Strange that the article would say that when, in point of fact, the US is also working plans for lunar nuclear power. It's really the only sensible way to power a moon base with current technology, so anyone who is considering one is working designs for a nuclear power plant.
How do you cool a nuclear reactor on the moon?
The ground would probably work fine as a heat sink.
It's already pretty cold
The big problem with space is overheating. Space may be cold but there is no way to get rid of that heat except for radiators. Convection doesn’t exist in a vacuum.
Right, but conduction does work on the moon. You have the ground as a giant heatsink. While the surface does get pretty hot in daylight, I am guessing that heat doesn't go very deep so you could probably bury your cooling lines.
It just requires humans up there to dig and bury the cooling lines.
Probably a stupid question but how can it be cold if there's no heat transfer?
it's kindof neither.
Our normal sense of hot/cold is a measure of how hot the particles around us are. Space has so few particles, that whole paradigm breaks down.
Technically space is hot since temperature is a function of average particle movement and spaceborne particles are mostly moving stupid fast. Fortunately there are very few particles in any given volume of “empty” space so that translates to space being “cold”.
Only at night.
The lunar exosphere is too skimpy to trap or spread the Sun's energy, so differences between sunlit and shadowed areas on the Moon are extreme. Temperatures near the Moon's equator can spike to 250°F (121°C) in daylight, then plummet after nightfall to -208°F (-133°C).
Which sounds like a pretty big challenge for a nuclear reactor. Maybe they only plan to put them on the poles?
Go Thorium MSR and bury it underground and you don't really have to worry about it. Might need some modification for moon gravity but otherwise seems like the best bet.
That was my first thought, but then my second thought was even more terrifying - how do you protect your nuclear power facility from celestial impacts? The moon must get pelted with thousands of little bits of space debris every day considering it has no atmosphere. All it would take is a basketball-sized meteorite to slam into the reactor chamber and possibly cause a meltdown.
Cover it with a ton of moon soil
We'll take a second moon, cut it in half, and use it as a shield for the first moon
That's a challenge that people are working on for sure. Likely some kind of radiant cooling, but it's a lot of heat.
Heat also dissipates via radiation, not just conduction. I would imagine that nuclear power on the moon won’t involve hauling a lot of liquid coolant/heat exchanger/energy transfer because liquids are wicked heavy, hauling that up to orbit and then landing it is gonna take a lot of energy. They do acknowledge that cooling is an issue they’re working on.
Maybe some kind of RTG? I couldn’t find an article that said what the NASA contractors chose to build.
No, RTGs just don't generate the kind of power you'd need. I mean, they're awesome for generating electricity for a long time, but just not a lot of it. No, these are fission plants.
Is solar power combined with battery storage not an option?
Not really. Current battery technology is to put it lightly not the type of thing you want to rely on for long term life support. Lithium ion the current go to for rechargeable batteries physically degrades as you charge it. One of the main things you can do to reduce this is don't fully charge the battery. For example if the battery degradation from 0%* to 100%** is a cycle then 50% to 80% is only 21% of a cycle. That'll extend the lifetime of the battery (not the capacity) by about 5 times! That's pretty significant but you lose out on 20% of the batteries capacity permanently, even as the capacity decreases from degradation.
You've probably seen the hype about Sodium batteries which are currently 50% less energy dense which just immediately means NOPE for use in space.
* Lithium ion batteries are extremely difficult to actually fully discharge (controller won't let you)
**Lithium ion batteries should never be fully charged it causes them excessive damage so the controller prevents this from happening
They do it on the ISS though?
Although Li-Ion batteries typically have shorter lifetimes than Ni-H2 batteries as they cannot sustain as many charge/discharge cycles before suffering notable degradation, the ISS Li-Ion batteries have been designed for 60,000 cycles and ten years of lifetime, much longer than the original Ni-H2 batteries' design life span of 6.5 years.
ISS doesn’t have a two week long Lunar Night where solar panels dont work
The eternal light idea is fascinating but even in the best case scenarios, you’d need batteries to supply all power for two full days. In the more prudent case since lives depend on it, you’d need significantly more to cover any outages
Meanwhile, 2-3 nuclear reactors strung out on different sides and with redundant connections, and you’re good for 20 years and many types of outages
Much less power for the weight, and weight is the big deal when you're sending things from earth.
