What it Would Really Take to Get Humans to Mars

I vacillate between thinking of Elon Musk as a visionary and a Bond villain. (Can a man be both?) His futuristic visions arrive with suspiciously competent marketing. Electric cars are neat, but they’re only “green” in as much as they shift pollution to the electrical grid, done at a high marginal expense of putting big battery arrays into individual vehicles. As a sci-fi geek, I’m thrilled at his high-tech rockets. I also roll my eyes that we’re still relying on massive, contained explosions to get into orbit. What about massive airships which float gently to the edge of space, say more than 30 miles up, and then launch a craft from there via railrun? (Just as a sci-fi proposal to get craft into orbit without burning massive amounts of rocket fuel.)

Like a lot of people who are genuinely interested in the idea of long-term space travel and exploration, I probably have my eyes to the horizon, taking for granted that we will get to that level someday while being impatient  to see theoretical technology finally brought up into the big game. Even when I was young, I was more bored with the Space Shuttle than I was impressed. Partly this was because I didn’t want a ricketty, expensive shuttle. I wanted the Millennium Falcon. Now, obviously, the more I learned about science, the more I realized that the Millennium Falcon is a fantasy object, a totemistic item which cannot exist, but which we use a cipher for our imagination. But that reality aside, the fact remains is that we can do much, much better than what we have done. We won’t get Millennium Falcons. But we can do better than just using big rockets to get into orbit every time we need to do so.

My impatience with the large expense of fossil fuel just to get a single rocket to escape Earth only scratches the surface of my desideratum for space travel. There is, Musk marketing magic aside, no feasible plan to send humans to Mars except merely as a man-in-a-can, one-way stunt. I think that would be a tragic mistake to do.

First and foremost, there is a huge downside to getting humans to Mars just to prove we can do it. Any life-form from Earth which sets foot on another planet would bring, necessarily, billions of bacteria, viruses, and other flora and fauna, which would taint the research of looking for signs of life, or former life, on any planet. Even people desperate to get to Mars as a one-way trip would inevitably risk tainting future research by planting their bodies there.

Titan, Europa, and Mars all have the possibility of sustaining life or having once done so. It would be vitally important that sterilized mechanical arms sift through these environments before we plop our own bags of Earth-born protoplasm onto their surfaces. It would be un-ethical for any one human to bring their own personal cloud of billions of Earth-born microbes on to an alien surface. At least not without extreme scrutiny of the environment first to see if there is any native fauna. This scrutiny needs to be done by machines which we’ve only begun to develop.

The proven ability of humans to actually live and traverse in space has only barely edged beyond what we knew during the Apollo missions. The shuttle missions were two decades of spinning wheels in planetary orbit; burning through money and fossil fuel while hardly pushing the envelope for long-term space missions.


Mary Roach’s book Packing For Mars details the incredible difficulties humans face with even relatively local space travel. Zero-gravity is incredibly difficult for humans. Your blood doesn’t flow correctly, your digestion doesn’t work correctly, your bones leach calcium, your eyeballs swell. Even things we take for granted such as sweat evaporating, heat and exhaled carbon-dioxide moving away from our bodies, do not do so without gravity. Experiments on mice indicate that it may be impossible for mammals to get pregnant in zero-g.

Additionally, for all our faffing about during decades of building shuttles and space stations, we haven’t successfully built spaceborne habitats with any ability to sustain a living environment for long periods of time. We’ve built tiny stations which must have waste products removed, and food and air and fuel constantly replenished by rockets from Earth.

Humans have lived in space for long periods of time as games of endurance, akin to Lindbergh flying across the Atlantic or Scott at the North Pole. The persons managed to do it under extreme conditions, in extreme discomfort, and likely will have lifelong physical effects. We have not build a habitat that a normal person could live in for any amount of time other than treating it as an extreme sport and the type of thing done on a dare.

Astronauts have been highly selected, brave volunteers who chose to expose themselves to these possibly permanently debilitating conditions. They’ve had to be highly selected because we have yet to even attempt to build anything which would approximate anything like an environment suitable for humans to live with any sort of normalcy.

