The project estimates are completely off. Building a 1gigawatt power plant costs 10billion. Let alone building 100 of them. Also making the laser array. Also you can't have reflection without absorption. Also we don't have solar sails that fit the bill. This project is barely physically and economically plausible. Its not a question of scaling, or engineering. The physics just don't work. We have a way to get a space…
100 GW over 2 minutes is 3 1/3 GWh, or the equivalent of 37037 Tesla Model S 90 kWh batteries, or about $500M in batteries (in 2016).
Agreed on the extreme skepticism warranted. I am imagining these "solar sails" to be essentially spherical, both for structural reasons and so that their response to applied laser power does not depend on orientation. The electronics in precision guided mortars in the US army survive 50,000g. http://proceedings.ndia.org/C347/Davis.pdf (This is only for the fraction of a second when they are fired, and I don't know ho…
> The electronics in precision guided mortars in the US army survive 50,000g And then are immediately 'disposed of'. That is, quite literally, a fire-and-forget problem; those electronics don't have to keep working for months or years.
Yes but they do have to keep working after those 50,000G. Which is the thing: provided they survive acceleration, the remaining problem is cosmic rays. But we're talking about such small craft here that we'll be able to launch literally hundreds, probably thousands - the real challenge is getting the 100GW laser array built. Once you have it...no reason not to use it.
>Worst case, we'll learn something we might learn something, but we have to use resources for studying and there might just be better and/or more useful alternatives
Side effects of these projects, even if they fail, may be massively valuable. Sometimes solving problem X that isn't a big concern for society will solve problem Y down the track. History of maths is littered with things that were useless when they where first invented, such as imaginary numbers.
I'm still not arguing that and I'm as excited as everyone else when someone comes with a bold idea as this, still, you can't gouge how well the money will be spent and downplaying risks and alternatives of undertaking a multi decade project because we are in the heat of the moment is not wise. Science justice warriors should take a deep breath before pointing fingers imo. We are inherently in a box and I doubt anyone can imagine what technology will look like in 10 years, let alone 40.
The project estimates are completely off. Building a 1gigawatt power plant costs 10billion. Let alone building 100 of them. Also making the laser array. Also you can't have reflection without absorption. Also we don't have solar sails that fit the bill. This project is barely physically and economically plausible. Its not a question of scaling, or engineering. The physics just don't work. We have a way to get a space…
Do you seriously think these guys haven't heard of Project Orion or wouldn't use Orion's approach if they thought it was best? In case you didn't notice, Freeman Dyson is involved with Starshot.
People have to learn how to harvest power from fusion before.
You know how they have chemically pumped lasers? So it would be awesome to directly pump the laser from H3 fusion. H3 fusion is actually very easy - I think we could do it today. We just don't have a readily available source of H3 for fuel.
3He fusion is easy—you can do it in a garage with some hacked-together equipment.
However, 3He fusion with net power output is exceptionally hard, even with complete disregard to cost. Much harder than deuterium-tritium fusion. We don't know how to do it yet.
I also am skeptical. Why not instead try to send a probe into the interior of the sun? (because its cooler there than at the point of those lasers) Why not create a survey of the Oort cloud (because its an order of magnitude closer). This project seems cool; but maybe not well thought out.
These people are obviously very passionate about their project, and they're moving forward on something they want to do. If you're so passionate about those projects you mentioned, start making them happen! Don't sit around complaining about people who are "doing" stuff because they're not doing the stuff you want them to be doing. Get out there and do the stuff yourself!
Good attitude! Still, it doesn't make their project any more likely to succeed. Those others I mentioned - easier by an order of magnitude. It makes them sound insincere.
Yep. "Use a material with better than 99.999% reflectivity. Usually, highly reflective surfaces are dielectric mirrors, which are composed of ‘sandwiches’ of material, with each layer reflecting back a modest fraction of the total. Each layer needs to be at least a quarter of a wavelength thick. The weight can be reduced by using a monolayer with high reflectivity at the correct wavelength. Based on recent research,…
So it sounds like we'd have a layered sequence of dialectric mirrors (themselves many layers each) each reflecting a different wavelength. The first layer lasts until the laser redshifts out of that layer's efficient reflection range, then vaporizes revealing the next layer tuned to the redshifted laser. That layer lasts until the laser redshifts even further, then vaporizes to reveal the next, and so on. Sacrificial…
Some types of lasers (e.g. free electron lasers) can be tuned to arbitrary wavelengths, so you could maybe adjust the frequency of the laser as the craft accelerates.
You know how they have chemically pumped lasers? So it would be awesome to directly pump the laser from H3 fusion. H3 fusion is actually very easy - I think we could do it today. We just don't have a readily available source of H3 for fuel.
3He fusion is easy—you can do it in a garage with some hacked-together equipment. However, 3He fusion with net power output is exceptionally hard, even with complete disregard to cost. Much harder than deuterium-tritium fusion. We don't know how to do it yet.
Thanks for the correction. Seems the rosy predictions I remembered are not accurate.
Even if this is possible, it'll probably be prohibitively expensive to do constant resupplies when you won't know for years if previous trips have worked. A manned mission or a resupply mission would also be orders of magnitude beyond the masses they're talking about, which strains credibility even further.
I am pretty sure you just sent out a new boat of supplies every year make it or not. Worse case the mission fails and the next mission has 20 supply ships in orbit waiting for them. I have no idea on the minimum mass required to send supplies, i.e. if you can recycle 99% of the water you need, would only need a few drops per day. If you can only recycle 50%, you are going to need a bunch.
Nah - they're already pushing some theoretical limits by talking about planetary levels of energy. You're talking about just throwing money at doing that many times in a row with no proof of success.