29 thoughts on “Artemis”

  1. I’m not sure why anyone would consider the Moon to be a place where solar energy is insufficient. It’s probably one of the only places in the Solar System where solar would be preferred.

    For two weeks at a time, one has access to the full 1,362 W/m^2 of sunlight here at 1 AU, unfiltered by an atmosphere. There’s no wind to pick up dust to soil the mirror concentrators. There are no birds to be fried in flight. And at the focus of such a mirror is 6,000 K power!

    Smelting takes heat, and heat only. No need to use PV panels to provide electricity to run furnaces. Just use the raw Sol power to melt directly!

      1. Lunar nights are long but so are the days. Use the thermal and electrical energy collected during daylight to keep things warm and powered at night.

        1. That’s a LOT of batteries. Though you might save some by running energy intensive industries only during the lunar day.

    1. “Smelting takes heat, and heat only.”
      Not most smelting processes I know of.

      Iron needs a reducing agent. Carbon is used on Earth, but hydrogen might be used and more easily regenerated.

      Aluminum smelting uses consumable carbon electrodes, and a LOT of electricity.

      Copper can be smelted by just heat, but a reducing atmosphere helps. And the ore is much harder to come by than iron or aluminum.

      1. –peterh
        December 8, 2017 at 8:39 PM

        “Smelting takes heat, and heat only.”
        Not most smelting processes I know of.

        Iron needs a reducing agent. Carbon is used on Earth, but hydrogen might be used and more easily regenerated.–

        In cold lunar crater, there suppose to be CO and CO2.
        Of course there is limited, but you can split CO2 into CO + O
        Thereby have unlimited source of CO to react iron oxide which makes iron and CO2:
        Splitting CO2 into CO and O2 by a single catalyst

  2. Not having read the book yet, I suspect the reason Weir went with nuclear is because it is too costly to bootstrap with solar alone. So once you assume nuclear its much easier to scale it to what you need.

    You can’t make solar cells from silicon alone without the proper dopants. If those elements aren’t abundant on the moon they’d have to be brought up from Earth. The sheer bulk mass would not be something to sneer at, if far less mass of enriched fissiles yields equivalent or more energy. That unit of efficiency is called “specific energy” I believe?

  3. Just finished the book. Decent read. Not very “spacey”, though — Coulda used more EVA action, IMHO.

  4. Weir has put his finger on the problem with the moon. It’s a place to visit, not a place to live.

    Only a place offering independent self sufficient colonies will develop economically. That’s mars, not the moon.

    Insects will compete with algae as moon food. But either way, the chemical nutrients will have to be imported (and most inexpensively from mars.)

    1. That’s mars, not the moon.
      It doesn’t necessarily have to be another gravity well. Have you read The Expanse series of novels? Tycho Station, primarily a big space station shipyard, is such a hub.

      1. No it doesn’t have to be a gravity well. Two factors rule, delta-V and material availability. A secondary factor, but extremely important, is infrastructure. As gravity wells go, mars is well positioned.

        The dV for most micro-gravity rocks will be more than from mars. Those that are less will likely not have all the materials and difficult to scale. For infrastructure, most rocks would depend on it being part of the ship (or more likely a specialized ship from a group.) On mars, that infrastructure will be distributed (with competitive development) which is much more efficient. Scaling on mars will be almost trivial.

    2. That’s almost certainly true. But the Moon remains a good place to learn, initially, how to live and work on another world. Much cheaper and faster to reach and supply. And while we all have our doubts about how well humans can live and flourish long-term in 0.16 gravity, it’s also not clear that Mars’ 0.38 gravity will be adequate enough, either.

      But unless someone is prepared to invest in centrifugal gravity stations in LEO, there’s only one way to find out.

      1. The moon is fine, but it’s guaranteed people will learn the wrong lessons that do not transfer to mars.

  5. Just finished reading “Artemis”. Good little story. Wrong place for Moon city as it needs to be at the poles and it is set in the early days of the humans on the Moon so no great industry/food raising.

  6. It seems iron would be building material of choice.
    The weight of iron- 7.8 / 6 = 1.3 tonnes per cubic meter
    on the moon, or half weight of AL on Earth.
    In terms of strength to weight, AL is stronger than on Earth
    or the Moon. But iron has higher strength to weight on the
    Moon as AL has has on Earth.

    What is valuable on the Moon is pure iron and iron oxide more
    value, because it’s low energy way of making oxygen.
    And magnet will get you iron, iron oxides. and other magnetic
    material. Once remove most of oxygen from Iron, you have piles iron
    and other magnetic material. Just melt all of it.
    So in terms value, iron oxide should be more valuable but iron and everything else would also have value- piles of it could be bought to make building material, and lots of other things.
    AL would fine if could get pure AL or pure oxides of AL

    And obviously for any kind settlement- including hotel, one would want access to water and rocket fuel. So lunar polar region..

