infrared wavelengths, the relative position between apertures needs to be maintained to micrometer precision not nanometer.
There must be a way to estimate how many big discoveries would be found in the 25 to 450 micron band … based on how many were found in every new band (mid infrared, gamma, x ray, radio/microwave band). Compare the list of important discoveries from each of these bands and you get an estimate of the quantity and importance of new discoveries the 25 to 450 micron band would reveal.
I would love for a guest to answer the what are you obsessed with right now? Question to be like quesadillas oh man, I just can't get enough of quesadillas.
Hah I'd roll with it if they did.
It's simplistic: put a far IR telescope at each L4 & L5. Excellent interview. So, how big would the mirror be if the telescope were folded-up like the JWST and stuffed into Starship?
I kinda feel called out for my question about the LCRT during the Q&A. But hey, FOR SCIENCE!
22:12 Spectrometry, water lines
40: a memory frame buffer would work !
i would call this episode- 'a canticle for leisawitz by the frasercan space monk'
😜
4:20 Cost again... dang.. 4:35 sweet graphic❤
Starship really is gonna change astronomy.
And bankrupt the earth
Why does it seem that we invest billions in developing Hubble, jwst, etc, and yet we don’t create a fleet of these? Half the cost of jwst is figuring out how to do what it does & developing new tech. Now that we have that figured out, shouldn’t we be able to build at least 1 or 2 more far cheaper, bcuz we don’t have to figure out how to fold mirrors, etc?
"We need a far infrared space-based interferometer"
Oh, you mean only the holiest of holy grails....yeah, I agree 😘
29:20 ... aye...... so, like noise cancelling headphones but for light and for telescope eyes?
Do the few windows of far infrared that make it through the atmosphere have any biochemical effects?
35:14 I thought for sure that Dr David Leisawitz was going to say that the interferometer was going to maintain formation without propellant, that is, using radiation pressure just like the Kepler-K2 mission did. Since he didn't, could a constellation of telescopes in heliocentric orbit maintain formation just using radiation pressure?
Hopefully all this money donated to these projects brings a better life for the average person.
Would they be able to put something like the structurally connected inferferometer on the two ends of the Truss Structure of the ISS?
22:00 wow, this Doc knows his stuff, 😅
He's been thinking about this idea for 25 years.
Wasnt today suppos3d to be the live show? Oh well... this works as well
Could this be combined with statites? Could we build statite far-infrared interferometers?
I would like to thank you for this interview. I have to say if i was a multi Billionaire i would donate to building such a telescope. Couldn't think of a better one. Thankyou.
Ok, that might be a silly question, but if I understood this correctly, we are kind of doing optical (and whatever the wavelenght of hearing is called - para-radio?;) interferometry with our meat computers...By producing a unified FOV which "looks" as big as the each of them can cover sepatately.... And we are doing this interferometry using brains... Which are much more noisier and slower (computationally) substrate to do iterferometry due to alll the noise with transitions/conversions (electricalelectrical, I mean) - anyway... My question is - has anyone done the calculation/estimation - what is the maximum size of a creature based on our type of meat-computing, with stereo vision possible?
Just wondering.
What are the challenges faced for storing cryogenic fuels in space as a sort of gas station in the sky?
Would a Far Infrared Telescope allow us to observe planets that are part of a Brown Dwarf system, even if planets in that system are hidden within the star's corona?
Because Brown Dwarf stars are the most abundant, it seems likely (statistically) that this hidden region would contain the highest likelihood for habitual planets - i.e. planets in the "Goldilocks Zone" very near a cool star with a water abundant halo??
Currently, with our existing technology this region is simply impossible to observe. However, I believe that this is the type of region where we have the highest probability of finding not just habitual planets, but also planets that could evolve life...
But the problem isn't just overcoming diffraction. You need to collect some photons too. And with a planet you have to remember that it goes and hides behind the star. A moving target. I thought Slava Turyshev explained about that. Maybe good to ask him about it. He must have thought about what makes sense.
10:00 - why would the instrument have to be so much colder than the optics? - i understand the whole "infra red glow-fog" problem, but why go to 1/100th of the temperature of the optics for the sensors?
Because if your mirror has heat, you can't see anything.
A sensor that detects itself isn't terribly useful, as you already understand. But also, colder sensors are typically more sensitive within their desired ranges, regardless of what those ranges are. Finally, being able to know for certain that any detections came in via your optics means that any & all stray photons FROM those optics can potentially be corrected for in a way that those from the sensor suite itself cannot be (at least, not as easily).
@@frasercain poorly worded on my part - why should the sensor need to go to 1/100th of the temperature of the optics?
If the mirrors or lens have a emissions of thermal radiation it does randomly(in all directions, and at certain distance from the sensor ) , so only a small number of photons(like 1%,or even less, depending on the geometry of the optical systems and actuall size of sensor relative with the optical system ) reach the sensor and are detected , if the sensor itself do the same thing it would detecting those photons almost certainly, so you can afford from your mirror and lenses to emits 100 times or more photons than your sensors.
