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Mission to reach and operate at the focal region of the solar gravitational lens
- everyone 4y agoVideo about it by launchpad astronomy https://youtu.be/NQFqDKRAROI https://youtu.be/NQFqDKRAROI
- WithinReason 4y agoStarshade deploying: https://exoplanets.nasa.gov/resources/1015/flower-power-nasa-reveals-spring-starshade-animation/ https://exoplanets.nasa.gov/resources/1015/flower-power-nasa... "The "petals" of the "sunflower" shape of the starshade are designed to eliminate the diffraction that is the central feature of an Aragoscope." "The starshade is a spacecraft designed by Webster Cash, an astrophysicist at the University of Colorado at Boulder's Center for Astrophysics and Space Astronomy. The proposed spacecraft was designed to work in tandem with space telescopes like the James Webb Space Telescope, which did not use it, or a new 4-meter telescope." https://en.wikipedia.org/wiki/New_Worlds_Mission https://en.wikipedia.org/wiki/New_Worlds_Mission
- ramraj07 4y agoThere’s a ton of astronomy YouTube channels but this is now my favorite, dethroned pbs space time. The video that converted me was his supernova explanation https://youtu.be/RZkR9zdUv-E https://youtu.be/RZkR9zdUv-E - for all the content out there no one else has anything this good about supernovae.
- oezi 4y agoThanks, that was nice.
- sandworm101 4y agoA much better idea is the terrascope, using Earth's upper atmosphere as a refracting lens. This wouldn't require a multi-decade mission, nor a huge sunshield. https://arxiv.org/abs/1908.00490 https://arxiv.org/abs/1908.00490
- someguydave 4y agothe sunshield would not be huge at 900 AU
- TomGullen 4y agoAn excellent video on this: https://www.youtube.com/watch?v=jgOTZe07eHA https://www.youtube.com/watch?v=jgOTZe07eHA Earths atmosphere and weather affects this sort of telescope IIRC and will filter out some lightwaves but seems like a much easier win
- e12e 4y agoInteresting. I wonder if there are planets with atmosphere in our solar system that would allow testing this from earth orbit (eg: iss/satellite looking at objects lensed by Jupiter etc, because the refraction and distances work out).
- jcims 4y agoCouple of examples shot from the ISS - https://www.youtube.com/watch?v=1t8UNxY2bgQ https://www.youtube.com/watch?v=1t8UNxY2bgQ
- deleted 4y ago[deleted]
- londons_explore 4y agoThe fact that this telescope takes 30+ years to get into position and take a photo, and that it in its lifespan can only look at a single planet, is a real disadvantage...
- est31 4y agoYou just have to mass produce these things and send them to interesting targets in parallel.
- ur-whale 4y agoOr make the sun heavier to move the focal point closer :-D (aside from the obvious impossibility, would it work? I'm sorta assuming that heavier mass => more distortion => closer focal point. Is that correct?).
- londons_explore 4y agoYes... Or smaller. Light from far enough away is focussed by any mass, and will appear as a 'ring' around the mass. But if the mass isn't heavy enough the 'ring' that you see might be behind the object itself.
- femto 4y agoI wonder if a cluster of stars can be treated as a MIMO scattering channel for more distant unknown objects? If so, it should be possible to resolve details in the unknown object. I guess the geometry would have to be such that there is appreciable signal from each star/scatterer (ie. sort of colinear), but there would be no requirement to be on a focal line?
- pmayrgundter 4y agoNeat idea!
- femto 4y agoI guess one problem could be that the scatterers/stars are luminous, so their own emissions might overpower the scattered signal? Maybe a cluster of darker objects? Or maybe luminous objects are okay if the scattered waves are coming from dark regions surrounding the scatterers and have enough angular separation that they can be resolved from the scatterer's own emissions?
