12 ms·
A solar gravitational lens will be humanity's most powerful telescope (2022)
- koolala 2y agoThis is almost the plot of Three Body Problem. Could we use a Solar Gravitational Lens in reverse and project signals out of the lens in reverse?
- sbierwagen 2y agoProtector by Larry Niven (1973) also features a gravity-powered telescope.
- Cthulhu_ 2y agoI think so, as long as you know how far away your target is (the focal point) to position the sender, and you need a way to send the signals at the right angles "skimming" the sun at the right distance. (note: armchair amateur, this is just conjecture / thought experiments)
- throw901921 2y agoBut why? Sending signal this way does not amplify the signal. Just point lasers directly at that point.
- asdfman123 2y agoCould we do a less extreme version of this with a planet in the solar system? Or would a probe have to be too far away from it?
- worldsayshi 2y agoCool worlds YouTube channel has a great video about Earth sized telescopes: https://youtu.be/jgOTZe07eHA?si=0veG99yEbLQTKs4I https://youtu.be/jgOTZe07eHA?si=0veG99yEbLQTKs4I
- yodon 2y agoA planet would be a weaker lens so you'd have to be even farther away, and you'd have less collecting area as well.
- mbrubeck 2y agoIf you use Earth, you can use atmospheric lensing (rather than gravitational) to get a focal point inside the Earth–Moon system: https://www.scientificamerican.com/article/earth-could-be-a-lens-for-a-revolutionary-space-telescope/ https://www.scientificamerican.com/article/earth-could-be-a-...
- deleted 2y ago[deleted]
- freeqaz 2y agoIs there anything stopping you from putting 2+ satellites out "closer" but in the path of the lensed light, capturing the light simultaneously, and then resolving the image via async computation later? I think this is called interferometry and I know it's hard because you need _very_ precise timing, but I'm curious if that would be possible or not. (Maybe you can get the timing in sync with atomic clocks, or by sending a laser to both from a central point that lets them keep time with some very tight tolerance?) Weird idea but I wonder if there are ways to take this from "crazy tech" to "hard tech".
- colechristensen 2y agoThe precision you need for interferometry depends on the wavelength, and being able to do this over astronomical distances at visible wavelengths would indeed be a challenge. I think the scale is timing more accurate than 0.1 nanoseconds and distance accuracy on the order of 100 nanometers. Near those orders of magnitude at least and over astronomical distances that might be measured in AU. Then again the precision of the gravitational wave instruments measure distance on the order of the width of a proton, so who knows. Terrestrial infrared and optical interferometry telescopes are on the bleeding edge right now.
- vlovich123 2y ago"Boring" cesium atomic clocks can do 50 ps per day with the best cutting edge optical clocks coming in at ~739 fs per day. Optical clocks would only need to resynchronize once every ~ 135 days while cesium clocks would need to do it every 2 days to get 0.1ns of accuracy. I think the bigger challenge may be how you would transport the clocks after synchronization to maintain it across astronomical distances since they're very sensitive to any kind of acceleration. Since you have to regularly re-synchronize them in space anyway, that feels like the engineering problem you'd have to solve - how do you synchronize two atomic; the current record is synchronizing to within 0.32fs at a distance of 300km [1]. [1] https://spectrum.ieee.org/atomic-clock-femtosecond-accuracy https://spectrum.ieee.org/atomic-clock-femtosecond-accuracy
- chgs 2y ago
- deleted 2y ago[deleted]
- mmaunder 2y agoSpoiler: the focal point is 3.5x the distance to Voyager 1.
- trhway 2y agoif to use existing nuclear reactor tech and already existing, as tested by NASA (and drives Starlink satellites), ionic drive - about 3500 ISP - that focal point would take about 10 years to reach. I hope that SpaceX flights to Mars will, after the probably first chemical ones, be done using ionic drive with solar as it is just faster, thus getting tech developed and with adding nuclear for beyond Mars - so in 10-20 years we'll have the stuff flying. (note that "small" reactors - 100MW - we have for submarines, and with MS, ORCL, GOOG, AMZN getting into nuclear we'll have such small reactors productized into normal commercial use which will simplify space use too as commercial use require higher reliability/etc. compare to military)
- kibwen 2y ago> that focal point would take about 10 years to reach Is this taking into account the time needed to slow down?
