4 ms·

How much damage would air do to satellites at that altitude? The 2nd largest component is atomic oxygen, which doesn't sound friendly. edit: From fig. 3, compa

How much damage would air do to satellites at that altitude? The 2nd largest component is atomic oxygen, which doesn't sound friendly. edit: From fig. 3, compared against [0], the atomic oxygen density for this concept is 10²-10³ greater than at ISS' altitude (which considers it a hazard [1]). /edit: [2] has photos of ISS O damage [0] http://esmat.esa.int/publications/published_papers/corrosion_in_space.pdf http://esmat.esa.int/publications/published_papers/corrosion... ("...oxygen atoms have a density of 10⁷ to 10⁸ atoms/cm³ at International Space Station (ISS) altitude (around 400 km) with a thermal energy of approx. 0.1 eV") [1] https://ntrs.nasa.gov/api/citations/20010038448/downloads/20010038448.pdf https://ntrs.nasa.gov/api/citations/20010038448/downloads/20... [2] https://ntrs.nasa.gov/api/citations/20190025445/downloads/20190025445.pdf https://ntrs.nasa.gov/api/citations/20190025445/downloads/20... ("Figure 3.—Atomic oxygen undercutting degradation of the P6 Truss solar array wing blanket box cover on the ISS after only 1 year of space exposure.")

wongarsu 5y ago
With that low an orbit you need hundreds of satellites to get decent line-of-sight coverage of the earth. I'd expect most satellites that go there are "mass produced" for that reason alone and are happy with a lifetime that's about 10 times less than that of the ISS, and a safety factor that's much lower.
- ncmncm 5y ago
  We might imagine ceramic passivation coatings to protect surfaces of extra-low-orbiting birds. The ability to collect enough energy to drive thrust from large, draggy solar panels seems like a limiting factor. Maybe they could double as wings? Keeping them oriented to minimize drag would interfere with their ability to collect energy. It might be the optimal geometry for such a bird would be a hollow cylinder with panels ranged all the way around the outer surface.
  - sitkack 5y ago
    Beam energy from a higher orbit, microwave or optical. They could also have highly eccentric orbits so that they are only low over the coverage area.
    - ncmncm 5y ago
      Or laser from the ground.
tomrod 5y ago
I wonder if plastic components work for that use case?

wongarsu 5y ago

With that low an orbit you need hundreds of satellites to get decent line-of-sight coverage of the earth. I'd expect most satellites that go there are "mass produced" for that reason alone and are happy with a lifetime that's about 10 times less than that of the ISS, and a safety factor that's much lower.

ncmncm 5y ago
We might imagine ceramic passivation coatings to protect surfaces of extra-low-orbiting birds. The ability to collect enough energy to drive thrust from large, draggy solar panels seems like a limiting factor. Maybe they could double as wings? Keeping them oriented to minimize drag would interfere with their ability to collect energy. It might be the optimal geometry for such a bird would be a hollow cylinder with panels ranged all the way around the outer surface.
- sitkack 5y ago
  Beam energy from a higher orbit, microwave or optical. They could also have highly eccentric orbits so that they are only low over the coverage area.
  - ncmncm 5y ago
    Or laser from the ground.

tomrod 5y ago

I wonder if plastic components work for that use case?