1. https://en.wikipedia.org/wiki/Solar_gravitational_lens
2. https://www.nasa.gov/general/direct-multipixel-imaging-and-s...
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.
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.
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 is indeed spherical frictionless cow-ly possible if we spend a trillion dollars to increase ORNL's annual Pu production capacity so that it doesn't take 200 years to make 600kg of Pu-238.
When someone demonstrates a complex device (let's set aside power generation how about a valve? Or a capacitor?) that can last a century in space I'll agree that it is actually possible.
That's what "current level of technology" means. The lego bricks exist, now, today, preferably in stock ready for immediate shipment on Digikey, and can be snapped into place.
Producing 600kg of Pu-238 is entirely technically feasible with current level of technology, as it has already been done when the US and USSR built their stockpiles.
Current level of technology means things we are capable of achieving right now, it does not mean that the pieces literally exist ready to use, unless you genuinely believe that the thousands of satellites orbitting our planet are not part of the current level of technology because they're purpose built without using off-the-shelf parts.
Oh come on, we used to make so much more of it.
I see estimates that it costs 4 million dollars per pound, plus some scaling costs?
A trillion dollars is not even close to "spherical frictionless cow" when the benchmark is "humanity's current technological capabilities", and a few billion is basically nothing at that scale.
> When someone demonstrates a complex device (let's set aside power generation how about a valve? Or a capacitor?) that can last a century in space I'll agree that it is actually possible.
Is a bunch of stuff lasting 50 years not good evidence? What is your threshold for "demonstrate", do we have to wait 200 years before you can be convinced?
But also, there are other radioisotopes besides the one currently used. The ~90 year half life of the current normal radioisotope is great for current missions, not the only option.
Makes them worse unless and until you make the shielding several times thicker than anything you'd be able to launch from the ground. Watched one science program that demonstrated it beautifully where the interviewee stuck several balloons on a board and shot at it with a high-powered rifle, popping just one. Then he stuck a metal plate in front of the balloons and shot it, and the resulting shrapnel popped all the balloons behind it. That's a cosmic ray hitting shielding.
That's also an unsolved problem with any Mars trip. Electronics can be built redundantly to recover from cosmic ray hits. Humans not so much.
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
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.
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?
Of all the possible space probes or missions we could do. I want this one more than any of them!
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.
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.