This isn’t even mentioning the massive doses of radiation which all astronauts have been exposed to. We have yet to perfect better shielding for any real space exploration. While it’s perfectly logical that we may yet do so, this is one of the major engineering projects which is both highly involved, and highly necessary, before we can even begin discussions of humans traveling the distance it would take to get to Mars.

The real goal for humans living in space needs to be a space-born structure, heavily shielded from radiation, which makes an effort towards sustaining a self-contained environment, artificial gravity, and the ability to move the craft (even slowly) beyond just being captured by orbital velocity. This means attempting something like a 3-kilometer wide wheel which spins at a velocity in order to create some kind of centrifugal artificial gravity, has some sort of ability to move, even slowly, and maybe has maybe the intervening wheel spokes full of algae and water in order to cycle waste products and produce fertilizer, fuel, and oxygen. This is my back-of-the-envelope suggestion for what NASA ought to be focusing on. It’s what commercial ventures will have to undertake as well if they want to beat others to colonize space.

The wheelship I reference above would be a huge undertaking, but as far as we know, it is feasible to attempt all this. We have to yet to find out how scaling up contained biospheres, solar sails, or centrifugal gravity would work, but testing all of them in functional spacecraft is preliminary to any plans for humans to land on other planets. Craft like this theoretical wheel could be a prototype for platforms to facilitate humans living in space for long periods of time.

Meanwhile, real efforts to push out into space require more advancements in robotics and material design. Highly articulated machines, abetted by better AI, could do the preliminary work of landing on planets and begin building long-term structures for human habitation. We have yet to revolutionize cheap carbon-fiber weaving, or fully develop machinery which could theoretically smelt, shape, and 3-D print construction material from, say, moon soil. But all of this is necessary to create the stepping-off point for humans being able to actually live beyond Earth. The prospect of constantly lifting off massive amounts of Earth material and supplies is incredibly expensive, and being able to repurpose the material found beyond our own planet is the key part of genuinely being able to explore space over ensuing generations.

The short-to-long term future of humans expanding through our solar system seems to ultimately rely on two main inevitabilities.

First, robotic forms, either as our inheritors our as our avatars, are going to be our foremost leading edge when exploring other worlds.

Second, biologically, we’ll either be finding better ways to replicate our own bisophere beyond our world, or genetically modify ourselves to better adapt to different gravity, radiation, temperature fluctuations, etc. All of which we’d have to endure with long term space exploration.

Almost certainly, humans will use all these different paths.

When humans expanded and colonized our own planet, we did all of these things. Humans adapted their bodies over generations as they spread out into different regions of the planet, creating slight differences which we unscientifically have categorized as races or ethnicities. Skin pigmentation changed to better adapt to the sun in different environments as humans wandered into different continents. Our layers of fat adjusted over time to temperature, as did density of bone or muscle, or the ability of our blood to carry oxygen at different elevations. All of this was genetic adaptation over the slow process of hundreds of thousands of years.

Our need to have better technology to live in new environments has always been part of the human story. There are very few environments on Earth in which naked humans could survive. All evidence points to humans wearing clothing and building tools from the earliest hints of homo-sapien cognition. We built tools to adapt to new surroundings, from the cro-magnon to the Internet age, from the atl-atl to air conditioning.

Humans didn’t simply fling themselves to Australia or Greenland and survive. They learned over time how to live with what was there. (And when environments like Greenland changed over time, they mostly became simply inhospitable to human habitation.) Humans avoided living in environments like the Sahara or Death Valley until relatively recently because the environment is so hostile to our needs for life. Even now, we only have little more than symbolic human colonization of Antarctica, which is a relative Eden compared to the cold, dead, distant, airless, radioactive, ⅓ gravity environment of Mars.

I’m as interested as anyone else at the prospect of moving beyond our home planet. It will be space stations as stepping stones, and better and badder-assed robotics to get us there. The idea of colonizing Mars is a wonderful fantasy which Elon Musk is selling to an eager public. It is just that right now — a fantasy. But the effort to actually, seriously, get us there, requires a lot less-sexy endeavors which are often quickly elided when discussing what needs to be done. Bring on the robots. Bring on the zeppelin orbital-craft launchers. Bring on the wheelships.