- pmayrgundter 4y agohmm.. right.. if the angle of deflection is low and the star is close enough that its light and deflected light show up very close together. My intuition is this is not the case... remember Eddington's test of relativity was for deflection of starlight around our Sun. We're really close, yet it was observable with the moon obscuring the main sunlight. the article[1] says "For light grazing the surface of the sun, the approximate angular deflection is roughly 1.75 arcseconds." So, what, we take the arcsin of 1.75 arcseconds to get the apparent divergence ratio, and multiply that by distance to stars? As long as that value is larger than the aperture of your camera, then you don't get competing light? Or maybe you'd need something like the TESS satellite, where you have a screen specially created to only allow certain beam transits into your detector. I've worked with a nearest 10k stars database (https://celestiary.github.io/ https://celestiary.github.io/, zoom way out) and the edge of that is about 2k light years away. So very roughly, let's say there's 1/8th of those in a certain direction... so you get.. what? some 2k sample points towards some distant object? But really most of them wouldn't deflect that object's light towards Earth, but usually over or undershoot. Don't really know how to put these together quickly, but is giving me some good food for thought! [1]https://en.wikipedia.org/wiki/Eddington_experiment https://en.wikipedia.org/wiki/Eddington_experiment
- pmayrgundter 4y ago"Using a meter-class telescope one can produce images of the exoplanet with a surface resolution measured in tens of kilometers and to identify signs of habitability." Here's gmaps satellite view at ~10km/px EDIT: fixed permalink https://www.google.com/maps/@41.4220797,-93.7912673,6877284m/data=!3m1!1e3?hl=en https://www.google.com/maps/@41.4220797,-93.7912673,6877284m... also: https://imgur.com/a/JwHmaIY https://imgur.com/a/JwHmaIY Wow.
- bartread 4y agoThat link just opens a standard map of the whole globe in a flat projection - I think you might need to use the sharing link generator to share what you intended.
- simias 4y agoI think that's what they wanted? Although it's still a strange way to communicate that given that it'll change wildly based on screen resolution. A screenshot would probably be a better idea.
- rchard2scout 4y agoI'm not sure if it's possible to easily share the correct settings in an URL, but: In the Layers menu, set it to Satellite, Globe view, and turn off Labels. Then, zoom until the earth is ca. 1275 pixels wide
- abhaynayar 4y agoI think the link intended to show 10 km/pixel, to give an idea of what it would look like. It shows a scale of length 1000 km to me, if it is 10 km/pixel then there should be a 100 pixels within that length, which seems okay as a sanity check. But yeah, it depends on the screen resolution as well.
- pmayrgundter 4y agoThanks, fixed!
- pmayrgundter 4y ago
- Brian_K_White 4y agoBefore I read this... "focal region" sounds nonsensical to me. Surely the focal length and direction depends on the thing you want to look at? The "focal region" would be something like a sphere starting some distance from the sun and extending out in all directions to infinity?
- WithinReason 4y agoI think that's why it's called a focal region instead of a focal point.
- Orothrim 4y agoI don't believe so, I believe that the size and gravity of the sun have a gravitational effect on space an result in a focusing of light at 500+AU distance from the sun. Hence the focal region is around this sphere and is where you would "sit" to use the sun as a lens and get information about the universe on the opposite side of the sun. https://en.wikipedia.org/wiki/Solar_gravitational_lens https://en.wikipedia.org/wiki/Solar_gravitational_lens
- simias 4y agoGiven the scales we're talking about I presume that everything you want to look at is effectively "at infinity", as such I expect that you consider where two parallel rays would meet due to solar lensing and that's your focal region.
- krisoft 4y ago> Surely the focal length and direction depends on the thing you want to look at? Yes. And "aiming" your observatory involves moving it on that sphere. Given the distances involved that is pretty much either impossible or time prohibitive. The region starts at 548 AU from the Sun. So 548 times the average Sun-Earth distance. In an ideal world you would teleport your camera to this location instantaneously, take a picture and then teleport to the next location to look at something else. We don't know how to do that. The distances are immense. So instead we pick a target, and send out a satellite or satellites on the opposite vector from it to take a peek. There is a single point where the target will be in perfect focus, but in practice (as the paper shows) the target is "in-focus" enough in a larger region that your satellites can take a picture while they fly through the region around the ideal point.
