A solar gravitational lens will be humanity's most powerful telescope

The 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

[1] https://www2.mpia-hd.mpg.de/~calj/sundiver.pdf

[2] https://www.youtube.com/watch?v=lqzJewjZUkk

Christian 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 (23 minutes)

Is 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".

How 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?

One 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.

But 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.

Lifting 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

Here'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

I’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.

Is 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

> 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.

Sort 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?

I 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/ http://newworlds.colorado.edu/info/documents/gsfc_February%2... https://newworlds.colorado.edu/info/documents/FinalReportNew...

Here's a little project looking at a related concept using multiple stars

https://github.com/celestiary/mglt

This 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?

Could 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?

aiming it and keeping it on target would be pretty hard, though. And time-consuming, to say the least.

*the daily mail has entered the chat*

Spoiler: the focal point is 3.5x the distance to Voyager 1.