- trhway 2y agoIt is the napkin scale, not precise mission calculation. Doing 2 stages you can get faster, doing higher voltage you can get faster, etc. Slow down would of course take time and delta-v, changing observation station would also take them, etc. What interesting is that increasing Isp 10x seems to be doable with the today's/near-future tech, and that would even allow 1000 year mission to the closest star using 3 stages (unfortunately even my napkin breaks though when trying to stretch to the 100 years mission to the star using the today's/near-future tech).
- kibwen 2y agoRight, but assuming constant acceleration, there's an enormous difference between accelerating all the way to the target and only accelerating halfway to the target, and then decelerating the rest of the way.
- bloopernova 2y agoSort of related question: Would space telescopes use interferometry to get a clearer picture? If we had thousands of telescopes spread across the solar system, what sort of images of distant stars/planets/galaxies could we gather? Would such an array be scientifically worth making in our distant future, or does it suffer from diminishing returns?
- jiggawatts 2y agoThere have been plans drawn up for space telescopes flying in formation to do the same kind of interferometry thing as the Keck observatory. The problem is that even far from the Earth, there are tiny but significant forces pushing the space telescopes around. Solar wind, outgassing, gravitational influences from planets, etc... The precision required to maintain formation is... challenging. E.g.: https://arxiv.org/abs/1907.09583 https://arxiv.org/abs/1907.09583
- gus_massa 2y agoWhy do you need to maintain formation? Can the just fly randomly and fix the problem storing the info and a software that gets the positions and calculate the delays? For radio frequency I think it's possible. For visible light, I guess you must do the interference using very accurate mirrors to aim to the central point and that move slightly forward and backward to get the correct phase shift. I think it's not impossible, but very difficult.
- jiggawatts 2y agoYou might be able to capture the phase information for very long IR wavelengths using something like Rapid Single Flux Quantum (RSFQ) circuitry, but I doubt it would be practical. One issue would be that the data volume would be absurd, likely petabytes per second. Practical observations where this would be useful would require long integration times of many hours.
- gus_massa 2y ago
- consumer451 2y agoThe most complete plan for this was proposed by JPL's Slava Turyshev and team. It has been selected for Phase III of NASA Innovative Advanced Concepts. [0] > In 2020, Turyshev presented his idea of Direct Multi-pixel Imaging and Spectroscopy of an Exoplanet with a Solar Gravitational Lens Mission. The lens could reconstruct the exoplanet image with ~25 km-scale surface resolution in 6 months of integration time, enough to see surface features and signs of habitability. His proposal was selected for the Phase III of the NASA Innovative Advanced Concepts. Turyshev proposes to use realistic-sized solar sails (~16 vanes of 10^3 m^2) to achieve the needed high velocity at perihelion (~150 km/sec), reaching 547 AU in 17 years. > In 2023, a team of scientists led by Turychev proposed the Sundiver concept,[1] whereby a solar sail craft can serve as a modular platform for various instruments and missions, including rendezvous with other Sundivers for resupply, in a variety of different self-sustaining orbits reaching velocities of ~5-10 AU/yr. Here is an interview with him laying out the entire plan.[2] It is the most interesting interview that I have seen in years, possibly ever. [0] https://en.wikipedia.org/wiki/Slava_Turyshev#Work https://en.wikipedia.org/wiki/Slava_Turyshev#Work [1] https://www2.mpia-hd.mpg.de/~calj/sundiver.pdf https://www2.mpia-hd.mpg.de/~calj/sundiver.pdf [2] https://www.youtube.com/watch?v=lqzJewjZUkk https://www.youtube.com/watch?v=lqzJewjZUkk
- deleted 2y ago[deleted]
- potamic 2y agoA 6 month integration time is going to generate massive amounts of data. How do they intend to receive all this back from 500 AU away?
- tomtom1337 2y agoWell, one single long exposure would literally generate a regular sized image. Though I do guess they’ll be doing multiple exposures if only to avoid saturating their dynamic range. Does anyone know what a typical number of acquired frames is for a space telescope?
