Science magazine has an interesting article:
Moon safe for long-term human exploration, first surface radiation measurements show
But I am not sure the details are as encouraging as the headline. It's about how some recent dosimeters on recent moonlanders have given a more accurate idea as to the amount of radiation astronauts would be exposed to while staying there:
The device measured hourly radiation rates and found that astronauts would be exposed to roughly 200 times the radiation levels as people on Earth, they report today in Science Advances. The dosimeter’s placement inside the Chang’e 4 probe provides partial shielding, much as an astronaut’s spacesuit would to their body, so the findings are quite applicable to human explorers, Wimmer-Schweingruber says.
The measured dose is about five to 10 times what passengers on an intercontinental flight from New York City to Frankfurt, Germany, receive when the plane is above parts of the protective atmosphere, Wimmer-Schweingruber says. Though high for Earth-based standards, radiation is one of the known dangers of spaceflight. NASA is legally prohibited from increasing the risk of its astronauts dying from cancer by more than 3%, and these levels remain below that.
What’s more, the researchers calculated that Moon bases covered with at least 50 centimeters of lunar soil would be sufficient to protect them. A deeper chamber shielded with about 10 meters of water would be enough to protect against occasional solar storms, which can cause radiation levels to spike dramatically. (Between the Apollo 16 and 17 missions, the Sun flared up in a way that could have caused radiation sickness, vomiting, and possibly death had astronauts been unprotected in space at the time.) Such a chamber would need to be reachable within 30 minutes, the amount of advanced warning time that is now possible with monitoring satellites.
Why the heck are they talking about 10 m of water on the moon, as if that's what would be readily available to use for your emergency shelter? It's going to be a long, long time before there's that much of it available for colonists.
If I recall correctly, Gerard O'Neill's work on L5 colonies used to argue that your would need about 2 to 3 meters of moon dirt packed around one of his gigantic space colonies to provide adequate radiation protection. Is that the same effect as 10 m of water? I don't know. I want to know how much dirt moon stations are going to need to bury their shelters under for an emergency shelter.
Oh - and let's not forget - this need for radiation shielding is one of the key reasons why they may as well be looking at old lava tubes as a place to building a station. Although, the other thing is, I don't know that there are any near the South pole, which I think is where they think the ice may be?
3 comments:
With regards to the water, you ought to have the ten metres of water up there already well before you attempt to get a man up there. You want a great accumulation of water. To get oxygen, for drinking, for growing food, For reconstituting the water into fuel. To control temperature. To provide water for all the animals.
You should be able to get robots to dig holes and store water so you want to do things in that order. You'd never take the water up in the same craft that you'd take the men up in, except of course for their travel needs. Water is really heavy and it doesn't get damaged when you shoot it out of a hydrogen cannon.
They took anti-gravity covert in the late 1950's so nobody really knows how the deep state is going with that project. We get an indication from flying saucer sightings but not a real good indication. I suspect they would be out of energy pretty quickly regardless of their seeming excellent performance.
Lets put that aside .... In that case the only economically sound way to do things is to put as much into orbit with the hydrogen cannon as you possibly can. Leave all that water up there in the shade. You've got to keep your stash at all times using the earth to shade your stash. This is to stop water phase change and therefore an horrific explosion.
Its only when you had a tonne of water that the project could go ahead. The first people up there would be the guys fixing the computers that had broken down digging caverns and stashing water and other goods subject to the hydrogen cannon. Robots would be breaking down the whole time.
That s if you are doing it for real this time and not some fake-ass Mars rover project or the Apollo fiasco.
Consider what you have will all that water? Since the solar wind is electricity you have free fuel all the time when you have water. Free oxygen and free fuel since you have free electricity. So yeah the water is a big deal and you want a great deal of it.
With the water at the South Pole? Yeah I'm sure they will be able to use it eventually. But it cannot be the starter water because it will be chockers with deuterium. As well as bizarre isotopes of oxygen.
Now being as they have unlimited electricity available, once they are fully established they may have a good way of separating the heavy water from the light water. But I don't know how they are going to do it. To separate the two you want lots of gravity and less air pressure. Plus a very tall distillery.
Well you have less gravity on the moon. So maybe you'd have giant centrifuges and things. It wouldn't be easy to do even though on earth the real problem is energy. So as a result the water they send up in the hydrogen cannon is going to have to be deuterium depleted. This is a big process if you are doing it for real and not just for the television cameras.
I think these projects might wind up in the freezer for one hundred years. We don't have the oil supply for this kind of thing any more.
Possibly 2-3 metres sounds okay from the point of view of radiation. But you need redundancy and all bases covered. So at first the robots dig tunnels to where the main body of the starter colony is deep enough to not feel the difference between night and day, summer and winter with regards to temperature. Its only when you have your unlimited electricity set up that you can afford to be more adventurous.
When the first dudes get there, they've got so much fixing robots and animal husbandry to attend to. Such a waste of time sending people up there before the basic structures and raw materials are sorted.
But if its just a television production like Apollo or if their anti-gravity is fantastically advanced you can disregard some of what I am saying here.
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