The moon is a destination, not a stepping stone.
Space policy in the United States continues to approach monomaniacal levels of emphasis on the red planet. Whether its Charles Bolden describing Orion EFT-1 as “the start of the Mars era” or Elon Musk planning to live out his last days on Mars, the tacit assumption of Mars as the ultimate destination for humans pervades mission planning.
The apparent inevitability of Mars seems not to be based on little more than mental inertia. Being a species that originated on a planet, it was only natural to think inside the box at first. We need to consider other options.
As an object of scientific study Mars’ ever-diminishing prospects for present life make it less and less enticing than the terrae incongnitae where life might be found at Titan, Triton, Enceladus, Europa, or even Io. As a home for human life, Mars’ potential is overshadowed by Earth’s moon.
Astronaut Chris Hadfield has called for a moon-first strategy for the simple reason that technologies for Mars are not mature. This in itself is entirely true. Many essential technologies for Mars have yet to leave the drawing board. The Orion capsule is not for the #JourneyToMars, it’s a vehicle for returning to Earth from the moon. The International Space Station’s ECLSS is the state of the art in life support, but still not prepared to operate without the possibility of evacuation. A radiation-shielded deep space habitat, large solar-electric propulsion module, or Mars lander remains entirely conceptual. As it stands, we can’t go to Mars. Equally pressing is whether we should.
Mars is not useful. The tenuous atmosphere and weak magnetosphere of Mars are of token value to survival. Humans can not survive on Mars — just survive inside a space station while that space station happens to be stuck on the surface of Mars. Given you’d be living in a station regardless, that’s not the best place for one.
The immediate challenges of space survival are chiefly matters of resources and radiation. Mars is one of the less compelling objects in the solar system in terms of the solutions it can offer to these problems. Getting to Mars implies already mastering radiation shielding and a mostly closed-loop artificial ecosystem for water, oxygen, and carbon dioxide. The wisps of carbon dioxide and water ice at Mars would allow a crew to top up and even turn some into fuel for the return journey, but don’t in themselves justify the trip. The same electrolysis and Sabatier processes could be carried out on resources from the moon, Ceres, Phobos, Deimos, comets, or asteroids — without dealing with Mars’ comparatively high surface gravity and famous “Seven Minutes of Terror” entry conditions.
Longer term colonies will want ample nitrites and 1g centrifugal habitats, access to which would be hindered rather than aided by the atmosphere and gravity well of Mars. Any prospects for terraforming are orders of magnitude more ambitious than even colonization, so not worth considering in present planning.
This is not to say that humans should never land on Mars. I hope they do. Let’s just be clear that it will be a mostly symbolic gesture. As Apollo proved, planting flags does not pave the way for permanent habitation. At this juncture, every crewed mission should be judged on what it does to enable permanent human presence. It’s the commercial crew program that points the way, where the needs of ISS create a market to be filled. The next step is economic trade entirely in space, rather than delivered from Earth. That will happen more easily along paths that are energetically cheap, such as between Ceres and an Earth-Moon libration point, than under a model fully directed towards shipping material down the Mars gravity well.
So what does the moon have to offer? Rather than being a place to become “bogged down” as Mr. Aldrin fears, it holds key resources for human habitation and space industry. The ESA has shown itself to be particularly savvy to the potential of the moon in recent videos:
Aluminum and oxygen can be extracted from the regolith. The southern pole has substantial water ice and nearly continuous sunlight for solar power. Many have proposed to use these resources to create hydrolox or ALICE fuel, which would be an accessible early role for the moon in a space economy. Ultimately though, there are even better things to do with the moon than make fuel to leave the moon.
Regolith can be combined with water to make “lunarcrete”, an effective building material that resists micrometeoroids, temperature fluctuation and galactic cosmic rays. Aluminum and silicates from the regolith can be used in other construction materials as well, for lunar habitats or spacecraft.
Photovoltaic cells could viably be produced from lunar materials. Renowned former flight director Chris Kraft has called for solar panel factories on the moon to provide power to Earth. That may not be the best course of action with respect to the radiation balance of the Earth, but the energy could certainly be put to use towards spacecraft and further industrial enterprise on the moon.
The particular geology of the Imbrium basin on the moon’s near side causes a concentration of thorium, phosphorus, and rare earth elements. This thorium (and lesser amounts of uranium) may represent the most accessible low-gravity source of fissile material in the solar system. Concerns about proliferation or environmental contamination have always hampered the use of nuclear power in space, but processing nuclear material from ore to Watts entirely on the moon could be the ultimate answer to NIMBY concerns. Phosphorus is an essential input to agriculture on and off the Earth. Rare earth elements could be used in magnets and superconductors with applications in electric propulsion and radiation deflection. Some may even be worth exporting to Earth.
In short, the possibilities on the Moon for trade, and if need be rescue from Earth, provide the means and the motive that Mars is lacking. It’s time to retire the #JourneyToMars.