- andy_ppp 2y ago
- cryptoz 2y agoI’ve put this in my “other ideas” section in YC applications for a couple rounds now. No luck yet. Would love to send 1,000 probes to 550AU+ out in order to observe 1,000+ ‘nearby’ exoplanets, hopefully find life, make contact, start trade…haha. Or otherwise defend the solar system from invaders that are perhaps already on the way! Maybe YC rejects me specifically because I put that there…hm.
- bensandcastle 2y agohow much analysis have you done on this? I'm working on a series around Kardashev II work - space solar, asteroid mining, dyson spheres and the real work that is happening to support this now. contact me if you'd like to discuss - @bensand on X
- cryptoz 2y agoSadly I am still at very early stages of this idea. However I will save this thread and contact you if I make progress!
- dylan604 2y agoWhat kind of ROI would attract a VC to this kind of project? How could they monetize it? Would each image created be proceeded by ads that you can skip after 5s or would they be unskippable? Data harvesting is kind of the point of the platform, but maybe they could track that data and get the PII/deanonymized information? "This user spent 104 hours continuously staring at the sun. Maybe they would be interested in sunglasses, or maybe some sun block"
- Cthulhu_ 2y agoI mean it's a great idea and all and probably not original, but it needs billions if not more in new spacecraft that can travel 3-4x as far as the furthest human-made object is (Voyagers) in a reasonable time, a scalable launch system that can launch the probes (1000x payload + fuel with the delta-V required to get there), probes that go to the destination, and a new almost interstellar communications network to get the data and commands there and back again. Basically your idea would be the biggest, most expensive and longest undertaking in space exploration system, ever. I can see why investors would be a bit hesitant about that.
- tombh 2y agoChristian Ready made a great video on his Youtube channel, Launch Pad Astronomy, about NASA's plans for a solar gravitational lens. It's got some great graphics and visualisations, and is accessibly narrated. I was inspired and learnt a lot of new ideas. https://www.youtube.com/watch?v=NQFqDKRAROI https://www.youtube.com/watch?v=NQFqDKRAROI (23 minutes)
- holografix 2y agoIs this a similar principle to the concept in the 3 Body Problem series of books? As in, how one of the main characters is able to boost the transmission power of an earth bound antenna
- onjectic 2y agoFrom my layman understanding, yes, this concept should be bidirectional.
- marmakoide 2y agoIt's not a way to boost a signal. It's using the Sun as a (gravity) lens, with probes at the focal point to gather the image. Because it's a very large lens, that's allow to have a massive zoom on whatever object we are interested in.
- gus_massa 2y agoBut you should be able to use it as a "parabolic" mirror, to make a very directed ray to the planet. (Assuming diffraction is not a problem.) (Assuming no time delay, because to see the planet you should look to were it was many years ago, but to send a message you should aim to where it will be many years in the future.) (Assuming I'm not missing a few more technical problems that are not impossible to solve, but extremely difficult.)
- largbae 2y agoWouldn't you have to have very accurate information about where the planet is going to be when the light arrives?
- verzali 2y agoIn the three body problem she uses some property of the Sun's internal layers to amplify the signal. In reality we don't know of any actual property in the Sun that could do this. The gravitational lens idea is different, it makes use of a known phenomenom where the Sun's gravity "bends" light rays moving around it, which can amplify the light coming from far away objects. In principle you could run it backwards, so the lens could amplify signals we send as well.
- pfdietz 2y agoOne could also lens neutrinos using the Sun's core. Because neutrinos are not absorbed by the Sun, there is a critical offset from the core where they are maximally focused. This would form a caustic, and would cause increased magnification of the neutrino signal at that focal distance.
- JoeAltmaier 2y agoWhat non-uniform field of neutrinos would one expect? I seem to recall that neutrinos come from every direction. Perhaps some stellar event like a nova? Otherwise the image would be the same everywhere, as the sun is relatively uniform.
- pfdietz 2y agoThere should be many concentrated neutrino sources, for example active galactic nuclei.