- causality0 4y agosolar sailing technologies and in-space aggregation of modularized functional units to form mission capable spacecraft Am I alone in thinking this is somewhat pointless to discuss before the prerequisite technology is developed? It's a bit like "how to keep your sentient sexbot from deciding to murder you". Like if we could do those things in the first place there would be a thousand applications with a better return on investment than this.
- TremendousJudge 4y agoI'd say it's pretty useful to discuss hypotheticals of all kinds. In this case, generating ideas for uses of a technology that is under development might increase interest and therefore funding, or recruit new people to the cause, and generate new ideas that may be useful for the active development of the technology.
- croo 4y agoWell, Diffe Whitfield envisioned an internet highway around 1974 then went on to find out how can we keep secrets when everyone has a computer in his home.
- rendall 4y ago> somewhat pointless to discuss before the prerequisite technology is developed From the article "The study reveals elements of such a challenging mission, but it is nevertheless found to be feasible with technologies that are either extant or in active development." (emph. mine) It's pointless to discuss the application of technologies in active development? > there would be a thousand applications with a better return on investment than this You veered into a baffling non-sequitur, there. ROI in a unique science mission to image an exoplanet 100 l.y. distant to a resolution of 10s km for potential human habitation? The successful ROI is incalculable.
- krisoft 4y ago> Am I alone in thinking Probably not. Most people have trouble thinking long term. > this is somewhat pointless to discuss before the prerequisite technology is developed? People wouldn't develop said prerequisite technologies if there are no applications for it. This paper shows that if we would have those technologies we could get this neat thing. > there would be a thousand applications with a better return on investment than this. Name them.
- hamter 4y agoFor those like me who need some kind of reference for the distances mentioned (548-900 AU), Voyager 1 is 156.5 AU from earth today.
- quirkot 4y agoFor those looking for a live look at Voyager status: https://voyager.jpl.nasa.gov/mission/status/ https://voyager.jpl.nasa.gov/mission/status/
- alexpotato 4y agoThe solar system explorer view they have on that page is fantastic! I recommend clicking on the "solar system" toggle in the bottom middle of the view. It gives you a real sense of the planets, probes, asteroids etc that are flying around our solar system. Also reminds me of looking at air traffic control maps and what that might look like once intra-solar system space travel becomes routine.
- deleted 4y ago[deleted]
- scotty79 4y agoI wonder how much faster we could get there with solar sail and laser boost from Earth
- ben_w 4y agoWithout specifying the size of the laser, anything from "even slower" to "whole trip in just under 16 days". https://en.wikipedia.org/wiki/Breakthrough_Starshot https://en.wikipedia.org/wiki/Breakthrough_Starshot http://www.wolframalpha.com/input/?i=548%20AU%2F0.2c http://www.wolframalpha.com/input/?i=548%20AU%2F0.2c
- lazide 4y agoHah, the latter number requiring some significant percent of earths mass being converted to energy or something?
- MichaelMoser123 4y agoAn interview with Dr. Slava Turyshev, who is one of the authors of the paper. They are talking about the project https://www.youtube.com/watch?v=lqzJewjZUkk https://www.youtube.com/watch?v=lqzJewjZUkk
- deleted 4y ago[deleted]
- SideburnsOfDoom 4y agoI think I've read about using a swarm of these probes "at the focal region of the solar gravitational lens" (i.e. in spherical shell starting 548 AU from the Sun) in A Sci-Fi novel. I think this one: https://www.goodreads.com/book/show/13039884-existence https://www.goodreads.com/book/show/13039884-existence
- lstodd 4y ago30 years.. I wouldn't be surprised when a bigger and better telescope launched 10 years later arrives there 15 years before this crazy contraption.
- Cthulhu_ 4y agoMaybe, but only if there's a big leap in propulsion technology, and as far as I know there's not been anything big in that regard in the past 50-odd years. Closest thing is probably reusable rockets to reduce cost.
- skykooler 4y agoThere's a few things that could be used to complete the mission significantly faster with basically-current tech (e.g. NERVA, or Project Orion), but even for deep-space missions they are unlikely to see use any time soon.
