4 ms·

Even if the "cost" of getting the required infrastructure into orbit (assuming Earth-based manufacturing) was close to zero, the energy requirements would still

by qayxc 5y ago

Even if the "cost" of getting the required infrastructure into orbit (assuming Earth-based manufacturing) was close to zero, the energy requirements would still eat up the benefits. SSP only works if every piece of the orbital infrastructure is sourced and built outside of Earth's gravity well. But that's not even the main concern with such system. The primary reason we won't see anything like this anytime soon is the simple fact that such system can easily be weaponised. An SSP is basically a potential space-based weapon. Even if there's no intention to use it as such, some governments are pretty much guaranteed to see it that way and proceed to install actual space-based weaponry in orbit.

BurningFrog 5y ago
> An SSP is basically a potential space-based weapon Asteroid mining has a similar problem. Any tech that can send a metal asteroid to Earth orbit can also smash it into Buenos Aires.
- nkrisc 5y ago
  It doesn’t even have to be intentional.
- iso1210 5y ago
  Any tech that can send a 1 ton roadster to mars can crash a 1 ton roadster into Buenos Aires at 20,000mph
  - wongarsu 5y ago
    Obviously. It all started as a way to drop bombs on London, and we are only now reaching a time where the majority of rocket models are not derivatives of ICBMs. Spaceflight is a story of a military technology finding civilian use. That has a very different ring to it than civilian technology being used as a weapon, even if the effect is similar.
  - foota 5y ago
    Wouldn't the car disintegrate in the atmosphere?
    - ac29 5y ago
      The car would obviously be a poor choice as a weapon. A big tungsten rod on the other hand... https://en.wikipedia.org/wiki/Kinetic_bombardment https://en.wikipedia.org/wiki/Kinetic_bombardment
  - Retric 5y ago
    Air resistance limits small kinetic kill weapons. Square cube law however means it’s less effective for larger objects.
    - iso1210 5y ago
      1 ton tungston rod wouldn't burn up.
      - Retric 5y ago
        A 1 ton rod would loose most of it’s kinetic energy on reintry. “A system described in the 2003 United States Air Force report[9] was that of 20-foot-long (6.1 m), 1-foot-diameter (0.30 m) tungsten rods that are satellite-controlled and have global strike capability, with impact speeds of Mach 10.“ That’s 1.725m2 of tungsten at 19,280kg/m2 = 33.2 metric tons and it’s still only doing Mach 10 on impact.
    - trhway 5y ago
      just make the large object split into many small kill weapons not far from the target(s).
  - kongin 5y ago
    A one ton roadster will burn up before it does anything, a large factory will not: >About once a year, an automobile-sized asteroid hits Earth's atmosphere, creates an impressive fireball, and burns up before reaching the surface. >Every 2,000 years or so, a meteoroid the size of a football field hits Earth and causes significant damage to the area. https://www.nasa.gov/mission_pages/asteroids/overview/fastfacts.html https://www.nasa.gov/mission_pages/asteroids/overview/fastfa...
  - labster 5y ago
    Think of the speeding ticket Elon will get.
skissane 5y ago
Maybe China will build such a system, not because it makes economic sense, rather for national prestige, so they can claim to be ahead of the US in that technology. Even if they spend a few billion for a modest sized demonstration system, that’s only a fraction of their national budget. How would the US respond? Possibly Congress will respond by paying to build its own bigger one, again not for the economics, simply for the prestige. I am not sure anyone will care that much about the “space-based weapon” angle. If it is a weapon, you just build your own and then you have one too, and now both sides have that weapon. The ability to have a (possibly illegal) space-based weapon yet publicly insist it is just a (completely legal) power generation demonstrator may even be attractive to military planners on both sides. However, in practice, a modest sized technology demonstrator may be quite limited in the damage it can inflict, unless it was enhanced with extra hardware that made it more obviously a weapon, and harming its plausible deniability.
- chii 5y ago
  There's no need for space based weapons when hypersonic missiles can deliver megatonne grade nuclear arsenals "easily" today. But framing it as a weapons system, to attract military funding (which ultimately ends up as useful civilian technology) isn't so bad.
formerly_proven 5y ago
Is it? Article claims 2 GW / 30 km², which is ~70 W/m², a fraction of solar irradiance in most places.
- ben_w 5y ago
  Sort of yes, sort of no. If there is at most one space based solar energy system visible from any given point on the ground, you can make strong safety claims based on wavelength and antenna size. However, if you limit yourself to one in any given sky, you necessarily either (1) put them in high orbit so they do useful things in local night, limiting you to a small total count planet-wide, or (2) put them in a low orbit, which means you can’t use them in local nighttime. If you want nighttime coverage and enough of these systems to be relevant to global power — and the current nameplate capacity of ground-based PV is just under a terawatt — you have to worry about multiple orbit-to-ground beams being directed at the same spot. While you could have up to about half a dozen giant ground-station for half a dozen giant beams, that needs ground level transmission over a significant fraction of the surface to be relevant to global energy needs, at which point you might as well make a planetary scale power grid and get your nighttime supplies from a mixture of the rooftops on the other side of the planet and some convenient deserts your energy supplier is renting.
  - T-A 5y ago
    > put them in high orbit so they do useful things in local night, limiting you to a small total count planet-wide Geostationary orbit is a circle over the equator with radius 42241 km, circumference 265408 km. Yes, it's "limited" in the sense that it's finite, but it's not exactly small. In its current primary use, communication satellites, there is a problem with interference; things like residential TV-sat dishes need to be small, so they have limited resolution, so those satellites need to be relatively far apart. That is not an issue for space based solar power. > put them in a low orbit [...] worry about multiple orbit-to-ground beams being directed at the same spot From different directions, at different times.
    - ben_w 5y ago

by qayxc 5y ago

BurningFrog 5y ago

> An SSP is basically a potential space-based weapon Asteroid mining has a similar problem. Any tech that can send a metal asteroid to Earth orbit can also smash it into Buenos Aires.

