[zaarn]

Solar light isn't that strong once you go beyond mars.

Earth gets 1400 W/m^2, at Saturn only 16 W/m^2 and on Neptune maybe 1.5 W if you get lucky.

60 days of continous harvesting, assuming the spacecraft doesn't use any power (which is not true in reality), is about 2 kWh at Neptune. Not that much. Saturn would be 23 kWh.

[aetherspawn]

Yuck, that’s miserable.

[zaarn]

It's the inverse square law that bites you here as the same amount of energy gets stretched out into a larger sphere as it travels outwards (at earth the energy is 1.4kW for a square meter, when going outwards, this square meter gets stretched)

Double the distance and you get 1/4th the energy.

Saturn is 9AU or 9 times as far as earth; 1/81th the energy. (1400 / 9^2 = 17, so math checks out; roughly)

We're quite lucky to be close enough for solar energy to be a viable source of energy.

[*]: https://en.wikipedia.org/wiki/Inverse-square_law

[blattimwind]

> We're quite lucky to be close enough for solar energy to be a viable source of energy.

If solar energy were not viable, this form would not exist.

[basementcat]

If solar energy were not viable, Hacker News posts might be written by technologically inclined chemoautotrophs hacking in the basement of their hydrothermal vent. https://en.wikipedia.org/wiki/Chemosynthesis

[zaarn]

Just because solar cells don't work doesn't mean photosynthesis wouldn't work.