Okay, we've covered the basics of what sets the Moon apart from Mars. Now we need to really understand the Moon itself. To get across the scale of the difference from Earth and the impact on Earth of a colony on the Moon, we'll start with an extreme case. If you let it soak in, the Moon will never look quite the same to you. Have fun.
Yes. Dr. Evil, Magneto, that kind of thing. Once a Moon colony was big enough to have a decent industrial base and launch facilities, it would command a strategic advantage over us lowly Earthlings not seen since the conquistadors ravaged the New World with guns and influenza. You will really, really want to be confident you trust them. So don't leave colonization to one or two countries you don't know much about, or to a haphazard private venture. It needs to be done right, and done soon. That way, when they realize they could make us bow before them like so many pet monkeys, they will nonetheless stick to their peaceful ways full of laughter and song, because after all life is good. It could be a century between now and then, it is true, but cultures tend to get established early in the history of a colony. Allow a belligerent culture to take hold in the next few decades, and that could seriously come back to haunt us.
Suppose the right melange of hyper-rational mal-contented perfectionists turned the Moon's culture towards an ambitious, ruthless vision of their natural superiority among humankind. Because you know what the profile of the typical colonist will be, right? Risk-taking adventurous techies tending strongly towards organization, discipline, teamwork, and rational analysis... basically like every navy ever. A tiny nascent nation of such people could leverage the math of orbital mechanics to stunning effect. They need to be self-sufficient and have the ability to refine ore into usable products first. I'd say the tipping point would be when they can bulk manufacture their own solar cells. That would likely mean they could also fabricate everything else they need. Then they could move decisively to implement the following, surprisingly simple plan.
Note that none of this is science fiction. The technology for this whole plan already exists. It would be an awful lot easier to pull off if you can bulk manufacture carbon nanotube cable, but by the time this is ready to roll that will almost certainly be true. The first step has been analysed in several different versions by scientists and engineers seeking a ways to cool our quickly warming planet, since it is pretty apparent we aren't going to be able to avert disaster by simply choosing to bring long-standing habits to a screeching halt. It would work but is widely discarded as impractical. That would not be true for our Moon colony. After that comes a few humongous lasers, because really, how could you respect yourself if you took over the world without some? And then it's all just location, location, location.
Step 1: At a certain point on a line between the Earth and the sun the gravities of the two bodies balance. This is called an L1 Lagrange point, they exist between every pair of bodies with significant gravity. Things placed there will remain in the same relationship to the Earth and sun until other gravitational influences perturb their orbits. To compensate for that they need to be able to maneuver just a little. Why not put a monstrous swarm of tiny autonomous craft there such that they deflect away about one to two percent of the sunlight that currently reaches the Earth? That would work. It would save us from the consequences of global warming, giving us time to perfect and switch over to clean technology before the climate goes completely haywire. If you are into this kind of stuff, Roger Angel wrote a pretty awesome white paper that is available in full online. He lays out details of how to put a swarm of 16 trillion light-scattering round transparent screens the size of hula hoops at the Earth - sun L1. The estimated cost is a few trillion dollars, or the equivalent of about 20 Apollo Programs, give or take. It would take a good ten years to complete if we hauled ass. It's doable, but, you know, you have to really want it.
We will eventually want it that badly, but a number of other geo-engineering ideas for this issue have been batted around that would be much cheaper, and between now and when we have to use one of them chances are even better ideas will be figured out. His idea probably won't get off the drawing board - for this application. But it gets ya thinking...
If you launched a system like this from the Moon instead of the Earth you could use a fistful of handy things about the Moon to make it much simpler. Then you can breeze past the point at which Earth is saved and move on to the point where Earth is also your bitch. Just broadcast a message to every channel on Earth from your mountain lair one day, in which you sneer with crazy eyes and whisper 'Winter is coming', then throw your head back and laugh, the way you practised in front of the mirror.
There are some challenges, so stay focused please. The pay-off here is world domination, it is worth the trouble. You can easily manufacture what you need in bulk, but you are going to need an awful lot of it, and it will be heavy to launch. You are going to make a mountain of very basic solar sails. You will need basalt of which you will have oodles, plus chromium, which is rarer but easily accessed. The basalt you will melt and spin into extremely fine fibers to make basalt fiber textile, which is light, tough, and very strong. You then make squares of this 20 metres on a side, cut along the diagonals into four triangles, and make a strut system and guy wires for those diagonals, also molded from fused basalt. The other side gets a delicate coat of chromium. Each then gets a simple microchip, a few small embedded solar panels and sensors, a radio receiver and some basic micro-controls.
