No, I wasn't referring to ATK's brochure but to actual Mars surface architecture trades which include wind load masses, etc.Here is a group of slides gathered by fission /advocates/ showing that solar is comparable or better that nuclear (for Equatorial sites), slide 33: http://spirit.as.utexas.edu/%7Efiso/telecon/Rucker_12-7-16/Rucker_12-7-16.pdfI believe a mix of power makes the most sense, just like on Earth. But I don't see where Mueller is getting this idea that solar is heavier unless you're proposing a much more radical nuclear reactor design as I mentioned up thread (or tap an aquifer and dump heat into the aquifer).Also, Kilopower units are $70-80 million apiece. SpaceX can't afford that price even for a single ITS worth of power.
No, I wasn't referring to ATK's brochure but to actual Mars surface architecture trades which include wind load masses, etc.Here is a group of slides gathered by fission /advocates/ showing that solar is comparable or better that nuclear (for Equatorial sites), slide 33: http://spirit.as.utexas.edu/%7Efiso/telecon/Rucker_12-7-16/Rucker_12-7-16.pdfI believe a mix of power makes the most sense, just like on Earth. But I don't see where Mueller is getting this idea that solar is heavier unless you're proposing a much more radical nuclear reactor design as I mentioned up thread (or tap an aquifer and dump heat into the aquifer).Also, Kilopower units are $70-80 million apiece. SpaceX can't afford that price even for a single ITS worth of power. (This is a good opportunity for collaboration with folks like NASA, by the way... NASA or some international partner contributes some reactors to provide more robustness and diversity to the fledgling settlement's power grid).
Kilopower is the only realistic nuclear power source in the near term. As Mueller said, SpaceX is not going to develop nuclear power, they can't afford it. But NASA can (partly because they can partner with DOE who has access to "free" enriched uranium).Thin film is not irrelevant, as very lightweight structures are possible (yes, compatible with wind loads), and making structure for the thin film arrays is one of the most straightforward structural ISRU things you could do... Compressed soil bricks is one such method (that we know Musk is looking into for other purposes).
QuoteBefore the storm hit, Phoenix was generating about 2,100 Watt-hours each sol... (From news stories at the time). You can compare that to the insolation graph data I posted upthread.Also, in practice:The system was down after a few months. It was ice, but it would also have gone done due to excessive wind, or wind-induced fatigue over time, etc. It takes an inordinate amount of effort to make a PV panels that survives the environment for years, and until you do, you don't have an "almost system", you simply don't have a system.
Before the storm hit, Phoenix was generating about 2,100 Watt-hours each sol...
what are you talking about as far as insolation values? All I did was link to the study in the FISO presentation.
The previous study I pointed to assumed tracking for solar because it both increased output nominally and helped solve the dust and wind problem (by tilting to aid dust removal and by feathering in order to minimize wind loading). It's really a no-brainer (and even if it gets stuck, it still produces power, unlike if the moving parts of a reactor gets stuck).
Quote from: Robotbeat on 05/22/2017 12:04 amThe previous study I pointed to assumed tracking for solar because it both increased output nominally and helped solve the dust and wind problem (by tilting to aid dust removal and by feathering in order to minimize wind loading). It's really a no-brainer (and even if it gets stuck, it still produces power, unlike if the moving parts of a reactor gets stuck).That's fine. Then the design should include the benefits of tracking in terms of power output (~30% more), but also the mass penalty since the panels need to be supported on a central torque tube with the ability to pivot. (Or on a gimbal if you're doing 2 axis tracking).
As for cleanliness, there are 100 designs for cleaning systems. It's just a function of weight. You can have robots run along the panels, for example, using the edges as rails. It's just that your panels now have to be sturdy enough for that.
With solar, everything is possible. It's just the resultant kg/kWatt that ends up being high.
The bottom line is that average surface insolation is 60-80 W/m2. (Averaged over night/day and over the year), or ~100 in the most favorable location/ time-of-yearOn top of that you have conversion efficiency (panels are 30-40% efficient, but are probably not tracking, and probably are partially obscured by dirt) and you realize you're scavenging power here.I quoted above that Phoenix's panels got 87 Watts-avg out of 3.1 m2 of receiver, or 28 W-avg/m2, when relatively clean.This is in rough agreement with the paper.Long term solar deployment will do worse. There will be more dust, more need to clean, more degradation, etc.If you want a MWatt of power for ISRU, you need 35,000 m2 of installed PV area. (7 football fields).Just for 1 MWatt.
In space power generation is one of the things NASA should be funding as a nuclear reactor makes a dust storm go from something that would shut down normal operations and possibly force an evacuation to more of a nuisance.
It still remains a very big structure to erect and to keep clean.
Quote from: john smith 19 on 05/22/2017 06:52 amIt still remains a very big structure to erect and to keep clean. I've already proposed a possible solution before: slighly tilted panels with an electroacoustic transducer attached to the surface (or support beams), to make it vibrate. Should be enough to kick out the dust on the low g of Mars.
Quote from: IRobot on 05/22/2017 01:28 pmQuote from: john smith 19 on 05/22/2017 06:52 amIt still remains a very big structure to erect and to keep clean. I've already proposed a possible solution before: slighly tilted panels with an electroacoustic transducer attached to the surface (or support beams), to make it vibrate. Should be enough to kick out the dust on the low g of Mars.So for that to even have a chance to work, the panels have to be rigid.
So 5 kg/m2, before the railing and acoustic generators... Now add the support structure, and you're at 7-8 kg/m2.Now add cabling to cover the several football fields, batteries for winter night time, and you see the problem.
Now add cabling to cover the several football fields, batteries for winter night time, and you see the problem.
Quote from: meekGee on 05/22/2017 01:43 pmNow add cabling to cover the several football fields, batteries for winter night time, and you see the problem.No need to do it at night. The devices can be fed from the panel. They can do regular shakes or be activated by wireless control. No need for a lot of cabling.
Power cabling, for the field... And general usage batteries, sized to work even in winter when days are short - just adding to the mass of the system.