    1. Daytime on the moon has better solar energy than mars that mars might export iron oxide to the moon?

      1. Mars surface surface has solar energy roughly equal to Earth surface. The Moon has much much solar energy than Earth surface. The moon has better solar power than LEO, but of course not better than GEO.

        The location of lunar polar region is good location to start a economy which can be solely powered by Solar energy.

        Of course one could say farming is economy based on solar energy, but I mean solar energy to provide electrical energy.
        Of course nuclear power would work on the Moon, but I think you need nuclear energy to support modern industrial civilization on the Moon- you would need nuclear power if Mars needed a large amount of electrical power for industrial use.
        You could get all electrical needs of Earth from lunar solar power- it doesn’t make economic sense, better to make the components for Earth SPS on the moon and ship to GEO. At launch cost of less than $1 per kg to GEO. Though it’s certainly arguable that one use building material from asteroids and not build Earth SPS on the Moon.
        But if going to make Earth SPS on the Moon, one needs time for Lunar launch cost to lower from beginning price of around $2000 per kg to Low lunar orbit to point in time where it’s around $10 per kg to Low Lunar orbit, before making much sense to plan it doing this. So this could take a few decades after lunar water starts being mined and made into rocket fuel.

        But at this point in time, we don’t know if the Moon has minable water or that Mars is viable for human settlements- exploration is needed, and it’s possible someone other than NASA will actually do this exploration which is required.

  7. All of the things I have read about ISRU on the Moon seem to be jenky underpants gnome scenarios. They sound good and are based in what is possible but also free of specifics and being impossible to do right now.

    At some point imagination needs to be put to work accomplishing things in reality. There is no way to plan out mining and processing without being there to work through the process.

    To bring this back on topic, speculation about site selection and what could easily be grown for food are things that have a bearing on what we could do now. Books are great at firing up the imagination but c’mon let’s gooooo!

    1. Exactly right Wodun. They always seem to look at ISRU in isolated case, instead of considering the entire periodic table which forces highly expensive import of some essential elements.. Mars is the only place in the solar system that competes with earth in diverse resources. Yes, the rocks in space have more but distributed. Some elements will be economical from those rocks. Mars will have all.

      Earth advantage as a source is infrastructure but that will change rather quickly (although stupid short-sightedness does slow it down.) Mars just needs people. They’ll build everything else.

    2. —wodun
      December 8, 2017 at 3:56 PM

      All of the things I have read about ISRU on the Moon seem to be jenky underpants gnome scenarios. They sound good and are based in what is possible but also free of specifics and being impossible to do right now.–

      I would say lacking specific exploration.
      Basically ISRU is about lowering an exploration cost.
      A better way to lower exploration cost is to do the exploration program within a shorter period of time.
      Obviously ISRU would not helped lower cost of Apollo program- granted that the Apollo program was not a exploration program [it was a race to the Moon].
      ISRU is similar to Shuttle program, and the shuttle program didn’t lower costs.
      One should make a base to lower exploration costs, a lunar base doesn’t lower cost of exploring the Moon to determine if the Moon has minable water.
      Whereas base on Mars could lower exploration costs of exploring Mars. Don’t build lunar bases to explore the Moon to determine if and where there is minable water. If there is minable water which is being mined, one could put a lunar base near that area.
      But explore the moon and finish the limited objective of determine if and where there is minable water, within a short period of time- less than 10 years. And explore Mars to find good location for exploration base, build and use base.

      1. Basically ISRU is about lowering an exploration cost.

        It’s much, much more than that. Obviously that’s how Zubrin presented it, but ISRU is about the viability of the local economy more than about making it less costly to get there. If you are only going one way, it doesn’t necessarily reduce costs at all (except it would require dying on mars at mission end, so impractical.)

        Having sufficient resources that aren’t imported makes growth a given and sustainable.

  8. Telecom guy here. He really screwed the pooch on the fiber optics. The book said that you had to regenerate the signal every 15km.

    We can get 12,000km in the lab. And in production, we already hit 1500km without major issues.

  9. Weir is retelling popular science fiction stories from the late 1940s and early 1950s, with modernized space science. I’m not surprised people have forgotten about long-dead authors like Rex Gordon. I wonder if Weir’s next blockbuster will be a retelling of Ride the Gray Planet, by Blake Savage, a 1949 tale of a Planeteer crew assigned to divert a thorium asteroid to earth orbit for mining. I read it as a little kid in a Whitman hardcover retitled “Assignment in Space.” It was pretty good, with the plucky spacemen of the Federation of Free Governments battling for control of the asteroid against naval forces of the Consolidation of People’s Governments. Well, 1949, y’know. Weir can change it to a platium asteroid, to build catalytic converters in the war against AGW. I can just see the heroic Democratic Antifa Justice Warriors against evil elements of the Republican Christian Business Axis! Oof. I’m getting carried away…

    1. That just means he’s making SF great again! I really miss Heinlein. “Have spacesuit, will travel.”

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