They will be quite heavy as such things go, but they don't need to be fast or very maneuverable. They would be pointed in the right direction and all the velocity they needed to get to the L1 point would be given to them at launch, then minor course corrections and braking would be done by the sails as they journeyed to their destination. (Solar sails use the ever-so-tenuous pressure of all the particles flying off the sun to push them around, much like ordinary sails use wind.) Each sail would provide 400 square meters of shade and weigh about 10 kg. You will need 25 billion of them. Now don't panic. That is equivalent to the mass of about 2.5 years of paper production in China, or 2 months of car production in the United States. You may be daunted by the idea of launching 2 month's worth of American car production into interplanetary space, but fear not. You are on the Moon, my friend. You smirk at the Earth's puny launch capacity.
By the way, when i say 'you', i hope there is no confusion that i am encouraging you to become an evil overlord. I just think it is helpful to relate ideas in personal terms.
Step 2: This is the part where we get to talk about lunar sling launchers, the very coolest launch system you never heard of. No air, not much gravity - why not just swing a super-long, super-strong cable round and round so fast that you can fling a vessel off the end of it and it will actually fly off into space? Yep, you can do that. Space is fun.
Like this, but evil.
Especially on the scales we are talking about, you really need cables of carbon nanotubes or maybe rolled up graphene for this to work. If you have that, this is a system you have to love. The plan calls for 10 behemoth sling launchers working 75% of the time for 7 years to get our stuff all sent off. These babies can launch a million units in each launch cycle, and they can do that in about 18 hours. You know those swing rides at fairs? They are like one of those but giant, with 100 cables around the hub, and each cable has a rack hanging at the end that gets loaded with 10,000 sails before each launch. Then over the course of 3 hours the hub spins up and unreels the cables to a distance of 100 km, until the racks at the tips are turning at 3.84 km/s with an outward force of about 14 g. Over the course of 11 hours the racks empty, layer by layer, releasing a set of sails from each rack at the exact moment when it is pointing in the right direction. Thus, a constant stream of folded sails would extend outwards from the sling launcher in a straight line into the sky, zooming along like a sped-up trail of ants. Giant flying supersonic space ants bent on world domination. For 11 hours. It would even catch the sun nicely, make for great photos. Once the racks had all emptied, you reel the cables in again over another 3 hours, reload the racks, and do the same thing every day for 2500 days.
For future reference.
To be able to continuously launch like that you need to put the sling launchers at the Moon's poles. That way they always have a line of sight to the right trajectory. Both poles have convenient crater rims and mountains where you can build relatively short launcher towers capable of sweeping cables 100 km long around them without hitting anything or interfering with each other (yes, i checked). The poles are also handy because you only need two solar panel fields for each pole to supply all your launchers continuously with power. At each pole you will have to space them a few hundred kilometers apart, and then one will always be in sunlight - at least. Because you can take advantage of the Peaks of Eternal Light, most of the time both fields will be in sunlight. The Peaks of Eternal Light (why not say it twice?) are mountains and hills close to the lunar poles that receive sunlight 75 to 90 percent of the year. So you should only need a modest amount of power storage capacity to cover any gaps or outages. How many solar panels will you need? Around about 3 square kilometers for each field. Not bad, considering what you get.
The motors you need for your launchers are really nothing special, the electrical grid is ho-hum. The same goes for everything else involved in the solar sails and the launchers, except for the carbon nanotube cables. A mountain of people are researching carbon nanotubes, advances are regularly announced. Spools of carbon nanotube thread are already availablae. Numerous factories for basalt fiber will already exist on the Moon. The stuff is extremely useful and easy to manufacture there. There will also be factories producing a variety of molded basalt prefab building components that could be used to make the launcher towers. The key parts could be made from aluminum or titanium smelted and extruded in other factories. Definitely there will also be industries producing pure crystalline silicon then fabricated into solar cells and micro-controllers. A Moon economy has plenty of need for all these things, to make them independent of Earth, make possible construction and development on grand scales. Some of that might need to be scaled up in order to add in the project of conquering Earth. In particular, they would need about 40 continuous basalt fiber furnaces, each about double the size of the typical industrial furnace used for such things on Earth today. But that really doesn't sound outrageous, does it. I'm telling you, this is totally doable.
Alright. Let's say you have gotten all your sails in place, in concentric halo orbits around the L1 point, blocking out about 5% of the sunlight the Earth used to get. What would that do to the Earth? Well, it is hard to say clearly of course, but there are solid estimates that sound every bit as scary as what we are going for. The average temperature of the Earth would drop about 15 degrees Celsius in about 20 years. Which is a lot. If that guess is a little off and the result wasn't quite as dramatic, you could of course keep shipping sails out for another year or two until it was. After all, you don't want the Earthlings to hum and haw for a decade about whether to take you seriously. You want them to capitulate to all your demands nice and quick. The best outcome would be that you don't have to keep the sunlight dimmed more than maybe 5 years before New York City has snow on the ground in June and everybody starts to freak out. Then you can radio the sails to dilate their halo orbits twenty thousand kilometers and let the sunshine in again. And in return receive maybe Borneo, where you can have your new servants build an extensive space port so they can start shipping you all their best cheese, bacon, chocolate, and scotch.
