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Why Mars Instead of the Moon?
Maybe I am influenced by having read Robert Heinlein’s The Moon is a Harsh Mistress when it was first published, but I am wondering about all the recent PR for a manned mission to Mars — even by some people who are not named Robert Zubrin — and whether it is just the romance of going to another planet. The Moon seems to make much more sense for a first permanent base (i.e. not an orbital space station) for a number of reasons:
- It’s closer.
- There is micro-gravity.
- If you go underground, you might be in decent shape for protection against high energy particles.
- There appears to be water ice in some of the craters.
- Mining on the Moon might, or might not, be worth the effort of going there. (Isn’t a useful isotope of Hydrogen available on the Moon and not on Earth?)
- The Moon, being out of the deepest part of Earth’s gravity well is, from a propulsion energy perspective, about halfway to anywhere in the inner solar system.
So what are the arguments in favor of Mars and against the Moon, besides “been there, done that?”
Published in Science & Technology
It’s a long, uphill climb back from Venus. It’s a downhill fall from the Moon, Mars, and other bodies outside our orbit.
Eric Hines
It’s interesting to think, though, that it takes more energy expenditure for a probe to go to the sun than it does to go to Pluto. This is because of the amount of kinetic energy that we have in traveling with the earth at its high orbital speed.
Does that include the climb back up the sun’s gravity well? I would have thought aerocapture/aerobraking at Venus would let us play pretty fast and loose with the fall inward, so the downhill delta-v wouldn’t matter so much (yes, I’m contaminating the pure energy exchange of the trip).
Related is the point Mr Koler raised. Using Mercury as our launch point (bacause there are aliens there), what are the relative energy requirements for getting to the Sun vs getting to Pluto? Is that sort of thing pretty much the same throughout the solar system, or are we on a gravitational cusp, like we seem to be in a solar energy cusp?
Eric Hines
Sheesh! All this talk of space colonization and no mention of the possibility of terraforming? Given advances in nano-tech, in virology and biology, isn’t it conceivable that we could transform Venus or Mars to be more Earth-like? I lack a strong science education, so I would like to hear what those with more of that background say about that.
I was going to make a very similar post the other day, but never got around to it.
I agree with the OP 100%. The moon is where we should be going first, for many reasons.
There have been two major discoveries in the past few years that make the moon a prime target. One is that we have proved the existence of huge hollow ‘lava tubes’ on the moon. The second is that we have discovered a LOT of water on the moon.
In my opinion, these two discoveries make the moon much easier to colonize than Mars. The lava tubes are a big deal.
Consider the problems with a Mars colony: Mars lacks a magnetosphere, so cosmic ray bombardment is going to be a constant problem. Even if Mars had an atmosphere we could breathe, we couldn’t spend a lot of time outdoors because of this.
And of course, we can’t breathe on Mars. The atmosphere is so thin that it’s more of a problem than a solution. It’s not thick enough to allow us to breathe or grow things on the surface, but it’s thick enough to cause constant dust problems, to conduct heat away from things, etc.
Any ‘terraforming’ effort is going to take thousands of years to have an affect. So if we colonize Mars we’ll be doing it underground or in protective domes.
The Martian soil is also chock full of perchlorates in concentrations toxic to humans. The entire planet is pretty much poisonous to us. And the perchlorates would be mixed in the fine dust that blows around on Mars and gets into everything – including any habits we build. Hard to keep dust out.
Self-sustaining colonization of Mars also requires the existence of a self-sustaining technological manufacturing ability, since it’s far too expensive to ship the amount of goods to Mars that a self-sustaining colony would require. But a self-sustaining high-tech manufacturing capability would require hundreds of thousands of people at minimum. Our technological capability on earth would probably collapse entirely if our population dropped into the millions.
So while we might be able to put a rudimentary manned mission together and land one or two dozen people on Mars in this century, building a self-sustaining colony is so far in the future that we might as well just call it science fiction and ignore it.
From an economic standpoint, Mars has nothing to offer Earth other than tourism and adventure, and therefore there is no profit motive for maintaining a permanent colony. We would be reliant on the whims of government to keep the whole thing going. Good luck with that.
So why is the Moon better? Next post…
Now let’s talk about the Moon. It has the same cosmic ray problem as Mars. Being airless, it also has the problem that the surface is bombarded with micro-meteorites that can ruin your day if one hits you. The surface temperatures range from extremely hot to extremely cold. It looks like a ball of dusty rock and not much else. So how is it better than Mars?