nkrisc 5y ago
It doesn’t even have to be intentional.
iso1210 5y ago
Any tech that can send a 1 ton roadster to mars can crash a 1 ton roadster into Buenos Aires at 20,000mph
- wongarsu 5y ago
  Obviously. It all started as a way to drop bombs on London, and we are only now reaching a time where the majority of rocket models are not derivatives of ICBMs. Spaceflight is a story of a military technology finding civilian use. That has a very different ring to it than civilian technology being used as a weapon, even if the effect is similar.
- foota 5y ago
  Wouldn't the car disintegrate in the atmosphere?
  - ac29 5y ago
    The car would obviously be a poor choice as a weapon. A big tungsten rod on the other hand... https://en.wikipedia.org/wiki/Kinetic_bombardment https://en.wikipedia.org/wiki/Kinetic_bombardment
- Retric 5y ago
  Air resistance limits small kinetic kill weapons. Square cube law however means it’s less effective for larger objects.
  - iso1210 5y ago
    1 ton tungston rod wouldn't burn up.
    - Retric 5y ago
      A 1 ton rod would loose most of it’s kinetic energy on reintry. “A system described in the 2003 United States Air Force report[9] was that of 20-foot-long (6.1 m), 1-foot-diameter (0.30 m) tungsten rods that are satellite-controlled and have global strike capability, with impact speeds of Mach 10.“ That’s 1.725m2 of tungsten at 19,280kg/m2 = 33.2 metric tons and it’s still only doing Mach 10 on impact.
  - trhway 5y ago
    just make the large object split into many small kill weapons not far from the target(s).
- kongin 5y ago
  A one ton roadster will burn up before it does anything, a large factory will not: >About once a year, an automobile-sized asteroid hits Earth's atmosphere, creates an impressive fireball, and burns up before reaching the surface. >Every 2,000 years or so, a meteoroid the size of a football field hits Earth and causes significant damage to the area. https://www.nasa.gov/mission_pages/asteroids/overview/fastfacts.html https://www.nasa.gov/mission_pages/asteroids/overview/fastfa...
- labster 5y ago
  Think of the speeding ticket Elon will get.

skissane 5y ago

Maybe China will build such a system, not because it makes economic sense, rather for national prestige, so they can claim to be ahead of the US in that technology. Even if they spend a few billion for a modest sized demonstration system, that’s only a fraction of their national budget. How would the US respond? Possibly Congress will respond by paying to build its own bigger one, again not for the economics, simply for the prestige. I am not sure anyone will care that much about the “space-based weapon” angle. If it is a weapon, you just build your own and then you have one too, and now both sides have that weapon. The ability to have a (possibly illegal) space-based weapon yet publicly insist it is just a (completely legal) power generation demonstrator may even be attractive to military planners on both sides. However, in practice, a modest sized technology demonstrator may be quite limited in the damage it can inflict, unless it was enhanced with extra hardware that made it more obviously a weapon, and harming its plausible deniability.

chii 5y ago
There's no need for space based weapons when hypersonic missiles can deliver megatonne grade nuclear arsenals "easily" today. But framing it as a weapons system, to attract military funding (which ultimately ends up as useful civilian technology) isn't so bad.

formerly_proven 5y ago

Is it? Article claims 2 GW / 30 km², which is ~70 W/m², a fraction of solar irradiance in most places.

ben_w 5y ago
Sort of yes, sort of no. If there is at most one space based solar energy system visible from any given point on the ground, you can make strong safety claims based on wavelength and antenna size. However, if you limit yourself to one in any given sky, you necessarily either (1) put them in high orbit so they do useful things in local night, limiting you to a small total count planet-wide, or (2) put them in a low orbit, which means you can’t use them in local nighttime. If you want nighttime coverage and enough of these systems to be relevant to global power — and the current nameplate capacity of ground-based PV is just under a terawatt — you have to worry about multiple orbit-to-ground beams being directed at the same spot. While you could have up to about half a dozen giant ground-station for half a dozen giant beams, that needs ground level transmission over a significant fraction of the surface to be relevant to global energy needs, at which point you might as well make a planetary scale power grid and get your nighttime supplies from a mixture of the rooftops on the other side of the planet and some convenient deserts your energy supplier is renting.
- T-A 5y ago
  > put them in high orbit so they do useful things in local night, limiting you to a small total count planet-wide Geostationary orbit is a circle over the equator with radius 42241 km, circumference 265408 km. Yes, it's "limited" in the sense that it's finite, but it's not exactly small. In its current primary use, communication satellites, there is a problem with interference; things like residential TV-sat dishes need to be small, so they have limited resolution, so those satellites need to be relatively far apart. That is not an issue for space based solar power. > put them in a low orbit [...] worry about multiple orbit-to-ground beams being directed at the same spot From different directions, at different times.
  - ben_w 5y ago