Sounds like a "milli" dollar idea. ;) jk!
Great interview! One of my new favourites.
You know what would be nuts? a space telescope package that fits the racks of Starlink satellite dispensers. Enough space telescopes to monitor the whole sky and give every PhD astronomer regular access in a single launch.
How much is being pursued on the end of small-and-cheap designs to leverage reusable launch capabilities? Is this being left to universities with the idea that Starship might be within their budget?
Small telescopes are typically only useful when in relay, in which case only a small team can use the array at a time anyways
Just equip the far-infrared telescope with MORE reaction wheels...plus more spare reaction wheels...
Reaction wheels, all the way down! =D
@@R.Instro =D
What would happen, if Starship gathered in an old far ir spaceship, swapped out its helium tanks for a modern cryocooler and put it back into orbit?
There was a plan to try to save spitzer with something like starship
I still don't understand why NASA decided to cut the funding for SOFIA. This was the only telescope in its wavelength.
It represented an expenditure of funding that was ever increasing, for diminishing returns. It wasn't a GREAT amount, but it was $millions that could instead go to projects like JWST, New Horizons (just extended, btw!), or for something like this interferometry mission, which would be as big a jump up from SOFIA as JWST is from Kitt Peak. =)
SOFIA overlapped with Webb, so they cancelled it. It couldn't do far infrared like Herchel or Spitzer.
@@frasercain Sofia could do up to 655µm and Herschel up to 672µm. It was in some regards basically the same and in others the closest we had. Also the instruments could be changed if needed.
If it took ~30 years to build the JWST telescope, how long will it take to build this, the same? About ~ 30 years? I am not critical, just asking,
And did I hear correct, one thousands kelvin above absolute zero?
Is that even possible? Else, nice and interesting interview
The JWST didn't need so much time just for technically reason only. I wouldn't think it would took the same amount of time. They also have a learning curve here and don't need to repeat the same errors the made initially. I mean, in the end of the day the government wouldn't allow such an expensive project a second time anyway.
@@nanohatakamachi1066 - yes, you could be right, that much is probably learned and problems and delays be avoided, if it is possible to build something like this at all
He said there are already telescopes using those mechanical coolers
1,000 Kelvin is about 1,340°F. 4 Kelvin is about -452.5°F.
@@douglaswilkinson5700 - I meant one thousands of one kelvin
100% voids any warranty of all kinds
Boss statement on youtube: I have a fairly advanced audience so you do not need to explain what an interferometer is.
why must it be in space we should first build a moon sies interferometer. much easier to get the signnals to the computing center.
Can someone explain why the 9 planets have 98% of the angular momentum when the sun has 99 % of the mass ? why do they all have different densities and spin rates ?
It is thought stars have a high angular momentum when they are forming, but they lose most of it due to mass loss via their magnetic fields, bipolar jets and stellar winds. Jupiter has about 60% of the angular momentum. Density depends on how massive the planet becomes as well as what it is made of (eg. rocky planets are on average denser than the gaseous and icy gas giants, with the gas giants being denser near their centre), and spin rates are affected by collisions and gravitational interactions which aren't fully known. Venus and Uranus having the weirdest spins most likely due to collisions with large planetoids.
@@tonywells6990 thanks mate
Imagine just spending 20 years and $10 billion worth of engineering on the worlds most advanced infrared telescope only to have a NASA researcher proclaim that it’s not enough and we need another flagship IR telescope
There will be no limits even when we reach Andromeda with our drone,[$?]
"What is dark matter" - ...particle's.? NO particles cannot PULL. What about ropes, strings, or our theories are just wrong!.. -
Interferometer interferometer interferometer. This conversation would have been much more enjoyable if the host allowed the guest to give his explanation of what an interferometer is.
What's the rush? Just let the guest explain what he's talking about.
What's more, one of the host's questions demonstrated that he doesn't understand exactly what an interferometer is. 😐
Dr leisawitz looks like teller.
Far infrared
On the darkside of the moon. But then cant be used 1/2 the time, but can be serviced and updated.
Great interview. I feel we need a martian pr person. So no scientist on mars lol
Please stop interrupting your guests. Let them finish, and then ask your question.
Its a conversation over the Internet, there is a time delay. I would guess that most interruptions are caused by the time delay due to having the conversation via an Internet connection.
@@JamesCairneymost video call sites or apps are notorious for being finicky with connections
Plus, Fraser is rocking Starlink, so that connection can't be perfect. However, giving guests more time to elaborate, sometimes, would be a good idea as well.
It felt like he was on a race to end the interview towards the end.
Really weird.
Some guests know they don't have the Bandwidth, ...don't, hate, appreciate ❤😅