Well, for one thing, you can live here:
What you are looking at is a ‘skylight’ into an underground Lava Tube. Lava tubes are formed when lava flows and the outside ‘skin’ of the lava hardens. Then under certain conditions the lava drains away, leaving a hollow ‘tube’ behind. That these tubes have existed on the moon has been a matter of speculation for a long time, but in the last few years inspections of new images from the Lunar Reconaissance Orbiter and the Japanese Kayuga orbiter have found hundreds of these ‘skylights’, or areas where the ceiling collapsed giving us a view into these tubes.
Now, a lava tube on Earth is usually not that large – maybe a few dozen feet across. Lava tubes of that size would make a good home for a handful of astronauts, but that’s about it.
But the lava tubes on the moon may be gargantuan. That ‘skylight’ in the picture above is about 70 meters across, and the floor of the tube below it is estimated to be 80 meters down. The tube itself may be as much as 500 meters across, and perhaps miles long.
This is nothing, though. The ‘sinuous rilles’ on the moon are thought to be collapsed lava tubes, and they are as much as ten miles wide. New research has suggested that lava tubes might be structurally stable even if more than a mile wide. So we may be talking about underground habitats large enough to house tens of thousands of people.
But it gets better. One of the discoveries we’ve made is that these skylights don’t just exist from volcanic flows, but they’ve been found in the maria and in impact ponds inside craters. The craters are interesting, as they often create ‘lava domes’ as pressure wells up lava from an impact and it hardens. Some of these domes may be hollow – and gargantuan. Here’s an example of a dome that would be structurally stable on the Moon:
That’s the city of Philadelphia, placed inside for scale. We are now talking about a structure that doesn’t look like a ‘cave’, but more like a self-contained world with its own sky, lakes and rivers, and whatever else we want to create.
This is a picture of an old concept for a space colony, but it helps understand the kind of environment we could build:
Never mind the moon or Mars – I suggest we go directly to Pluto.
These underground spaces have a constant temperature of about -4F – and probably warmer if you can find deeper ones. But -4F is workable – if you could seal and pressurize one of these domes, you could also heat it with solar or nuclear energy.
So we have the potential of pre-built ‘domes’ that can house millions of people existing just 3 days away from us, at a place we’ve already been to and could go back to for a tiny fraction of the cost of a Mars mission.
But why do it? What does the moon offer? Well, for one thing, vacuum and low gravity. The moon might be a great retirement destination. It’s close enough that a real tourist industry could develop. At 1/6 G, it might be possible to strap on wings and fly in a space like that. The opportunities for adventure and exciting new experiences would be endless.
Second, the lack of an atmosphere simplifies getting material to and from the moon. Mass drivers can be set up to send mass from the moon into space for free.
As for water, there is a LOT Of it on the moon. In 2010, a survey of 40 permanently-shadowed craters by the Chandrayaan-1 mission discovered an estimates 600 million metric tonnes of water. Even more interesting is the discovery that water may be produced on the moon through chemical reactions, and ‘migrate’ to permanently darkened regions. That means some of these lava tubes could be filled with water ice.
With unlimited water you can make rocket fuel and ship it into orbit, lowering the cost of space travel everywhere. That alone may have enough economic value to warrant building moon colonies. With water and energy you can make air.
John’s point about lack of nitrogen is well taken, although it’s possible we will find a lot more nitrogen in the poles. But even if not, shipping nitrogen to the moon to start a colony strikes me as a problem orders of magnitude lower than trying to terraform Mars.
The closeness of the moon also means you can move back to Earth if you want, that you can maintain constant communications with Earth, including internet connections (albeit with terrible latency…).
Mars is a pipe dream with today’s technology. The moon is feasible. And the early exploration of those lava tube skylights could be started now, and would be a hell of an adventure. Can you imagine watching machines or astronauts first lowered into a huge lava tube, and what it would be like to see the inside of a massive lunar cave? We could do an automated mission like that in a few years.
Wow – I had never heard of this. Very ingenious.
From John’s Wikipedia link (not to be confused with the slingshot maneuver):
Dan, those are vitamin-packed comments.
I admire Larry Koler’s grasp of explanations of orbital mechanics. Heck, I outright envy it. How about a new bumper sticker for Ricochet:
Our YECs Know More Science Than Your Honor Student
I say that not because it’s funny, but because it’s true.
Haven’t we been to Mars already?
This is a nit that bugs me, so I’m going to pick it. Obama actually said there are 60 states. He said he’d been to 57 states with one to go, plus Alaska and Hawaii. Not picking on you. It’s an Obama gaffe that people misinterpret.
Dejah Thoris. That’s why.
One of my recurring sci-fi fantasies involves bombarding the surfaces of Mars and/or the Moon* with water-ice comets or other bodies, thus making them much friendlier for human colonization. Can someone link a book or website or article that sketches out the engineering challenges involved?