- est31 2y agoThe sun is the biggest neutrino source in the sky. So we'd need some way to filter out neutrinos that are not from the sun, like we do with various photon telescopes. Furthermore, we can barely detect neutrinos. Building neutrino detectors is extremely challenging. Usually they are extremely massive and surrounded by lots of rock (even more massive). We'd have to get all that mass to the focal point of the observatory which is extremely far away. Lastly, the gravitational field inside the sun is much different than outside. In fact, the field is strongest at the surface (or slightly below, as it doesn't have equal density). The further inside you go, the more parts of the sun start pulling you outside, until you reach the center of mass, where the gravitational forces cancel out.
- akaru 2y agoCan you please elaborate? I find myself making up reasons why but I am certainly wrong.
- 2y ago
- tzs 2y agoHere's a PBS Space Time episode [1] from a couple years ago that describes a couple different proposals for how to do this that take quite different approaches. It starts getting into the specifics of those approaches at 7 minutes in if you don't need the introductory material. [1] https://www.youtube.com/watch?v=4d0EGIt1SPc https://www.youtube.com/watch?v=4d0EGIt1SPc
- codesnik 2y agoaiming it and keeping it on target would be pretty hard, though. And time-consuming, to say the least.
- pmayrgundter 2y agoHere's a little project looking at a related concept using multiple stars https://github.com/celestiary/mglt https://github.com/celestiary/mglt
- M95D 2y agoBut if they want to observe planets, and planets move, wouldn't the telescope need to move too, to keep the image stable while gathering more photons? I presume very few photons reach the telescope from that far away. That means the object's orbit need to be known before beginning it's observation, and then consuming a lot of propellant to change the telescope's speed and trajectory, possibly distance to Sun too, to track another object. At that distance from the Sun, to track objects in another solar system, it would need to move vast distances sideways possibly taking hundreds of years.
- rob74 2y agoThis video linked by another commenter explains it quite well: https://www.youtube.com/watch?v=NQFqDKRAROI https://www.youtube.com/watch?v=NQFqDKRAROI Basically, it's possible to generate an image of an exoplanet, but "retargeting" the telescope(s) to observe another object is not feasible. So you'd better make sure the target that the mission will focus upon is actually worth the attention it gets - but there are other planned telescopes that will be capable of generating data that will allow selecting potential candidates.
- LeifCarrotson 2y agoYes, the planet (hypothetically, a very earth-like planet with a 1-year, 1 AU orbit, 24-hour rotation, and 23-degree tilt at 4 light years' distance like Proxima Centauri b) moves at most 2 AU in a 6 month integration, and the telescope ~700 AU behind the center of the lens would have to move more to keep it opposed. But that 4 light year distance means it's 250,000 AU from the Sun, so some basic geometry says it only has to translate laterally by on the order of 2 * 700 / 250,000 = 0.0056 AU. You're right that that is far larger than an image sensor would be, and larger than the solar sails that would push this craft would be, but inconsequential for a vehicle that's just flown 700 AU. Planets not only move relative to their star, but they also rotate and tilt. I see a number of artists' depictions of the planet (eg at [1]) that look like the satellite just flew into space, illuminated a circular planet with a giant flash bulb, and returned a pixellated photo. I've only thought about this for a minute, but I don't think it would look anything like that. Trying to integrate an image of over the course of a 6-month exposure means not only tracking where the planet is in its orbit but also discerning the longitude on the planet from which a given photon was emitted at a particular time. Plus, if it's tilted at all, we might get many images of the north pole and none of the south pole, or an underexposed image of some polar regions that were only aligned with us for a small duration of the exposure. Finally, even though this gravitational lens is enormous and can collect many more light rays that happen to be aimed at the sun on the image sensor than a physical lens or mirror could, light still has to come from somewhere - specifically, the host star, so only half of the sphere can potentially receive photons that might bounce in our direction at any time, and that half may or may not be aligned with us. Finally, over the course of 6 months, the planet might experience seasons, with changes in the atmosphere and surface ice! Assembling the raw data into a sharp image would be far more challenging than just opening and closing a shutter then grabbing a serial stream of X by Y pixel data from an image sensor, but the output might be much more than a single image. [1] https://www.nasa.gov/general/direct-multipixel-imaging-and-spectroscopy-of-an-exoplanet-with-a-solar-gravitational-lens-mission/ https://www.nasa.gov/general/direct-multipixel-imaging-and-s...
