In certain corners of the astronautics community, there’s a real and substantial debate over whether to prioritize Mars or Luna when planning out the future of human spaceflight. There are good arguments on each side, but I think that neither side makes the correct case.
Luna is attractive because it is close. We know how to land on Luna; we’ve done it before. Building bases on Luna would offer the opportunity to really understand how humans live and operate in space over the long term. It would provide a test-bed for certain technologies that would enable more advanced missions to the planets. If things go wrong, it would be easier to get support from Earth, or to head home if need be.
The counter-argument put forth by the pro-Mars camp is that Luna is a very different world from Mars, and thus wouldn’t provide really all that much advantage for testing Mars-specific technologies. Life support systems on Luna would necessarily use a very closed loop; aside from some water deposits at the poles, astronauts would want to recycle as much as possible. Mars, on the other hand, has water and carbon dioxide and organic molecules in abundance. It offers much better options for building self-sufficient outposts.
There’s also disagreement about the efficacy of using Luna as a refueling stop, so to speak, en route to the Red Planet. From an orbital mechanics standpoint, it’s not a slam-dunk idea, but the argument in practice depends heavily on the specific logistics. In-situ fuel production might just make such a configuration worth it.
In any case, both camps miss the main question when it comes to long-term off-world development: where’s the money coming from?
While Mars is obviously the more attractive target for colonization, we are a very long way from building colonies on other celestial bodies, no matter how good of an idea it is. The reason is very simple: space colonization is an unspeakably expensive proposition. The off-world economy as it currently exists is entirely constructed around servicing needs on Earth, and there are no terrestrial markets which demand colonies on another planet.
I have yet to think of an economic need which a self-sustaining population on Mars would fulfill, that innovative strategies could not fulfill on Earth. Farming food on Mars? We can do hydroponics here. Running out of room to house people? We’re nowhere near that kind of population density. New legal environments to test out social engineering concepts? Seasteads and charter cities are way safer and less expensive. Climate change? Just tax carbon and build nuclear power plants, sheesh.
No one will front the money to build Mars colonies until there’s an economic incentive to do so. I see no such economic incentive. I would love to be wrong about this, because Mars is the best colonization target by far. But I don’t think I am.
Nevertheless, there are profits to be made in space.
There are needs on Earth which off-world industries can satisfy. Currently, most of the needs which we’re satisfying relate to information on or near Earth’s surface: passing data quickly between two points, or observing the location of moving vehicles, or watching the development of weather systems—things in that vein. There’s been a lot of discussion of space tourism, but that has yet to make any real money without piggybacking on government-funded flights. Scientific probes and the like are great, but largely a public service. They don’t represent the sort of self-sustaining economic sector that successful space colonization requires.
What self-sustaining options are there? Honestly, that’s very difficult to predict. Modeling the profitability of a venture depends heavily on the assumptions we make. How far will launch costs fall over the coming years? Will other space technologies follow suit? What will the tax and regulatory structure look like in twenty years?
Some things are simply impossible to know at this point: how materials behave in microgravity, what resources are available in space, and in what forms—and how much will everything cost? Will there need to be humans involved, or not? These are impossible to know without further investigation; basic research is, in many cases, a part of the capital investment. Publicly-funded space agencies have done a great deal in this area, but the private sector is going to have to carry some of its own weight before turning a profit.
We can still speculate, of course. I think in-space manufacturing and resources from space are potentially tremendous markets. That said, many people get these aspects wrong. For instance, many will point to the nominal value of precious metals in asteroids, ignoring the fact that introducing such quantities would immediately and permanently crash the market. In that particular regard, what’s far more interesting is the possibilities that open up when platinum, say, becomes cheaper than aluminum is now.
The real value of off-world industry will come in the things we can do in space that we can’t do on Earth. This includes all sort of material processes (though, of course, gravity makes a great many things easier), and the lack of environmental concerns. As the people of Earth demand an increasingly high standard of living and simultaneously a cleaner environment, I suspect that this may prove to be the ultimate driver of off-world industrialization. Again, though, speculation.
Towards that end, staying near Earth is much more attractive logistically than going all the way to Mars. Orbital space stations are preferable to Luna is preferable to asteroids. considerations eat up the profit margins, to the extent that off-world resource extraction has yet to enter even the demonstration phase. The cost of even basic space technology is currently prohibitive.
Those costs will fall, at least to some extent, but the basic logic remains. If all we need is microgravity, there’s little reason to go above low Earth orbit. If we desire some degree of gravity, Luna will probably do. Asteroids may be useful targets for mining, but I would need to see actual numbers before deciding whether to pursue particular resources on Earth, Luna, or smaller bodies.
Critically, space industrialization is different from space colonization. Developing an off-world economy is a pre-requisite for seeing a large, permanent population above the atmosphere.
Certainly astronauts can visit Luna and Mars. We might even establish permanent research bases. This, however, is a public-spirited endeavor. Governments may choose to pay for scientific missions to other planets; they will not front the costs of developing entire planets quite literally from the ground up. Whatever outputs space agencies may build, they will not be colonies. People won’t live there, the way that human populations have whenever establishing themselves in a new locality. There won’t be families and new businesses and the like, not for a long time.
Instead, we’re probably going to see many largely-automated operations, with minimal and possibly intermittent human presence. Over time, these will expand, and eventually we may see actual colonies in orbit and on Luna. But that will come only once there’s a profitable market for goods manufactured or processed in space. These industries will beget new markets, which may be satisfied by other off-world industries. At some point down the road, there very well may be demand which can be more profitably supplied from Mars than Earth (from a perspective, it’s easier to reach Luna from the surface of Mars than Cape Canaveral). But I think that it’s unrealistic to expect that to occur particularly soon.
As we push towards human settlement in space, our focus should therefore be the development of new industries and new technologies to enable and motivate working above the atmosphere. Between the two targets of Luna and Mars, the former clearly comes out ahead for this purpose. Proximity wins over hospitality, though many of the disadvantages Luna has as a world are significantly less serious in the context of production rather than settlement.
One day, our species will span three worlds. That day remains very far away. Rather than fixate on terraforming dreams, we should chart a course carried by the currents of economic necessity. With the correct regulatory environment and technological investments, we can begin building sustainable off-world industries in a realistic timescale. Such industries will carry us to the planets in the pursuit of profit—a far more reliable motivator than any humanitarian spirit from politicians.
That, I suspect, is what the future of space travel is going to come down to. Do we pursue an incremental strategy that eventually carries us to the ends of the Solar System, or do we wallow on this one planet, fantasizing of an amazing future no one has any incentive to hand us? Are we going to fixate on self-sustained colonies and settle for nothing less, or shall we go to Luna first, but not to live there?