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.

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/].

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.

It wouldn't take nearly that long. The proposal is to use solar sails. There is a nice video about the details on YouTube: https://www.youtube.com/watch?v=NQFqDKRAROI

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?

Let's say you build single photon detectors and ultra precise time stamping. Would that get us near? Today, maybe we don't have femtosecond time stamping and detectors yet. But that is something I can imagine being built! Timing reference distribution within fs over 100s of km? Up to now, nobody needed that I guess.

I don't know the details of how it works, but synthetic aperture radar works thanks to the motion of the satellites, so there must be some situations for which simultaneity isn't required.

That the stars are beyond reach might be depressing, how aggresively we are gambling our little boat is on the other hand actively scary and perhaps the dominant limit on humanity's effective reach.

Further more I don't think technologically advanced civilizations will be wasting their time and resources in colonizing new works, space is simply too big for that. And that they would conduct their explorations with telescopes, not probes, space is simply too big for probes.

Just to ring the point home, we are technically (but not yet economically) capable of creating small telescopes which use our sun as a gravitational lens, which would be able to take photographs of exoplanets. In the far future we could potentially build very large telescopes which can do the same and see very distant objects with a fine resolution. That would be a much better investment then to send out self replicating robotic probes.

Orbital mechanics, orbital period, and minimum determinable arc of JWST.

Though another thought is that doppler might also reveal velocity, if a spectrum could be obtained. Since the system is nearly perpendicular to the Solar System (we're viewing it face-on rather than from the side), those shifts will be small.

https://en.wikipedia.org/wiki/Nancy_Grace_Roman_Space_Telesc...

> In April 2025, the second Trump administration proposed to cut funding for Roman again as part of its FY2026 budget draft. This was part of wider proposed cuts to NASA's science budget, down to US$3.9 billion from its FY2025 budget of US$7.5 billion. On April 25, 2025, the White House Office of Management and Budget announced a plan to cancel dozens of space missions, including the Roman Space Telescope, as part of the cuts.

In sci-fi we see warp drives, worm hole travel, phasers, photon torpedos and energy shields around ships. But what if none of that is possible? In that case, we might even have the technology to defend ourselves today if we manage to detect the attack in time.

It's a huge risk for a civilization to attack us. Even if they have capabilities that are beyond our technology, there might still be limitations based on the laws of physics. And if they attack us, they risk a response.