NASA enlisted the aid of researchers at the University of Florida to reduce the weight of spacecraft leaving Earth.
They came up with a way to make rocket fuel from human waste (especially poop).
Enough to power the return flight, saving on carting all that fuel into space.
An added bonus was not having to carry all that waste back to Earth where it’s usually burned up during re-entry.
Researchers found an anerobic digester process that could produce 290 liters of methane per crew per day, all from human waste.
This must be useful here on Earth. Methinks high-rise buildings with lots of residents producing waste would be an ideal research project.