This is a super basic question, how do they prevent the panels from being hit my space debris or rocks, floaties etc?
Is it just that within its orbit there are next to no objects it could collide with, even small ones?
Starcloud
221–230 of 234 posts
Re: Starcloud
#222Last time these folks were mentioned on HN, there was a lot of skepticism that this is really possible to do. The issue is cooling: in space, you can't rely on convection or conduction to do passive cooling, so you can only radiate away heat. However, the radiator would need to be several kilometers big to provide enough cooling, and obviously launching such a large object into space would therefore eat up any cost s…
The Github paper seems to indicate they have considered the thermal aspects fairly heavily and mention that "conduction and convection to the environment are not
available in space".
Re: Starcloud
#223Last time these folks were mentioned on HN, there was a lot of skepticism that this is really possible to do. The issue is cooling: in space, you can't rely on convection or conduction to do passive cooling, so you can only radiate away heat. However, the radiator would need to be several kilometers big to provide enough cooling, and obviously launching such a large object into space would therefore eat up any cost s…
Maybe this is reductive, but there are times that I'm concerned the only thing keeping me from getting gobs and gobs of startup funds are the facts that I understand basic principles of engineering in space. I could be wrong and this will be a slam dunk. To me, however, the costs/complexity (Cooling, SRP perturbation, stationkeeping, rendezvous, etc.) far outweigh the benefits of the Cheap as Free (tm) solar power
Reading the paper they wrote on this from their GitHub site, it does take into account the thermal management aspects quite considerably.
https://starcloudinc.github.io/wp.pdf
Your thinking seems more risk averse, which is similar to myself. However that doesn't mean that without the business drivers these types of things can't happen if enough attention is given too it. Costs are often because we're comparing one thing which has significant efficiencies built into the supply chain, vs something that doesn't, which by virtue drives up the cost. Perhaps Nvidia have money to burn on trying something.
Re: Starcloud
#224Last time these folks were mentioned on HN, there was a lot of skepticism that this is really possible to do. The issue is cooling: in space, you can't rely on convection or conduction to do passive cooling, so you can only radiate away heat. However, the radiator would need to be several kilometers big to provide enough cooling, and obviously launching such a large object into space would therefore eat up any cost s…
This is a big thing never shown in sci-fi. For example, those huge torch ships in The Expanse would need gigantic radiators. Even if the drive were upwards of 90% efficient the waste heat would melt the engine and the rest of the ship. Even the ISS has sizable radiators. The Shuttle had deployable radiators in the form of the bay doors if my memory serves me correctly. Oddly enough the otherwise dumb Avatar films are…
The book Saturn Run has an interesting design utilized for a spaceship.
Re: Starcloud
#225Re: Starcloud
#226Earlier quoted context omitted.
Maybe this is reductive, but there are times that I'm concerned the only thing keeping me from getting gobs and gobs of startup funds are the facts that I understand basic principles of engineering in space. I could be wrong and this will be a slam dunk. To me, however, the costs/complexity (Cooling, SRP perturbation, stationkeeping, rendezvous, etc.) far outweigh the benefits of the Cheap as Free (tm) solar power
Assuming these people don't understand that their ideas are unworkable is a mistake. Don't believe for a second they are stupid or ignorant. The difference between a criminal and a law-abiding citizen isn't that the citizen knows that crimes are wrong, it's that the citizen cares that crimes are wrong and the criminal doesn't.
>they are stupid or ignorant.
Nope, probably the more apt description is 'in denial'.
Re: Starcloud
#227[deleted]
Re: Starcloud
#228Re: Starcloud
#229Earlier quoted context omitted.
Extremely rough one significant digit analysis from first principles, containing a lot of assumptions: For solar panels: Assuming area of 1000 square meters (30m x 30m square), solar irradiance of 1 kW/m^2, efficiency of 0.2. As a result power is 200 kW. For radiators: Stefan-Boltzmann constant 6E-8, temperature difference of 300 K, emissivity of one, we get total radiator power 1000 x 6E-8 x 300^4 = 486 kW. The radi…
There's a very clever scheme I remember reading about a while ago where you dump the heat into an oil that you then spray in a fine mist towards a collector. You get a collosal surface area that way, in a very confined volume, with not that much more mass than a coolant fluid which you already need; and it's relatively easy to homogenise the temperature across the radiating particles. I seem to recall that it got as…
In space this wouldn't really work since there's no conduction or convection.
If you think of a big ball of droplet mist. From the point of view of a droplet in the center, it gets heat radiation from all the droplets around it. It can only radiate heat to black sky it sees, and it might be none, it's "sky" is just filled by other hot droplets. So it doesn't cool at all.
The total power radiated can't exceed the proportion to the macro surface area with tricks.
Re: Starcloud
#230Earlier quoted context omitted.
It really depends where they get the water. If they're pumping an aquifer fry and doing evaporative cooling they could be just boiling an entire areas water source. If they could figure out how to use salt water it'd be ideal.
Just run your closed loop cooling through a heat exchanger in sea water. They probably do something like this already.
I think they prefer to use evaporative cooling though.