Yeah, the solar lensing point is WAY the hell out there: since 1 AU is 8 light-minutes, so the 548 AU minimum works out to 73 light-hours away. When LIGHT takes half a week to make a one-way trip, you're in the deep space boondocks, folks.
I haven't read the paper yet, but this thing would have to have a fair amount of nuclear power, and comms would be a challenge as well. As the abstract mentions, though, while the project has a high degree of difficulty, there appear to be no complete technology showstoppers to actually doing this, so it's at least as doable (and considerably cheaper than) a von Braun-style centrifugal space station in Earth orbit.
It'll be interesting to see if the idea gets any traction...
The 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.
One issue would be slowing down when you get there.
You'd need to carry a deployable/detachable mirror with you to reflect the laser back at the craft, but that mirror itself would also get accelerated further out, which means having to correct for that, etc., etc.
With a solar sail you can "tack" by reflecting photons against your tangential velocity – but that only works if the tangential component is indeed what you want to shed. Getting rid of radial velocity is more difficult, and in a hyperbolic (escape) orbit radial is mostly what you have.
Not really, it's the velocity the "Breakthrough Starshot" probes would reach. They propose[1] that launching each probe would take 84 GWh, which is not super much (about 15 times more than a space shuttle launch), but of course the Starshot probes would be much lighter than this proposed telescope so it's not directly comparable.
If we assume the meter class telescope + power supplies and whatever else masses ~ 1 metric ton, it would take 1,853,298,442,530,598,439 Joules - 1.8 quintillion - 1.853 * 10^18 - to accelerate it to .2c. Only ~ 442 Megatons of TNT. Keep in mind, that is assuming 100% efficiency, which would be impossible with a light sail or any other known technology.
With all the various inefficiencies in power collection/generation, laser generation, momentum/power transfer, etc. we'd be talking probably somewhere around 5% end-to-end power transfer - if we were lucky. Which is still way better than the rocket equation (probably).
So to get the required 1.853 * 10^18 J at 5% efficiency, we'd need say 20x more power at earth to accelerate it (if 5% efficiency). So 3.706 * 10^19 J. Which starts get more concerning, at 8,840 gigatons of TNT.
Let's take the most efficient means we can imagine to produce energy, direct matter annihilation. Annihilating 1KG of mass (using 500g of Anti-matter, 500g of Matter) produces 8.986 * 10^16 J of energy. If we could somehow feed the resulting energy directly into the laser for accelerating the craft, and assume near 100% efficiency in doing so, before laser losses - we'd only need roughly 1000 KG of matter/anti-matter to do so.
Not bad!
But wait, our more likely end-to-end efficiency is at best 1%. Hmm. Which would require 100 times the input energy to spacecraft acceleration. 44 Gigatons of TNT or 1.853 * 10^20 J.
5KG of matter/antimatter.
Which is definitely not a significant fraction of earths mass, but yikes. I wouldn't want to pay that energy bill!
51,480,512,292,500 kWh (the 'wall plug equivalent') at my current rates would be $26 trillion dollars!
I haven't read the paper yet, but this thing would have to have a fair amount of nuclear power, and comms would be a challenge as well. As the abstract mentions, though, while the project has a high degree of difficulty, there appear to be no complete technology showstoppers to actually doing this, so it's at least as doable (and considerably cheaper than) a von Braun-style centrifugal space station in Earth orbit.
It'll be interesting to see if the idea gets any traction...