5 ms·
We can do better than that! Using the Sun as a gravitation lens[1], and a probe at a focal point of 542 AU, we could get 25km scale surface resolution on a plan
by GolfPopper 1y ago
We can do better than that! Using the Sun as a gravitation lens[1], and a probe at a focal point of 542 AU, we could get 25km scale surface resolution on a planet 98 ly away. [2] This would be an immense and time-consuming endeavor, but does seem to be within humanity's current technological capabilities.
1. https://en.wikipedia.org/wiki/Solar_gravitational_lens https://en.wikipedia.org/wiki/Solar_gravitational_lens
2. 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...
- JumpCrisscross 1y agoDo we have a recent cost estimate?
- twothreeone 1y ago"We used to look up at the sky and wonder at our place in the stars. Now we just look down, and worry about our place in the dirt."
- sho_hn 1y agoIt's cynical to assume OP was gunning for "it's too expensive". They might just want to know the size of the challenge to get it done.
- twothreeone 1y agoAnd it's ironic to scold others for missing a point while missing their point. All good though.
- amanaplanacanal 1y agoI missed it too. What was your point?
- JumpCrisscross 1y agoI’m genuinely curious what it would cost given recent launch-cost and fabrication advances. If above $10bn, we should keep working on those inputs. If below, it strikes me as more promising than another circular collider.
- bigiain 1y agoI'd guess less then 1 or 2 hyped AI startup valuations that eventually collapse to nothing.
- thiht 1y agoAnd more importantly, a story points estimate (t-shirt sizing is obviously XL)
- ainiriand 1y agoLets get an epic ticket ready.
- kilroy123 1y agoI was going to post the same exact thing and links. Of all the possible space probes or missions we could do. I want this one more than any of them!
- GMoromisato 1y agoAgreed! This might be easier than an interferometer. You just need a lot of delta-v
- cedws 1y agoHow do you decelerate once you get there though?
- GMoromisato 1y agoBy “delta-v” I mean propellant budget, not initial velocity. So you spend half your delta-v to accelerate out and the other half to decelerate. But of course, the initial delta-v costs a lot of propellant because it has to push an almost full tank. By the time we have to decelerate the ship will be a lot lighter. That’s why you needed a full Saturn 3rd stage to send Apollo to the moon, but just the service module to get back to Earth. I realize now that “a lot of delta-v” is an understatement. 500 AUs is ridiculously far. To get there in under a century you’d need fission-fraction reactors, well beyond our current tech.
- kadoban 1y ago> I realize now that “a lot of delta-v” is an understatement. 500 AUs is ridiculously far. To get there in under a century you’d need fission-fraction reactors, well beyond our current tech. Voyager 1 is 166 AU away, it launched about 50 years ago. So wouldn't we just have to do about twice as well as that, or launch 2 of them in opposite directions? That sounds _very_ hard (Voyager is amazing), but it can't be beyond our current tech, right? We did fairly close to that 50 years ago.
- os2warpman 1y agoA maintenance-free power source capable of lasting the 200 or so years it would take to make it to 542 AU does not seem within humanity's current technological capabilities. Parker at its highest velocity could make it there in a century, but it doesn't have to slow down and stop. Or station keep. When we have a power source that can do 5kW (I just doubled Hubble, 542 AU would probably require much more for communications) for 100 years I'll agree that its design can be refined and its lifespan extended to 200 and 542 AU is within our reach.
- dotnet00 1y agoWith distances that big, is it even necessary to slow down much? The depth of focus is probably a couple dozen AU? Even if it takes the probe a century to get there, if you can squeeze a decade or two of observation out of it without slowing down, there's no reason to bother and instead send a new upgraded telescope every decade or so. As far as power requirements go, assuming a doubled power demand from Hubble might be a bit excessive. A telescope that far out would have to be nuclear powered, so thermal regulation is 'free'/passive and RCS load is reduced (don't have to constantly adjust to point away from the Earth), which I expect are the biggest power draws on Hubble. If we assume a 150 year lifetime, with a 3kW draw by EOL and current RTG tech... RTGs have ~6% efficiency, so for 3kW electricity, you need 50kW in heat. RTG electricity output drops ~2% per year, so after 150 years, you have 5% of the initial electrical output, and you get ~0.57W/g of Pu-238. Meaning, you need ~600kg of it to power the telescope this way [https://www.mathscinotes.com/2012/01/nuclear-battery-math/ https://www.mathscinotes.com/2012/01/nuclear-battery-math/]. That's not a politically feasible amount, but it's not technically impossible with current/near future tech whose development could be spurred on by serious interest in this kind of mission. 'Proper' fission reactors can also do the job, you get higher efficiency and don't have to run the reactors for the entire 150 years besides accounting for decay (e.g. an RTG that needs to provide enough power to keep some clocks running, the electronics and batteries warm, and trigger whatever mechanism would start up the reactor). Probably less than 100kg of Pu-238 just by better reactor efficiency.