- greg234 2y ago*the daily mail has entered the chat*
- NoMoreNicksLeft 2y ago> Light coming from an exoplanet would be gravitationally focused by the sun with a focal point in the region of about 550 AU to 850 AU, Ouch. Does this mean we're limited to targets located in our plane of ecliptic? Also, we have to have a good target picked out don't we? There's no way to point this at a more interested planet if the first is a bust.
- lazide 2y agoEcliptic - technically no, practically yeah (time/energy wise to change planes will be higher). Picking a good target is also a good idea for the same reason.
- irrational 2y agoHow would this kind of thing work in practice? You move the telescope out to 500AU, and then... what? I assume the telescope would have to line up a potential star system with our sun in a direct line. So the telescope would have to move around until everything is lined up. Then I presume it would need to take a wide angle view of that star system to look for a likely planet. Would it need to move closer or farther away from our sun to get a wider field of view? Once it found a suitable planet, I presume it would need to collect light from that planet over an extended period of time, say 6 months. But, the planet is moving during those six months. How does the telescope keep the planet in view? Is the telescope constantly moving to keep pace with the planet? How much fuel would we have to send out there with the telescope?
- BurningFrog 2y agoThe planet is also rotating, so how do you keep a specific 10 square kilometers part of it in focus?
- BurningFrog 2y agoMaybe you can observe it over a long time, and you'll note that the data repeats every N hours. That must be the rotation time, and then you can find the corresponding "pixel" for each rotation and work with that data. Sounds like several near impossible problems on top of each other though.
- mapt 2y agoIf you want to use this method, you're basically going to require one spacecraft per target and a decade of lead time for a very short-duration observation. This is not necessarily a deal-breaker; Meaningful scientific inquiry would just require we mass produce them. We already sabotage ourselves in astronomy by refraining from mass production approaches for political reasons. There is no practical amount of fuel that can get you to 500AU on a simple trajectory. What seems to be the best option for setting massive vehicles on a solar escape is a sequence that looks something like: * Launching to Jupiter propulsively * Cancelling out most solar-orbital velocity there using a gravity assist in order to dive down into a sun-skimming orbit * Burning through a large solid state rocket kick stage while at close approach to the sun from behind a heat shield. The Oberth Maneuver. * (optional) unfurling an electric sail or solar sail once the rocket has finished as you're speeding away from Sol Together that gets you the required ~100AU/year escape for a mass fraction that is tractable for our civilization.
- capitainenemo 2y agoI mean, the challenge of putting a telescope that far out is a pretty big one. The New Worlds Imager proposal is a lot simpler to implement and maintain and could be made more powerful by incrementally adding new satellites to the array. Although their proposal doc says "to truly study the surfaces in detail, the way missions like LandSat have of the Earth would take very large apertures, on the order of a square kilometer. This is unlikely to be become affordable in the foreseeable future" - still building an enormous synthetic aperature with a huge fleet of telescopes vs building a telescope that far out? I dunno... SpaceX is dropping the cost to launch a lot.. And based on their proposal docs, just a few telescopes would be able to image at 100km resolution. Bonus, it'd be able to image a lot more targets since it wouldn't need the sun to be in the right place. https://newworlds.colorado.edu/info/ https://newworlds.colorado.edu/info/ http://newworlds.colorado.edu/info/documents/gsfc_February%202007.ppt http://newworlds.colorado.edu/info/documents/gsfc_February%2... https://newworlds.colorado.edu/info/documents/FinalReportNewWorldsImagerMarch312005.pdf https://newworlds.colorado.edu/info/documents/FinalReportNew...
- metalman 2y agoLifting mass into any planetary or solar orbit is now in the pist mechzilla,chopstick era. 2022 had more in common with the apollo missions,and is no longer relevant.Mass and physical size constraints have changed dramaticaly,and costs are in free fall. What is relevant is ,are the words "solar lense" bieng whispered by Elo (he does not need the "n" as he is now a 3 letter agency all by himself) and its that agency and the lift to orbit capability that could have everyone looking over Elo's shoulder while he fiddles with the knobs and brings an extra solar planet into focus for the first time. All for much less than its costing him to fiddle with the geo political knobs,which he does not seem to enjoy much anyway