Perhaps you are thinking Earth would just blow a bunch of your stuff up if you started annoying them too much. No they wouldn't.
Your key defence pieces will just be sitting there, doing practical, peaceful things. Large lasers will be common for use in mining operations. It might sound like overkill, but because of the nature of the Moon environment, lasers make more sense than mechanical drills or saws. The regolith is made mostly of fine, very jagged particles. Because there is no air or water on the moon, unlike on Earth, there have never been forces smoothing the edges of things. There are no beach pebbles, no wavy dunes. Instead, everything has been pummeled for billions of years by endless meteor strikes into a sea of blast debris covering the entire orb. The stuff is practically designed for making things jam. As well, there is no water to use for lubricant or cooling. Water will be mined or shipped from off-world and as such be a precious resource. You won't use it if you can't recover it afterwards, or it at least stays within a carefully managed closed ecosystem. Using drills or saws on regolith or bedrock will only result in a whole lot of seizing and overheating. What you want to do is plain melt stuff with a big laser, slicing it into slabs or boring into it so explosives can be set for blasting, or there is so much heat-fracturing that rubble results.
Point those things skywards and you have instant Star Wars. There is no atmosphere scattering and weakening their blazing light. There is nothing stopping you from aiming them at things hundreds of thousands of kilometers away with complete melting effectiveness. Like at missiles launched from Earth, for instance, or satellites that are looking at you funny. Even if Earth launched a thousand missiles at once - which would be extremely hard to do, even if they repurposed every intercontinental missile silo from the Cold War for the job - it would take those missiles over two entire days to reach you. There would be time enough to explode every single one with just one laser before they arrived. You'd have plenty of time to engage in witty repartee before sweeping the heavens clear.
What if Earth decides to go directly after the sails, instead? 25 billion tiny targets spread over an area thousands of kilometers across and tens of thousands of kilometers deep? I don't think so. Try to take out large areas of them with monstrous bombs? Well, there are no shock waves in space because there is no atmosphere, so except for the few occasions where bits of shrapnel have the incredible luck of actually hitting a sail, nothing is going to happen. And when they do hit a sail, they'll probably just put a hole in it and it will keep right on working.
Can Earth start using lasers? No. The atmosphere makes the light diffuse until after a few kilometers it isn't so much a laser as a spotlight. By the time it got to the Moon it would be imperceptible. Launch some into space and then use them there? Well, it's pretty easy to spot things being launched into orbit, rockets aren't subtle. If they started acting suspiciously the Moon crew would take them out before they could attack. So it's good that the Moon is such a great place to put telescopes. Never any clouds to block the view, Earth is never below the horizon, and there is no atmosphere making things fuzzy. Let's see. You will need two extremely sensitive infra-red telescopes separated widely enough that they can distinguish what objects are in the vicinity of Earth by triangulation. Those will watch the sky near Earth constantly for things that look like rocket engines firing. You will also need pretty great radar dishes. Aiming lasers at things in space hundreds of thousands of kilometers away is effective, but it isn't easy. You have to be extremely precise. Fortunately, unlike when you fire objects, lasers are a constant stream of destruction. If you are having trouble aiming at the exact spot, you can aim at an area you know the target must be inside, and sweep the laser around in it until you see the target explode. No wonder people in space shows use lasers for all their destructive needs. They are mighty convenient for that.
With so much at stake, Earth might come up with some clever ideas that could disrupt your plans. It would be a good idea to put a goodly number of monitoring satellites around it so you can always see the whole globe - ones that are especially good at spotting launches and calculating trajectories. And a bunch of missiles that can give chase to anything heading towards the L1 point, and some bombs in the leading edge of the sail cloud that can go meet any sizeable unauthorized objects. Just in case. Likely it wouldn't come to that though, and you could attain the perfect victory.
Step 4: The perfect victory? As long as everyone remained sufficiently clear-headed for the Earth to capitulate before bitter cold took many lives, and the Moon never stooped to directly attacking the Earthlings resisting their inevitable loss, and the Moon's demands weren't terribly onerous once they'd won, this scheme could yield utter dominion over our home planet without a drop of blood shed. Wow. So imagine what could be done if instead of conquest such great potential was directed towards peaceful purposes... Nah, scratch that. Let's ponder what it would be like to live under nerd overlords. Just a little. Just as a mental exercise.
Seriously. A few thousand techies achieve absolute rule over the entire Earth. A tweakable absolute rule - displease them and they can order around their sails to whatever degree they deem appropriate. They'd have like a dimming switch on the Earth. But they are just a bunch of nerds, really, enjoying their moonish ways in their shiny high-tech home beneath eternal stars, where everything is light. Earth can't touch them. What kind of dictators might they be? Is it not slightly tempting to think they might do an excellent job?