- ycui1986 1y agoi don't think modern semiconductor device will last more than 100 years, even without all the radiation. making something last more than a few decades is very hard.
- nandomrumber 1y agoFor scale, Voyager 1 is about 167 AU away.
- seanhunter 1y agoYou’re never going to break into popular science reporting with that sort of attitude. If you are going to do the scale of a small thing, you have to compare it to the size of a banana or the width of a hair if it’s very small. For larger things, “football pitches” are the standard, although “blue whales” and “double-decker busses” are also acceptable units in some circumstances. So, for scale, Voyager 1 is about 2.5 x 10^11 regulation football pitches away although they vary in size so it could be anywhere between 2.08 x 10^11 and 2.8 x 10^11. Now, see how much more relatable that is for a common person?
- nandomrumber 1y agoSmoots https://en.wikipedia.org/wiki/Smoot https://en.wikipedia.org/wiki/Smoot
- xg15 1y agoWe should definitely use TeraSmoots more as an astronomically unit.
- nandomrumber 1y ago1 AU is 0.879 TeraSmoots
- rishav_sharan 1y agoI think Tipping of the Cool Worlds youtube channel did a video that we can just use earth for the gravitational lensing and that would be far cheaper https://m.youtube.com/watch?v=jgOTZe07eHA https://m.youtube.com/watch?v=jgOTZe07eHA
- ycui1986 1y agoThere are also alternative proposals to use Earth's atmosphere refraction for focusing, in a geometrically similar fashion as gravitational lens. It seems more feasible than using Sun's gravitational lensing. https://en.wikipedia.org/wiki/Terrestrial_atmospheric_lens https://en.wikipedia.org/wiki/Terrestrial_atmospheric_lens
- le-mark 1y agoDoes size of the planet matter? How about using Saturn or Jupiter?
- Balgair 1y agoYes, the larger the object you're using as a lens, the better the image. This is due to the 'Lens Makers' Equation'. Larger objects like Earth, Jupiter, or the Sun would make for larger radii and therefore better resolution.
- Intralexical 1y agoHas anyone explored using the target planet's mechanical motion? As it rotates and orbits, a different part of it will be lit up every hour (and every season). You only get a single pixel at once, but that pixel is localized to a region that scans across the whole surface over time. For something Earth-like, I think you could definitely make out the Americas, Asia, and probably Africa. Maybe both of the ice caps too, depending how it's oriented and if you're capturing spectra. ...Somebody should mock up a solver in Python. I'm sure there are other tricks you could use. Diffraction limit schmraction schmidit, real planets aren't point light sources.
- j_not_j 1y agoWouldn't be worth the trouble to try. Why, you ask? How do you point it? Where do you point it? You have a "telescope" with a field of view of one-planets worth of pixels. But the planet is in orbit, so it drifts away from the imaged field of view within minutes. Meanwhile your sensor is travelling away from the "lens" so transverse velocity would be needed to track the orbit at a delta-v and direction that is unknowable. Unknowable, because you have to know where the planet is, within a radius, to put your "sensor" in the right place in the first place. Imagine taking a straw, place it in a tree, walk away a few km and focus a telescope on the straw and hope to look through the straw to see an airplane flying past. You have the same set of unknowables.
- __MatrixMan__ 1y agoI won't argue that it would be worth the effort, but it would be interesting to set something like that going and just keep scanning. A few years worth of data might turn up interesting things even if it wasn't particularly useful for finding those things a second time.
- catlifeonmars 1y agohttps://arxiv.org/abs/2506.20236 https://arxiv.org/abs/2506.20236