*Note: introducing lots of water on the Moon would raise the albedo of the Moon (wouldn’t it?). (For all its apparent brightness in the sky, the Moon currently has the reflectivity of asphalt.) This would result in much brighter nighttime conditions on Earth, which would disrupt ecosystems. I am not recommending we screw around with introducing oceans on the Moon anytime soon.
Dang it, Dan, you are getting perilously close to an idea I’ve been sitting on for a sci-fi story. Don’t go stealing my ideas, buddy.
Be careful dropping information like that. AlGore and the democrats will have a UN sponsored global man made moon expulsion justice program ginned up for a couple trillion $’s to combat lunar expulsionology (is so a word, King Prawn says so).
Heinlein already hit that one, didn’t he?
The real one, or the one played by an over the hill porn star?
Eric Hines
Mars is “cool”. These days the Moon, as far as space-travel-sexiness goes, is like kissing your sister.
I don’t see how we would supply any of these places (Moon or Mars) with enough food to sustain a permanent colony. Food is heavy, so shipping it our from Earth to these places on a regular basis is very cost prohibitive. Growing the most basic of Earth foods like potatoes (as was done in The Martian) I also don’t think is very realistic, these plants need to be supplied with nitrates, phosphates, carbon dioxide, a lot of water, and sufficient sunlight. Now sunlight might seem free after all it is on Earth, but consider the Moon and Mars. On the moon the solar intensity should be similar to Earth, but the day-night cycle is 2 weeks or so. No crop plant will grow without two weeks of light. Artificial light will be a major source of power consumption. Plants need a lot of light, just ask your local pot growers. More specifically they need a full spectrum of light. LED and florescent lights are great at power conservation but they have a limited spectrum and don’t put out as many photons as a plant would like. Incandescent bulbs are actually better from the perspective of light spectrum, but they are terribly inefficient. Furthermore you would really need to keep plants growing on something like 100 to 150 watt light bulbs for at least 12 hours a day to drive good development. That is a lot of juice.
Continued.
No matter where you take your plants you can’t depend on the Sun. On the moon you will have long nights, on Mars the solar intensity will be greatly diminished making photosynthesis highly ineffective, the food yields will therefore be very low, to possibly none. So you have to supply your own light. Water is easy enough, but where will we get the nitrates and phosphates? On earth they are naturally found in the soil, thanks to microbes, but even the natural levels in the soil are insufficient for modern agriculture, so we supplement them with synthesized ones. Are we going to be shipping fertilizer into space? I don’t think so.
If you think we can make soil from what we find on either the Moon or Mars I would call you overly optimistic. The moon is basically all rock, soil is a composition of various clays, and organic matter. So the Moons surface is basically worthless in that respect. Might as well try to grow plants in pulverized concrete. I doubt Mars is much better though it may have some clay if it ever had liquid water on its surface. Still you aren’t going to be able to build up this complicated ecosystem that is soil. So you will probably be stuck with some sort of hydroponics contraption. What grows best on hydroponics though are leafy vegetables, which aren’t very carbohydrate rich, as compared to corn or potatoes. No civilization was ever built on lettuce.
Lastly there is the issue of gravity. Now gravity for animals is easy to ignore, we don’t depend upon it for our development, plant on the other hand do. Low gravity will effect plant growth rather drastically, especially root development. Basically in low gravity root systems may not develop fully. This in turn will effect the plants ability to take up nutrients, which will in turn lead to reduced yields.
The only thing I can think of that might get us what we need in terms of calories and easy gravity free growing is creating genetically modified single cellular algae that produce and store a lot of starch and amino acids, maybe some lipids. These can then be cultured and processed into some form of nutritional paste resembling this handy dandy product. Yes, if you clicked the link it is exactly what is sounds like. Minimal human growth media. I think people would survive on this. But making such happy algae is no small task of bio-engineering, and everything I said about water, sunlight, CO2, nitrates, phosphates, still applies.
I think people would go insane if all they had to eat was a nutrient rich protein shake.
So unless we find someway of getting things off of earth for less than 10000$ a kilogram we will never be able to make or sustain any large permanent settlement anywhere, because we won’t be able to feed it.
I am still immensely skeptical. Unlike making a settlement on Earth, where you can start by planting crops right away, on the Moon and Mars there will invariably be a long lag time to food production. This will have to be filled by supplies from Earth, and getting things off the Earth is hard and expensive. Can we really supply a Lunar outpost much less a Martian one with enough food for several years?
