Artist's concept of a Fission Surface Power system on the Moon.
Credit: NASA
It's an ambitious plan of NASA's to return astronauts to the Moon by 2020 and set up a lunar outpost.
Just one of the many challenges their engineers face is finding a way to power this most remote manned beacon of human civilisation with nothing to burn, little sunlight, no running water and no wind.
One solution, though, could be nuclear power.
Fission Surface Power (FSP) is one of the more interesting options NASA is considering. If this method is chosen, an engine invented in the early 1800s by Scottish brothers Robert and James Stirling could help make it work.
Over the years the Stirling engine has earned a sterling reputation here on Earth, and it may one day prove its worth on the Moon.
"Inhabitants of a lunar outpost will need a safe and effective way to generate light and heat and electricity," says Mike Houts of NASA's Marshall Space Flight Centre. "The tried and true Stirling engine fits the bill. It's not only reliable and efficient, but also versatile and clean."
NASA is partnering with the U.S. Department of Energy to develop Fission Surface Power technology to produce heat and feed it into a Stirling engine, which, in turn, would convert heat energy into electricity for use by Moon explorers.
It's not certain that NASA will adopt this kind of power system, but it does have some very appealing qualities, says Houts.
"A key advantage to this power system is that it wouldn't need sunlight to operate. An FSP system could be used to provide power any time, any place, on the surface of Moon or Mars.
"It could be used at the poles and away from the poles, it could weather a cold lunar night, and it would do well in places like deep craters that are always shaded. Not even a swirling, sunlight-obscuring Martian dust storm could stop it," he says.
NASA's engine would only need to produce 40 kW or less power – just enough for a lunar outpost.
"This power level is high by space standards but extremely low by Earthly standards," says Houts. "It's about one 20,000th of what a typical Earthly reactor puts out. We'd only need a tiny reactor on the Moon – the fuelled portion would be only about 10 inches [25 cm] wide by 1.5 feet [46 cm] long."
It would provide more power with less mass than other power systems. The whole assembly – radiator on top of Stirling engine on top of reactor – could be stowed in a fraction of the lunar lander.
Solar on the moon? Please!
Solar on the moon? Please! On most of the moons surface there is roughly 2 weeks of light followed by 2 weeks of dark. Solar & batteries, at the moment, are just not up to the task!