I don't imagine the demands of nerd overlords focusing much on inane things like extreme luxury, debauchery, or forced pageantry. I imagine them demanding all military spending stop and the resources be dedicated to comprehensive infrastructure projects, a list of which they'd kindly provide, with complete documentation and a wiki service. I picture them refusing to restore full sunlight unless every nation in the world allowed their Earthside representatives to inventory their military hardware down to the last bullet, after which that inventory would be shipped aboard the world's navy vessels to a spot above the Marianas Trench, and sunk. (If more ships were needed a bunch of petroleum tankers could also go.) And having a powerful triple redundant network of satellites set up to provide extreme broadband to the whole world, for free and uncensored. And requiring that all governments adopt a standard bill of rights, institute a Single Transferable Vote democratic system, and cooperate with election monitoring. And then maybe leaving it alone before they got sucked into micro-managing, so they could finally get back to the great Moon lifestyle they had been enjoying before Earth so rudely interrupted by being just too chronically stupid to put up with any more. Not that they wouldn't insist on keeping Borneo. Because sometimes a person just needs some blue sky, you know?
But this is juuuust a mental exercise.... That's aaaall we're doing here... We are juuuust noticing that when the Earth no longer bounds the human race, things change so much you have to let go of an awful lot of assumptions. Sometimes assumptions you may not even have realized you had. For all its glory, Earth is a tiny place. Seen from the perspective of the heavens, it is awfully easy to damage it. So we must protect it. It's our job, and nothing else matters.
Fertile eggs can be taken to the Moon and hatched there. All it takes is a bit of careful packing, as in high-school physics experiments where you protect such an egg from breaking after being thrown off a roof. Eggs. Yum. Chickens. Even better. A fertile chicken egg remains fertile for several weeks with no special attention at all. (But not long enough to make it to Mars. Sorry Mars.) This is probably true of many other kinds of eggs too. Once on the Moon all they need are three weeks under a heat lamp, and then you have chicks. When you are trying to establish an off-world colony, things like chickens are not only mighty handy, they have a wonderful feeling of home. And when they flap their wings and discover with the low gravity they can fly? Hilarious. Worth it just for that.
This would of course come at the stage when large greenhouses are already in place. They don't have to have a lot in them though. Chickens like their greens, and as they browse around getting them, and instinctively searching for bugs, they will nicely cover the planting surfaces of your greenhouse with valuable poo fertilizer. So, it would actually be convenient for them to fly around. Your greenhouse will be truly 3D, plants to the roof in big saucers carefully distributed throughout the scaffolding to maximize use of light and resources. It will take a long time before you have much of something that could reasonably be called soil - something a plant can actually grow in, instead of the barren Moon dust you will have to start with and carefully enrich. Each plant will get its own precious handful so that none is wasted. Where possible, plants will be grown hydroponically, in water loaded with nutrients.
There will be many other differences between moon greenhouses and such structures on Earth. On the Moon, heat control is a big issue. There is no air and no moisture to spread heat around. The sun is very hot, the shade is very cold. Plus sunlight is twice as strong on the Moon because there is no atmosphere. All day long - which is almost 2 weeks there - no clouds ever block it, nor is any of it absorbed or reflected by air molecules. It has all the radiation the atmosphere filters out on Earth: x-rays, gamma rays, and when a solar flare hits, ionizing radiation in lethal doses. The whole sky is also filled with cosmic radiation, which over time could cause a lot of health problems. To handle this, you make your greenhouse a cylinder with very thick walls of lunar soil, about as high as it is wide, with a transparent roof.
The walls act as thermal mass, heating slowly during the lunar day and then releasing that heat steadily through the lunar night. The squat cylinder shape keeps the plants as close as possible to that gentle warmth. At the same time, the walls block solar radiation. This works well if the greenhouses are built at high latitudes, much nearer the poles than the equator. (There are other good reasons to build in these zones, which we will get into in later sections.) The sun doesn't get too high in the sky there. You can reflect the amount of sun you want into the greenhouse from a mirror attached to the roof. Make the sunward walls higher than the shady side, and no direct sun will ever enter. The plants will never get zapped by ionizing radiation during major solar flare or coronal mass ejection events - and neither will you. This is good because those things can kill you in hours. They also block the vast majority of cosmic radiation - with 4 m thick walls, which are also convenient because they are thick enough to largely counterbalance the pressure of the atmosphere filling the greenhouse. The clear roof is still an issue. Unless it is over half a meter thick cosmic ray particles will punch through it like it isn't there. But that would be the only direction of exposure, so on the floor of the greenhouse overall you would get 15% of the cosmic radiation of being unshielded on the Moon 💬. That is about a fifth of the average dose astronauts get on the space station. As those astronauts have been fine (um, so far) after 6 month tours aboard the ISS, exposure like that for a few hours a day could be fine. At any rate, if you spent 4 hours a day in the greenhouse it would take you 15 years to accumulate that ISS dose (from there, never mind time you might spend outside). Because it is spread over a longer time your body has much more chance to heal any resulting damage. If that isn't enough to keep you healthy, then upgrading the roof would be in order after the first decade or so.
