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>Those fit on satellites in zero g. The moon has gravity so you support them at an angle you need bracing on something else UltraFlex/MegaFlex is rated for 3g

by jhgb 5y ago

>Those fit on satellites in zero g. The moon has gravity so you support them at an angle you need bracing on something else UltraFlex/MegaFlex is rated for 3g acceleration on those satellites even when fanned out, why do you think it would have problems with 0.16g? That's one twentieth of what they're supposed to withstand. >but that doesn’t work on the moon as it hits 260 degrees Fahrenheit in the day That's just not the case on the Lunar south pole: https://agupubs.onlinelibrary.wiley.com/cms/asset/60707425-279b-4609-b8e2-307165678391/jgre20604-fig-0011-m.jpg https://agupubs.onlinelibrary.wiley.com/cms/asset/60707425-2... > Further you need cables from wherever they are to where up your using power. High-voltage cables are not that heavy. > Sure, and that worked wonderfully a lab. But, production systems need to worry about a great deal of stuff that doesn’t apply in a lab setting. I don’t mean this dismissively yes I completely agree in theory it could work, but it’s just not working technology yet. Of course you don't; you're just disingenuously moving the goalposts.

Retric 5y ago
> why do you think it would have problems with 0.16g? That's one twentieth of what they're supposed to withstand. You seem to be stuck on just one issue, heat is vastly more of an issue than this. Anyway, flexing isn’t breaking. https://www.americaspace.com/wp-content/uploads/2012/04/LIFE-Phoenix-on-Mars.jpg https://www.americaspace.com/wp-content/uploads/2012/04/LIFE... The actual panel on Mars isn’t flat or particularly big. Now, if we’re assuming the Moon mission is going to be at it’s equator then laying them directly on the lunar surface is fine. But big arrays at an angle need to be rigid or you’re losing poster from a using a worse angle due to the curve, either option means more weight for a given power output. > That's just not the case on the Lunar south pole Sure, and that deals with heat but now the solar array needs to deal with being at the poles.
- jhgb 5y ago
  This is an absolutely meaningless level of deformation. The array will be perfectly fine in Lunar gravity. And even if it weren't, instead of a fan, you could equally well shape it into a folded vertical curtain hanging from a beam with pretty much the same parameters. > Sure, and that deals with heat but now the solar array needs to deal with being at the poles. "Now"? It needed to deal with being at the pole the whole time. There was never an intention to put it elsewhere.
  - Retric 5y ago
    > you could equally shape it into a folded vertical curtain from a beam with pretty much the same parameters. Attaching a beam at one end requires a more rigid structure which is more weight, which is exactly what I said the problem was several times. > There never was an intention to put it elsewhere. I just said you could lower weight by laying them flat at the equator. My point was simply that isn’t an option, therefore you they need extra support. Operating closer to the poles has both clear advantages and downsides, access to water is a big benefit but it’s not quite as obvious a choice as often assumed.
    - jhgb 5y ago
      > Attaching a beam at one end requires a more rigid structure which is more weight Not really because that allows you to omit other parts of the original self-supporting "fanned" structure which formerly had a similar role to that beam. Furthermore you wouldn't be building this structure to withstand 3g like the "stock" UltraFlex/MegaFlex arrays but you'd build it specifically to withstand static 0.16g in one axis for deploying after landing on the Moon. Consequently I very strongly doubt that this would give it "more weight" than the current UltraFlex/MegaFlex arrays already have because you're assuming more weight for a flimsier structure and that just doesn't make any sense, unless you'd assume the use of inferior materials for some reason.
      - Retric 5y ago
        That fanned structure is very strong. For a one dimensional example consider an I-beam supported at the center vs having that same I-beam attached only at the edge. Which do you think can support more weight? And again even at Mars’s 0.38g it’s already bending. It can clearly survive more force, but not at an optional solar collection angle. Use the same thing on the moon near the poles and sure it’s not going to break, but it’s also not collecting 200W/kg.

by jhgb 5y ago

Retric 5y ago

> why do you think it would have problems with 0.16g? That's one twentieth of what they're supposed to withstand. You seem to be stuck on just one issue, heat is vastly more of an issue than this. Anyway, flexing isn’t breaking. https://www.americaspace.com/wp-content/uploads/2012/04/LIFE-Phoenix-on-Mars.jpg https://www.americaspace.com/wp-content/uploads/2012/04/LIFE... The actual panel on Mars isn’t flat or particularly big. Now, if we’re assuming the Moon mission is going to be at it’s equator then laying them directly on the lunar surface is fine. But big arrays at an angle need to be rigid or you’re losing poster from a using a worse angle due to the curve, either option means more weight for a given power output. > That's just not the case on the Lunar south pole Sure, and that deals with heat but now the solar array needs to deal with being at the poles.

jhgb 5y ago
This is an absolutely meaningless level of deformation. The array will be perfectly fine in Lunar gravity. And even if it weren't, instead of a fan, you could equally well shape it into a folded vertical curtain hanging from a beam with pretty much the same parameters. > Sure, and that deals with heat but now the solar array needs to deal with being at the poles. "Now"? It needed to deal with being at the pole the whole time. There was never an intention to put it elsewhere.
- Retric 5y ago
  > you could equally shape it into a folded vertical curtain from a beam with pretty much the same parameters. Attaching a beam at one end requires a more rigid structure which is more weight, which is exactly what I said the problem was several times. > There never was an intention to put it elsewhere. I just said you could lower weight by laying them flat at the equator. My point was simply that isn’t an option, therefore you they need extra support. Operating closer to the poles has both clear advantages and downsides, access to water is a big benefit but it’s not quite as obvious a choice as often assumed.
  - jhgb 5y ago
    > Attaching a beam at one end requires a more rigid structure which is more weight Not really because that allows you to omit other parts of the original self-supporting "fanned" structure which formerly had a similar role to that beam. Furthermore you wouldn't be building this structure to withstand 3g like the "stock" UltraFlex/MegaFlex arrays but you'd build it specifically to withstand static 0.16g in one axis for deploying after landing on the Moon. Consequently I very strongly doubt that this would give it "more weight" than the current UltraFlex/MegaFlex arrays already have because you're assuming more weight for a flimsier structure and that just doesn't make any sense, unless you'd assume the use of inferior materials for some reason.
    - Retric 5y ago
      That fanned structure is very strong. For a one dimensional example consider an I-beam supported at the center vs having that same I-beam attached only at the edge. Which do you think can support more weight? And again even at Mars’s 0.38g it’s already bending. It can clearly survive more force, but not at an optional solar collection angle. Use the same thing on the moon near the poles and sure it’s not going to break, but it’s also not collecting 200W/kg.