Basically either on the Moon or Mars food production is starting up from zero. I will have a lot more confidence that we can do this if anyone manages to create a self contained Earth-side green house farm, somewhere like Antarctica. Where you get the water, and sunlight for free (at least for a few months), but the temperature and soil are absent. Has anyone done that? Potted plants don’t count. You need to show you can grown enough human accessible calories to support half a dozen people indefinitely.
I haven’t read the comments. I’d like to respond to the OP. (I apologize if this has been covered already.)
When politicians talk about it, it’s to distract us from something else. They make grand pronouncements, and they’re later quietly abandoned. When it comes to space, ever since Kennedy, people take their cues from politicians, specifically presidents.
Why Mars?
Because nobody is really serious about the manned space program. If they were, the Moon is the only logical place to start. But they’re not, so we hear pie-in-the-sky nonsense about going to Mars.
Addendum:
I am 100% pro-space exploration. Please read my above tone as one of utter disgust with the last four decades of the US space program and what a waste it’s been.
I envision this as a gradual process. We would start by building a sample greenhouse inside a Lava Tube, feeding it energy from the surface, and trying to grow plants in lunar regolith under those conditions.
Eventually, you iterate what you’ve learned until you come up with a stable process that looks like it will scale. Then you bring in 6-10 people and try to do a ‘biosphere’ type project – self-contained living for six months, say. Of course, you have all the backups and safety systems there.
And so it goes. We expand as we find space, we learn exactly how much food crop we need, how much mass we have to import annually per person, then work to solve those problems. Pretty much like the history of any other new branch of technology.
But here’s where the moon is far superior to Mars: If we ever wants to have mastery of space engineering, we need to iterate. We need to fly a lot, so that we can learn from our successes and failures. That means lots of smaller missions, instead of a once-in–a-decade megamission.
We will be ready to go to Mars when we are so comfortable with setting up and using habitats off earth, producing food and recycling consumables, and a million other mundane acts of living that it becomes a routine with high levels of safety. And the fastest way to get to that point is to find something closer and faster but still rewarding.
Can Plants Grow on Mars and the Moon: A Growth Experiment on Mars and Moon Soil Simulants
The feasibility of either project is ultimately going to come down to launch costs. The problem with NASA’s approach is that it relies on a very large, very expensive rocket that must be thrown away after each mission. That make it too cost prohibitive to fly more than once every 2 or 3 years. That’s too slow to develop a launch rhythm that creates the best atmosphere for safety, and it’s too slow for an iterative learning process. Couple that with the inevitable delays and bloat that come from being at the whim of the idiots in Washington, and it gets worse.
That’s why SpaceX’s reusable rocket program is so important. I expect them to successfully soft land their boosters within a year or two, and that changes the game. Cost to orbit will drop by 80%. At that point, a lot of things become feasible.
Whatever we decide to do in space is currently irrelevant, because we can no longer make and execute any plans past the next election cycles. And there will always be another around the corner, and there are many other long term plans that need a higher priority than manned space exploration and colonization, such as sane fiscal policy, hardening our electrical grid, etc.
I agree with Valiuth and that the problem of growing enough food offworld is the greatest technical hurdle to extraterrestrial colonization. The other problems have solutions with existing technologies.
Creating a sustainable or very nearly sustainable closed ecosystem (that includes an expanding human population) with offworld resources would probably create tremendous spin-off technologies applicable to earth agriculture.
We would also need to have a great deal of experience with it before we could risk sending or birthing a large number of people offworld.
The problem I have, and hopefully doctors and biologists can shed some light, with “growing food” is the amount and nature of trace minerals and trace chemicals that Earth-type life, particularly us humans, have evolved to need in some sense in our metabolic biology.
I suspect that, as we go down the complexity chain of edible materials to the algae that was suggested earlier in the thread, we can get stuff to grow in, say, the Moon’s regolith. But algae isn’t going to conjure those trace minerals and chemicals out of the æther; if the stuff isn’t in the regolith, it won’t get into the algae, and us humans (and our cows and chickens and pecans and…) won’t be able to get the stuff into our metabolisms.
“The right food” isn’t a straightforward thing, either. To take a coarse example, the meat from corn-feed beef isn’t like the meat from range-/grass-fed beef in some important ways. There’s growing evidence that indicates that, while the former may be healthy enough for humans, it’s not as healthy as the latter.
If that stuff is, in fact, not in the regolith (which is chock full of oxygen, iron, aluminum, and a couple of other things. However, as anonymous has said, we really don’t know squat about what’s in the regolith), we’ll need a means of getting the stuff into the bottom of the food chain–into the “soil”–in sufficient quantity that the organisms higher up the food chain get the trace amounts they need.
Eric Hines
Algae cakes! James Lileks had something to say about that.