A warm diffuse light as on a lightly overcast day will fill the greenhouse. That's because the roof will be frosted glass. Sunlight of full strength on the moon would be hard on the plants, and besides, it is much easier to make a roof strong if it doesn't have to be very transparent. You only want to let in about half of the sunlight, so cloudy locally-made moon glass full of imperfections is fine. It wouldn't be there to seal the greenhouse anyhow - a strong membrane below it would hold in the air. It would mostly be there to protect that membrane. Micrometeorites hit the Moon all the time. The particles are extremely small but they move extremely fast. You definitely don't want to expose a material that can be punctured to that. Or to the radiation of the sun. The glass would also take a lot of strain off the membrane, passing the air pressure on it to the lattice-work of supports.
When the sun goes down and the two weeks of night start, clouds of small LED lights would come on just above each saucer of plants. They'd be nestled close to the leaves and a reflective umbrella would open to cover them so their light all goes to the precious plants. In this way the plants would get along until daybreak. The great mirror that brought in sun during the day would fold down and cover the roof. A curtain of reflective insulation would also cover the outer walls. Heat mostly moves by being passed from one molecule to the next by direct contact - no molecules, no transmission. A vacuum is the best insulation there is. So for the moon greenhouse, if you reflect back the glow of heat leaving the structure as infra-red light, you hardly lose any heat at all through the roof and walls. That leaves heat lost to the ground. Lay down a low load-bearing platform under the greenhouse floor, before you inflate the membrane that holds in the air. Put the flooring tiles and what have you on top, and heat loss through the floor is minimal too. There would be a vacuum in the spaces created by the platform, heat would only be transmitted through the posts and by infra-red emissions. In fact, your attention would need to be on keeping the greenhouse cool enough, not warm enough. You might need to leave the mirror and reflective curtain partly open to shed heat at night, and the shady side of the greenhouse uncovered during the day. You might even need some radiators going into the ground, at least for the first models. Later on the heat flows will be understood and can be balanced without that. There is plenty of heat and plenty of cold on the moon, it is just a matter of knowing what proportions and relations get you the temperature you want. The thick walls will be the critical factor, absorbing and releasing heat so temperatures change slowly. Thick walls are easy, fortunately. You would basically use a sandbag technique. There is dusty soil everywhere, just fill big sacks with it, tamp them tightly, and stack them well. Sacks of basalt fiber fabric would be ideal, and setting up a plant to make such fabric would be an early priority. But the first greenhouse needs to come even before that, so first time 'round they will be sent from Earth.
Then there is just the matter of what to fill your greenhouse with. Bugs also are born from eggs, making them just as easy to transport. An appropriate suite of them would be an excellent addition. They pollinate things as they fly around feeding, and fatten up your chickens. Bees, hoverflies, and beetles would all be very welcome, and some worms to work the soil. A few well chosen ants and grasshoppers would also be important. Those would be critical to keeping you well-fed. They are tasty little things, really and truly. It is a mystery how we got out of the habit of eating them in European cultures. In many countries they are eaten regularly. They keep very well, they can even be dried and ground into flour for long term storage (which can also help the squeamish be okay with eating them). They don't ever carry disease - they are too different from us to harbour germs we can be infected by. They convert the sugars and starches found in plants into invaluable protein and fat. With them, the right selection of plants, and a bit of algae and seaweed grown in shallow ponds, your diet would be well-rounded and tasty. Chickens and eggs would be an extra. Which is good, because you might have to work up to them.
The trouble with chickens is they normally eat a lot of seeds and grains. Now, since they will have no lack of the greens and insects they like they may adapt well to a diet where that is replaced with bits of starchy veggies like potatoes, and dried algae. If not, you couldn't afford to feed them. The edible portion of grain crops is 10% of the plant at best, that isn't nearly efficient enough. On the other hand, grasshoppers and ants will eat discarded leaves and stalks. Then you eat the grasshoppers and ants. That is a far better system. There are also other animals born from eggs that would be easy even from the beginning. Like iguanas.
As for edible plants, you want as wide a variety as possible, clearly. The growth of plants will be odd and some may have trouble adapting. Having enough solar panels and power storage to maintain the light levels needed through the night will be the big factor. With enough light, everything else should be easy to handle. Yields might be low until suitable moon varieties of your plants have been bred, but as long as you have edible insects that will eat the plant parts you can't, that won't be too big a problem. Everything else can be controlled - watering, temperature, humidity. There will never be pests, or plagues, or hail, or drought, or weather of any kind. You might be able to feed yourself completely from your lunar greenhouse in just a few years. The day when you can would be the day you don't live on a base, you live in a colony.
