The Space Reviewin association with SpaceNews

Illustration of astronauts on Mars
In their search for evidence of life, could future astronauts on Mars do more harm than good? (credit: Pat Rawlings/SAIC for NASA)

The Mars train wreck

Before it even gets underway, human Mars exploration is headed for a political train wreck. The likelihood of trouble is so great that advocates for human exploration of the Solar System probably should look elsewhere—toward a return to Earth’s Moon or asteroid mining expeditions. The problem is life, especially if we find it, but even if we don’t.

No matter how carefully humanity explores Mars, we will never be able to say with certainty that the planet is sterile. That creates immense political problems for anyone planning even one human flight to Mars, much less attempts to colonize the world.

The political reality is that human Mars exploration will be expensive and difficult, yet it has limited popular appeal. Getting such a mission underway will require the active cooperation of every involved constituency and the tacit acceptance of most others. Even privately funded missions—which, following Robert Zubrin’s “Mars Direct” ideas, are at least conceivable—would have to avoid much active opposition.

Unfortunately, political opposition is likely to be both active and powerful. The most surprising opponents may be the group one would expect to most strongly advocate human Mars exploration: the Mars scientists themselves.

I first started thinking about this issue after 2001’s Mars Society Convention near San Francisco. Even at that venue, a number of individuals expressed serious reservations about Mr. Zubrin’s ideas for unrestrained “living off the land” and the possible impact to native ecosystems. One scientist, who has actively supported human Mars exploration for many years, argued that it should be done the same way that humanity explores Antarctica.

He argued that scientists must always be prepared to “back out” and leave a pristine natural environment in the event that life is found. There is little point in discovering life on Mars if we immediately destroy it with terrestrial contamination. Any Martian life should be left alone to pursue its own destiny.

The most surprising opponents may be the group one would expect to most strongly advocate human Mars exploration: the Mars scientists themselves.

Unfortunately, a “back-out” strategy would drastically increase the financial cost—and thus the political difficulty—of a human Mars expedition. If explorers could not mine the regolith for local resources, most supplies would have to be delivered from Earth at almost inconceivable expense. Government funded missions would become much more difficult to approve and privately funded flights effectively impossible. Worse, by explicitly making colonization unacceptable, such a strategy would remove one of the strongest motivations for sending human beings to Mars.

Scientists are not the only ones who are likely to oppose human Mars exploration. Since a native ecology is possible, environmentalists may be expected to campaign against any contamination of the Martian environment, especially if it involves nuclear power. Fear of back contamination of Earth by any Martian pathogens will motivate many opponents.

Most likely, such fears are moot. Terrestrial organisms have already been delivered to Mars on inadequately sterilized spacecraft components, although they almost certainly could not survive on today’s heavily oxidized Martian surface. The slow but steady rain of large meteors splashes rocks, and possibly hardy microorganisms from under the ground, between Mars and Earth all the time. Recent discoveries suggest the possibility of a Solar System-wide natural ecology with the constant exchange of biological materials amongst the planets. Such arguments will cut little ice with many opponents, who will argue that even a tiny risk is too great.

If I am right that human Mars missions are politically impractical, where should advocates for human expansion into the Solar System look? There’s always Earth’s moon, which has the decided advantage of being close and inexpensive. Unfortunately, it has few of the readily accessible resources required to support human beings. Nor are there obvious ways to easily generate high-value items that can be traded for terrestrial resources.

Few organizations will care about, or even pay attention to, repeated human flights to nearby asteroids.

There is another group of practical destinations. With rich resources of volatiles and carbon compounds, living off the land, at least in part, should be practical. High-value commodities like heavy metals may be mined to trade for supplies and manufactured goods from Earth. Hydrogen and oxygen can be marketed to other space facilities. Most importantly, although these bodies are truly an alien environment for primates evolved to live on a relatively large world, these locations are among the least expensive places to get to of any in the Solar System.

They are, of course, the Solar System’s small bodies, especially Earth-approaching asteroids. Intriguingly, this class of worlds includes the Martian moons, from which fully reversable Mars missions could ultimately be staged.

The technological requirements and likely costs are low enough that individual entrepreneurs might even finance the first Earth-approaching asteroid missions. After a few economically successful bases are established, each flight to another body would be a small, incremental step beyond the last. No government-financed crash programs are required. Unlike Mars, the political costs are likely to be low: few organizations will care about, or even pay attention to, repeated human flights to nearby asteroids.

Once humanity learns to live off the land on small bodies, the whole Solar System opens up to exploration and endeavor. Our star system is chock full of asteroids and comets, in every conceivable orbit and location. Just like the Polynesians hopping from island to island across the Pacific, humanity could push from the inner Solar System, to the Saturnian moons, to the Kuiper Belt of carbon-rich icy bodies beyond Neptune, even into the Oort cloud—and, depending on the population of bodies in interstellar space, maybe to the stars.

Someday, humanity will go to Mars. For now, we should look closer to home, and start a process that potentially could, over thousands of years, bootstrap human colonists deep into the galaxy.