3 ms·

You don't get heat conduction and convection in space, but thermal radiation works.

• dredmorbius 6y ago
  At the rate of about 100--350 W/m². More energy -> more radiators. At about 12 kg/m^2 launch budget * $10k/kg LEO. https://en.wikipedia.org/wiki/Spacecraft_thermal_control#Radiators https://en.wikipedia.org/wiki/Spacecraft_thermal_control#Rad... The ISS has 156 m² of radiators, compared with 3,246 m² of solar PV arrays.
  • marcinzm 6y ago
    >More energy -> more radiators. Which you can make out of the asteroids you're mining for the cost of shipping up the production facilities. It's a bootstrap cost problem rather than a fundamental efficiencies problem. >$10k/kg LEO. $2.5k last I heard with the Falcon 9 and SpaceX is aiming to go much lower. edit: And by much lower Musk means $10/kg to lunar orbit (that's dollars not thousands of dollars). Even if he's off by an order or two of magnitude it's still a lot cheaper.
    • dredmorbius 6y ago
      Launch costs are falling, though (and despite being proved wrong several times by Musk) $10/kg Lunar sounds delusional. Consider that typical bulk freight costs on Earth are in the range of $0.40/tonne-day (180,000 DWT Capesize vessel at $48,000/day https://www.easyship.com/blog/bulk-shipping-for-delivery https://www.easyship.com/blog/bulk-shipping-for-delivery), or roughly $5/tonne for a 14 day transoceanic voyage (8,000 mi, 12,000 km, very roughly). Only twice that to Lunar surface is ... dubious. In situ construction is an option, and while asteroids can be metal-rich, useful in fabricating condenser and evaporator coils, they tend to be refrigerant poor. Substances which have properties of good refrigerants (boiling and volatility at low pressures and temperatures) are poorly retained by microgravity bodies in vacuum.