Strange that the article would say that when, in point of fact, the US is also working plans for lunar nuclear power. It's really the only sensible way to power a moon base with current technology, so anyone who is considering one is working designs for a nuclear power plant.
How do you cool a nuclear reactor on the moon?
The ground would probably work fine as a heat sink.
It's already pretty cold
The big problem with space is overheating. Space may be cold but there is no way to get rid of that heat except for radiators. Convection doesn’t exist in a vacuum.
Right, but conduction does work on the moon. You have the ground as a giant heatsink. While the surface does get pretty hot in daylight, I am guessing that heat doesn't go very deep so you could probably bury your cooling lines.
It just requires humans up there to dig and bury the cooling lines.
Probably a stupid question but how can it be cold if there's no heat transfer?
it's kindof neither.
Our normal sense of hot/cold is a measure of how hot the particles around us are. Space has so few particles, that whole paradigm breaks down.
Technically space is hot since temperature is a function of average particle movement and spaceborne particles are mostly moving stupid fast. Fortunately there are very few particles in any given volume of “empty” space so that translates to space being “cold”.
Only at night.
https://science.nasa.gov/moon/weather-on-the-moon/
Which sounds like a pretty big challenge for a nuclear reactor. Maybe they only plan to put them on the poles?
Go Thorium MSR and bury it underground and you don't really have to worry about it. Might need some modification for moon gravity but otherwise seems like the best bet.
https://www.thmsr.com/overview/
That was my first thought, but then my second thought was even more terrifying - how do you protect your nuclear power facility from celestial impacts? The moon must get pelted with thousands of little bits of space debris every day considering it has no atmosphere. All it would take is a basketball-sized meteorite to slam into the reactor chamber and possibly cause a meltdown.
Cover it with a ton of moon soil
We'll take a second moon, cut it in half, and use it as a shield for the first moon
That's a challenge that people are working on for sure. Likely some kind of radiant cooling, but it's a lot of heat.
Heat also dissipates via radiation, not just conduction. I would imagine that nuclear power on the moon won’t involve hauling a lot of liquid coolant/heat exchanger/energy transfer because liquids are wicked heavy, hauling that up to orbit and then landing it is gonna take a lot of energy. They do acknowledge that cooling is an issue they’re working on.
Maybe some kind of RTG? I couldn’t find an article that said what the NASA contractors chose to build.
No, RTGs just don't generate the kind of power you'd need. I mean, they're awesome for generating electricity for a long time, but just not a lot of it. No, these are fission plants.
Is solar power combined with battery storage not an option?
Not really. Current battery technology is to put it lightly not the type of thing you want to rely on for long term life support. Lithium ion the current go to for rechargeable batteries physically degrades as you charge it. One of the main things you can do to reduce this is don't fully charge the battery. For example if the battery degradation from 0%* to 100%** is a cycle then 50% to 80% is only 21% of a cycle. That'll extend the lifetime of the battery (not the capacity) by about 5 times! That's pretty significant but you lose out on 20% of the batteries capacity permanently, even as the capacity decreases from degradation.
You've probably seen the hype about Sodium batteries which are currently 50% less energy dense which just immediately means NOPE for use in space.
* Lithium ion batteries are extremely difficult to actually fully discharge (controller won't let you)
**Lithium ion batteries should never be fully charged it causes them excessive damage so the controller prevents this from happening
They do it on the ISS though?
Although Li-Ion batteries typically have shorter lifetimes than Ni-H2 batteries as they cannot sustain as many charge/discharge cycles before suffering notable degradation, the ISS Li-Ion batteries have been designed for 60,000 cycles and ten years of lifetime, much longer than the original Ni-H2 batteries' design life span of 6.5 years.
Electrical system of the international space station, batteries
Also related:
Peak of eternal light, Lunar North Pole
ISS doesn’t have a two week long Lunar Night where solar panels dont work
The eternal light idea is fascinating but even in the best case scenarios, you’d need batteries to supply all power for two full days. In the more prudent case since lives depend on it, you’d need significantly more to cover any outages
Meanwhile, 2-3 nuclear reactors strung out on different sides and with redundant connections, and you’re good for 20 years and many types of outages
Much less power for the weight, and weight is the big deal when you're sending things from earth.