Alright, so this section is mostly talking about greenhouses, not chickens. The chickens get the title because they really give you an idea of what can be done on the Moon. The greenhouse structures have to be built, but once they have, you can really create a wonderful garden, largely because you are so close to Earth. You can bring butterflies to flutter by, finches and swallows to warble and twitter, snakes to slither, toads to hop, turtles to trundle about. Fish for ponds. Anything born from an egg can easily be brought to your new home. The Moon's low gravity will let you build big with relative ease. The first few greenhouses will have to be smallish. But think about walking into a round space, 100 meters (or yards) across and 100 meters high. That is huge, but roughly equivalent to a structure like that 16 meters high and wide on Earth. You are only dealing with a sixth of the gravity, there are no wind loads, the ground is bone dry and very stable once compacted. There is a tipping point beyond which building lots of big things really isn't hard. Imagine looking up and seeing almost pure greenery - leaves, fronds, flowers and stalks - and a few patches of bright white where the frosted panes of the roof dome scatter the sunlight as it passes through. A moonish jungle. As the years pass and there is ever more infrastructure, there could even be trees, and space for them to reach their full height (which could be very high indeed in the low gravity). This is what will make the Moon truly a home, not an alien outpost. The first time a human truly feels connected to it as their home, they will surely do so while sitting in a giant lush greenhouse, perhaps relaxing beside a pond watching guppies flit about, listening to the crickets chirp.
And then a chicken will fly by.
Less Gravity is More Fun
Earth - airtime 0.8 sec, height 1m
Mars - airtime 2.1 sec, height 2.5m distance 7.5m
Moon - airtime 4.8 sec, height 6m distance 18m
The illustration above is to scale. If you are athletic enough to make a slam dunk on Earth, you could jump lengthwise over a double decker bus on the Moon with room to spare. You would land as hard as you do after the slam dunk on Earth. The Apollo astronauts never got to have a lot of fun with this because they were wearing spacesuits that weighed 90 kg (200 lbs), and those suits were so stiff they could hardly bend their legs to get much of a spring.
Zero gravity is fascinating, but having a little gravity around is nice most of the time. Astronauts on the space station have to be careful to exercise in ways that stop their muscles from atrophying from lack of work, and their bones from hollowing out. They lose their appetite and tend to lose weight. They get puffy and congested because their blood isn't pumping around normally and their sinuses don't drain by themselves. There is concern that the low gravity of Mars and even more so the Moon might not be enough to prevent those problems. So it would be a good idea to bound around and lift things and throw things and do all kinds of exercise a lot if you are in either place. You may find yourself much more inclined to exercise under these circumstances. It will help if buildings are designed to take full advantage of the low gravity. Stairs? Who needs stairs on the Moon?
The gravity on the Moon is one sixth that of Earth. How life changes in that situation is so hard to anticipate there will surely be unexpected ways it influences Moon culture. To descend or ascend to a different floor you could jump up or down in two steps, thus making sensible moon stairs a series of holes with large blocky things nearby that could double as shelves or something. And that is considering floors that are a good 3 m high (10 ft). Just regular walking is going to involve a certain amount of springing simply because our legs are so overpowered for the job. For comfort a bit more headroom will be nice. Anyhow, on the Moon, if you can't easily jump onto a platform 1.5 m high you definitely need some exercise. As mentioned, maintaining a certain fitness is even more important there. A lot of people would have little trouble jumping straight to another floor in one go. Some people could jump two floors. (Optional fold-out ramps could be available for toddlers or sick people or whatever.)
You know how hard it is to open a door when you have your hands full, right? A plausible solution to that on the Moon is to toss what you are holding in the air, open the door, and then catch the stuff again. You have 6 times as much time to do that, and the objects will be moving at one sixth the speed they would be on Earth when caught. With a little practise you could neatly pluck several things out of the air as they came down, or rebalance everything on your tray. Trip with a whole tray of dishes? Again you have a lot more time to regain your balance and you could recover much of the time, but if you didn't, it would all play out very differently. First, for true wincing appreciation of the ensuing mess, it would take six times as long for everything to hit the ground. You would have time to frantically grab at things and hopefully at least recover most of that terribly expensive mug of coffee. For the rest, it would hit the ground one-sixth as hard, saving on broken dishes and splash damage.
Many people enjoy keeping fit here on Earth by running regularly. Running on the Moon would be an adventure in learning how to do that all over again. You would save so much energy because you don't have to mostly push upwards with each stride that, as far as the force at your disposal, your legs could kick you forwards at speeds that would make a cheetah's jaw drop. (At least you could outside, in the vacuum. Indoors air resistance would limit you to about Usain Bolt speeds, without the hassle of having to be in particularly good shape.) Runners on Earth use 4 times as much energy pushing vertically as horizontally. If it were possible to adapt your gait to apply all that force horizontally, you could run at well over 100 km/h (60 mph). But is that gait possible? Nobody has been able to figure that out. Experimentation is obviously necessary ●.
