Submitted by darthatheos t3_10ve1np in space
moral_luck t1_j7hwh78 wrote
Reply to comment by [deleted] in Rolls-Royce Nuclear Engine Could Power Quick Trips to the Moon and Mars by darthatheos
Solar power is neither infinite in energy density, total amount of energy or duration of energy.
Not sure what you mean by "Solar is infinite."
[deleted] t1_j7hwnqn wrote
How many megajoules per kg is it?
moral_luck t1_j7i2c65 wrote
Einstein's most famous equation (E=mc^(2)) limits energy density of any fuel to 9 x 10^(10) MJ/kg
And that would be an antimatter reactor. Physics means no fuel can have infinite density.
[deleted] t1_j7i5cy1 wrote
Light. Zero mass. Lots of energy.
moral_luck t1_j7i7wee wrote
Where did the light come from?
SowingSalt t1_j7jjchk wrote
Therefore in the ratio mJ/kg, light is undefined and cannot be on the chart; which was the original point.
moral_luck t1_j7hz7ym wrote
Solar energy is hydrogen fusion, deuterium–tritium fusion is about 338,000,000 MJ/kg.
But we don't have the technology to create miniature suns in our rockets.
BTW, U-235 fission has an energy density of about 144,000,000 MJ/kg.
Another source puts the energy density of the sun's core around 6.43 x 10^(8) MJ/kg, or 643,000,000 MJ/kg.
The second source is titled The Source of Solar Energy.
[deleted] t1_j7i5md1 wrote
That's fusion reactors not solar energy on the surface of the earth
moral_luck t1_j7i7uhl wrote
Where does the solar energy on the surface of the earth come from?
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