> I think fusion power is a useful thing to research though, in case the sky goes dark one day.

"Someone started a war, and no one knows who, but it was known that it was mankind who blotted out the sky, attempting to deprive the machines of the solar power they required to function."

or perhaps: Johann Johannsson - Sun's Gone Dim (https://www.youtube.com/watch?v=Iv4CuIIspdE)

Moreover (and more seriously), though, fusion could be incredibly useful in terms of rocketry and power generation further out in the solar system.