A few things can be said though. One: the key thing is you would need to lower your center of gravity, as you do on Earth when you need to push forwards hard, like if you are pushing a car. It is the only way to direct your leg's force mostly backwards. If you did this, you might need an aid to keep your torso stable - maybe ski poles. Two: you would have the luxury of accelerating slowly. Maybe you can only manage to use a small part of your strength to push horizontally. There is still no air resistance slowing you down, and the force you need to apply to maintain your height above the ground (i.e., to not fall) is so small you could keep that up for a very long time - it would be less strenuous than walking on Earth. So even if you are only bunny-hopping like the Apollo astronauts did, as long as you push backwards with each hop, you are going to pick up speed each time. Three: unless you can swing your leg as it hits the ground at least as fast as the ground is passing under it, you are going to fall. A home experiment determined that the fastest i can swing my leg through the air is 54 km/h. If my legs were as long as Usain's, that would be 66 km/h. Considering the potential, that is sort of disappointing. Maybe there is a way around that. Stilts come to mind. Not really long ones, another 50 cm would get me up to 80 km/h. And ski poles are already involved, anyhow. Four: this pursuit requires serious safety equipment. A full body air-bag deployment system seems advisable. Those snazzy light form-fitting space suits that have been prototyped recently are also clearly a must.
So what do you say, would you pay to see a broadcast of a foot race like that? Hee hee...
Still, for ordinary exercise, you'd be better off jogging with 5 people on your shoulders. Just be sure you all practise the stopping process, wherein your companions tip off your shoulders like a felled tree and right themselves before they reach the ground. For that matter, arranging to walk around like that as much as possible would be a great way to keep your bones and muscles in Earth-worthy shape. You'd need something more for your arms. I don't know, juggling watermelons maybe? Juggling would be easy at one sixth the speed. Or you could get into those rings that gymnasts do those things on in the Olympics that look so very difficult. Even if you only weigh 12 kg, it would still be good exercise, and they must be fun.
As for sports, obviously stuff is going to need to be invented. Pogo stick rugby. 3 dimensional racquetball. Vertical racing up cliffs.
Oh, and also you could fly by making big light-weight wings and flapping your arms. Why don't we come back to that one once we start talking about the architectural design of the Moon colony. Okay?
There's a star to wish upon
Sometimes audacious is appropriate. The mind needs to get accustomed to larger horizons, especially when they have leapt outwards quite suddenly. Humanity has a natural appetite for focal points that represent the power of ideas. Truly powerful ideas have truly powerful focal points. People's faith in those ideas is largely based on how impressive the things they cause to be created are. Rockets are thundering spectacles, but they are ephemeral. The International Space Station is inspiring, especially once you see it cruise overhead at dawn or dusk a few times, bright as Venus. But no, it just doesn't get across the scale of what we are moving towards here. Something truly otherworldly is needed, something that is striking as soon as you see it and then patiently works its way into the mind ever deeper. The change afoot is pervasive. To get across what it means something like the illustration is needed. The Moonstar.
Audacious as it is, creating the Moonstar is easier than you might think. It would take a mirror about 2 km2 in size. When the Moon is in the right spot in its orbit, that mirror would reflect the sun towards the Earth. It would be roughly as visible as shown in the illustration. Each of many sections making up the full mirror could be laid out and aimed well, and they would regularly cast light on the Earth - but only during occasional chance alignments, and only briefly. To get your money's worth, each section will have to be on a post that acts as a central pivot, and be able to tilt about 40o in any direction. With a motor on each pivot, the Moonstar could cast light on the Earth for several days as the Moon approached and passed full, slowly brightening as the alignment of Earth and Sun allowed it to reflect more directly. Each time it appeared in your area, it would remain visible for up to 4 hours, appearing, brightening, and then dimming each night. Over the course of 6 nights, it would track so that different parts of the globe receive its light. Almost the entire world would see it for at least a few hours.
The Moonstar isn't something that would be a feasible project in the early days of a Moon base, but after a decade or so, with some infrastructure and ships shuttling back and forth regularly, it wouldn't be all that hard. The main thing would be that you'd need to be able to make all the structural elements for the mirrors with local materials. If you can, then you are also able to build all kinds of other things. So we are talking about a point at which there is the beginnings of local industry, when there would be a lot of construction going on and the molded basalt materials for that could also be used for the Moonstar. The trickiest bit would be making really flat panels with a very even surface, so they can be coated with aluminum and become mirrors. Most of the basalt found in the lunar maria is easily made into a glass if it is melted and cooled properly, that would be the perfect surface. Lunar basalts can also be processed into beams, rods, and fiber materials like cable and fabric. Furnaces will be needed for the fabrication of those building elements (probably heated by concentrated sunlight). Any furnace on the Moon can easily be adapted for vacuum deposition, because the vacuum is already there. That's how the glass panels would get their micro-thin aluminum coating and become mirrors. In fact, another thing that needs vacuum deposition is solar cell production. Clearly locally manufactured electrical generation gear is hugely important. Maybe by the time a project like the Moonstar could make sense, the solar cells for it could come from the Moon itself.