- abecedarius 4y agoOn that timescale my bet would be on very large telescopes built in space nearer us (supplanting the ones built on Earth and launched then unfolded). This wouldn't perfectly substitute for a solar gravitational lens scope, but it could do a hell of a lot.
- adg001 4y agoIt seems there are a pretty good deal of ideas for ever more sophisticated imaging technologies. That's nice. However it would be more reassuring to come up, at the same time (or in due course), with a similar supply of clever ideas for more sophisticated rocket engines, or, more likely, with a long series of fundamental contributions to our understanding of physics and biology. The ambition of the proposed mission is to reach a focal region ~548-900 AU away in order to image exoplanets which are distant up to 100 light years. I am sorry to have to remind us all about this, but given the extenuating long journey to reach a region that is not any closer than 548 AU, it would be even more "painful" to discover even more distant exoplanets which would remain beyond reach for all practical purposes – As per me discoveries of such level should remind us to reaffirm our commitment to take care of the only planet we can live for the foreseeable future.
- cptaj 4y agoAstronomy still provides useful insights regardless of whether we can reach those places or not. That said, we are indeed researching ever more advanced propulsion technologies! We've made great strides in electric propulsion, which is far more efficient for long voyages than chemical rockets. This tech is already in wide use today in satellites and probes of all kinds. We're ramping up research in nuclear rocket propulsion again. There are several branches here: nuclear electric, nuclear thermal and nuclear pulse. Of these, the last one is the least developed since it basically means using nuclear explosions to boost you, but it has the most promise for futuristic spaceship drives. There's also the possibility of using antimater pulse drives but that's a hairy can of worms. Very hard to produce the fuel in enough quantities.
- deleted 4y ago[deleted]
- mabbo 4y ago2042: Earth receives a message from an alien intelligent species 32 light years away. 2109: Aliens receive a reply, which includes a map of their own world, including where their largest cities are located. I'm just saying, this is totally a possibility! We can creep on the neighbours!
- multiplegeorges 4y ago> Aliens receive a reply, which includes a map of their own world, including where their largest cities are located. I think we'd interpret this as a threat, maybe, like a target map. They might too. Probably best to reply with something more innocuous, like the Fibonacci sequence.
- dylan604 4y agoyeah, that was my reaction as well. "We hear you, and just letting you know, we know where you live and have started targeting solutions. Just so you know, we're all armed down here!"
- dwringer 4y agoIf the aliens are as willing as we are to interpret everything through a lens of violence then we likely have no chance in the first place IMHO.
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- walnutclosefarm 4y agoIt's an interesting idea, and why not write a paper about it and try to get it published? Every academic needs papers with their name on them, and thinking about this had to be fun, if you don't have anything useful to do with your time. But as an actual scientific investment, in my opinion, it belongs pretty near the bottom of pile of things we should spend our astronomy / cosomology / astrophysics budget on. The cost per unit of new information is just way too large, and the risk of mission failure too high, to justify making it a priority.