What you would need from Earth would be the motors, pivot mechanisms, microchips, and wiring to make the mirrors track properly, the aluminum to make them mirrors, and maybe the solar panels too. But the mirrors only need to move a bit, and quite slowly, and also the sun is strong and constant. You can get the job done with motors and panels that are pretty small. The mirror coating can be under half a micrometer thick, so you don't need a lot of aluminum. Let's say 10,000 motors, pivots, and solar panels, plus the aluminum. You'd need only a ton of aluminum. The rest is harder to assess. Considering the low gravity, and how slowly and slightly the mirrors need to move, i'm going to say 1 kg of kit per mirror should be enough, making their total mass 10 tons. The generation of heavy lift rockets due to appear in the 2020s should be able to land about 20 tons on the Moon (the SLS and the Falcon Super Heavy). Altogether this project would occupy a bit over half of the payload for one heavy lift rocket. The cost of the equipment itself would be insignificant next to the cost of that transport. Another option is send them up over time on regular scheduled flights. Extra room on such flights might be rare, but this project is going to take some time. Probably something like 5 to 10 years to be fully ready. So possibly there would be enough room to just coat-tail the needed materials on scheduled flights with extra room, further reducing direct investment in the project.
Now i have done everything i can to knock down the overall expected cost of this project. It is an idea piece. Its perceived value is its entire value. Such things are much easier to see done if they aren't a big hassle. A lot of people would see no benefit to being able to look up at the Moon and see a tiny star on its face. A lot of such people vote on budgets. But let me make the case that the value of the Moonstar would be subtle, grow with time, and have a broad cumulative effect. Which brings us to a discussion of its merit, and what it is worth. Let us talk now a bit about our ancestors.
Once upon a time, when the world was young (at least, we thought it was young), the peoples of Earth went on quite a building frenzy. Pyramids. Everywhere. They were built for many centuries and got bigger and bigger and bigger. And more elaborate. We also built a lot of megaliths and other huge stone things and sometimes we aren't quite sure how any more. This fervor for gigantic projects eventually burnt itself out and has never returned. It is important to remember that compared to any kind of building project since, these undertakings required a huge proportion of the tiny economies of the very young nations who built them - being all of the nations first to appear on the face of the Earth, on each continent. Why did we do it? Why did all of us do it, every single nation, during the course of becoming self-aware as a nation?
Because we thought it meant something. We genuinely, in our heart of hearts, believed we were honouring our gods and that this would bring great fortune to our nation. We thought we were part of something very special, something magical, and we strove with everything we could spare to experience that sense of specialness as real and important, our fate, our purpose. Aaaaand that didn't work out so well. Talk about a disappointment. I mean, alright - i don't want to demean the significance of the achievements. We still look upon them with awe. They taught us how to work together for a larger goal. The complexity of these undertakings was huge, it truly required organization, concentration, discipline, and effort of an astonishing degree for the tender small nations that built these things. I would even hazard to say we have never since managed such singular achievements. Many of them are jaw-dropping. Just a few decades ago we cynically assumed only slavery on a massive scale could have yielded such huge, glorious things. But they weren't built by slaves. It was an honour to participate. There are no modern equivalents.
Well... maybe one modern equivalent...
But it didn't bring fortune to our nations the way we thought it would. Disease and famine and war still came, and eventually we must have concluded it just wasn't worth the effort. Especially once we realized our kings weren't minor gods themselves, or favored by the gods, like they claimed. Or perhaps it was more that as each individual nation succeeded in establishing its identity, anchored in good part by the impressive accomplishments of the pyramids and monuments that displayed its power, the urge to prove something was satisfied and there was no further need. At any rate, we got over it and moved on.
That is, we scaled down. We built temples and palaces, and still do, but those things don't come close to the kind of investment those ancient undertakings required. And neither would the Moonstar. It would just touch that same ancient itch to see what we can do, whisper to that same collective urge to grow, be part of something special. It would do this like all human monuments have done, all the things through our history people have gone on long journeys to see with their own eyes, or gotten images of if they couldn't go themselves. Except the Moonstar would have one extraordinary difference. It would come to you.
The Moonstar would be equally visible to the richest and the poorest, to the most remote cabin and the biggest city. It would change the whole context of human monuments. Yes, like other great monuments, it would be there to demonstrate our capabilities, our values. Unlike any other monument, it would not do so by making us feel small before an authority. It would tap into our childlike instinct to wonder at the heavens. It would take the tradition of making wishes on stars and using them for fortune telling, and turn it into a challenge. We make our stars.
The Moonstar would be the undeniable demonstration of what we are capable of. It would call across the void, from the heavens that have always been the seat of our faith, and say the childhood of your species is over. You would have no choice but to ask yourself, if the very face of the Moon can be changed, what limits are real? What limits exist only in our minds, to defend choices ultimately unworthy of us, unworthy of the power we possess? What pursuits truly are worthy of such power? How much greater would the changes wrought by them be, than a mere star on the Moon?
And perhaps you would then notice that as you pondered these things, you pondered the sky itself.