- superkuh 4y agoIt's not a new idea and there already have been dozens of papers, and entire books (http://erewhon.superkuh.com/library/Space/Spacecraft/Deep%20Space%20Flight%20and%20Communications_%20Exploiting%20the%20Sun%20as%20a%20Gravitational%20Lens_%20Claudio%20Maccone_%202009.pdf http://erewhon.superkuh.com/library/Space/Spacecraft/Deep%20...), published about using the solar gravitational focus as a lens and sending a spacecraft there. In fact NASA was already funding early mission studies like the Heliopause Electrostatic Rapid Transit System (HERTS) a decade ago. And not only is it good for planetary sciences, it's good for cosmology too since it enables looking at the truly small scale structure of the cosmic microwave background. A mission to the gravitational focal line opposite some star should be one of the highest priorities. http://erewhon.superkuh.com/library/Space/Spacecraft/Diffraction%20of%20electromagnetic%20waves%20in%20the%20gravitational%20field%20of%20the%20Sun_%20arxiv170406824.pdf http://erewhon.superkuh.com/library/Space/Spacecraft/Diffrac... http://erewhon.superkuh.com/library/Space/Spacecraft/Direct%20Multipixel%20Imaging%20and%20Spectroscopy%20of%20an%20Exoplanet%20with%20a%20Solar%20Gravity%20Lens%20Mission_%20Turyshev%20et%20al_%20arxiv2002.11871.pdf http://erewhon.superkuh.com/library/Space/Spacecraft/Direct%... http://erewhon.superkuh.com/library/Space/Spacecraft/Image%20recovery%20with%20the%20solar%20gravitational%20lens_%20arxiv2012.05477.pdf http://erewhon.superkuh.com/library/Space/Spacecraft/Image%2... http://erewhon.superkuh.com/library/Space/Spacecraft/Mission%20to%20the%20Gravitational%20Focus%20of%20the%20Sun_%20A%20Critical%20Analysis_%20arxiv160406351v1.pdf http://erewhon.superkuh.com/library/Space/Spacecraft/Mission... http://erewhon.superkuh.com/library/Space/Spacecraft/Photometric%20limits%20on%20the%20high%20resolution%20imaging%20of%20exoplanets%20using%20the%20solar%20gravity%20lens_%20Phil%20A%20Willems_%20jactaastro%202018.pdf http://erewhon.superkuh.com/library/Space/Spacecraft/Photome... http://erewhon.superkuh.com/library/Space/Spacecraft/Resolved%20imaging%20of%20exoplanets%20with%20the%20solar%20gravitational%20lens_%20arxiv2204.04866.pdf http://erewhon.superkuh.com/library/Space/Spacecraft/Resolve...
- sp332 4y agoThis would also work for radio waves, right? We would be able to listen in on radio broadcasts from a distant planet.
- spacemark 4y agoYes, it's possible but the refractive index decreases with increase in wavelength to the point that this would not be feasible. Radio wavelengths are ~9 orders of magnitude larger than optical, meaning the detector would need to be placed roughly 30 light years from earth. A bit out of our reach. (assuming I did my back of the envelope math right)
- ur-whale 4y agoUh, never realized that gravitational lensing was stronger for higher frequencies ... is that a fact? Any reference? [EDIT]: the formula on page 4 of the book below does not seem to have a frequency parameter ... Also, they seem to consider that objects worth looking at are at infinity, which is why there is a well-defined focal distance from the sun. What seems to involve frequency is that the gain of the lens varies (same book, page 9). http://erewhon.superkuh.com/library/Space/Spacecraft/Deep%20Space%20Flight%20and%20Communications_%20Exploiting%20the%20Sun%20as%20a%20Gravitational%20Lens_%20Claudio%20Maccone_%202009.pdf http://erewhon.superkuh.com/library/Space/Spacecraft/Deep%20...
- spacemark 4y agoOops my bad, thought this was a comment under another thread discussing terrestrial lensing which uses Earth's atmosphere, not gravitational lensing. Disregard!
- DennisP 4y agoI wonder whether any stars 30 light years away have interesting objects behind them.
- sp332 4y agoBut we're using a lens that bends spacetime. I'm not sure index of refraction is relevant. On the recent image from JWST, I don't see any refraction artifacts on the lensed images of galaxies. https://www.nasa.gov/image-feature/goddard/2022/nasa-s-webb-delivers-deepest-infrared-image-of-universe-yet https://www.nasa.gov/image-feature/goddard/2022/nasa-s-webb-...
- garettmd 4y agoCan someone ELI5 for me?
- MattPalmer1086 4y agoUse the sun's gravity as a giant lens (bends light) so you can see a really long way away. But the focal point of this lens is about 500 times the distance of the earth to the sun, so difficult to get to.
- swamp40 4y agoWhat does the focal region of a 3 dimensional solar gravitational lens look like?
- Archelaos 4y agoAre trajectories possible that bring the satellite into the focal points of more than one expolanet, either of the same or a different target system?
- ur-whale 4y agoIsn't that focal "region" actually a heliocentric sphere? If so, where on that sphere would we place the scope? Or would it sorta glide on that sphere to be able to look at a specific points in the universe?