In my last post I speculated about how we might adapt ourselves to the environments of other planets rather than trying to terraform them or forever be confined to enclosed settlements and space suits. I used Mars as an example of an “earthlike” planet we might consider colonizing.

A Mars-type planet would be an easy challenge compared to others like Venus. The Venusian atmosphere is also mostly carbon dioxide but the air pressure at the surface is ninety times that of Earth, like being a thousand meters deep in the ocean. We know that fish and other creatures can exist at those depths, and some whales can dive even deeper for a time—so it’s not inconceivable that our bodies could be adapted for it (maybe even encouraged to grow a hard shell?) But again, we wouldn’t be breathing—air at that pressure is basically a fluid. We’d have to get oxygen and/or energy another way. And Venus is hot—hotter than Mercury—about 460 C at the surface. If there is any part that might be relatively hospitable to humans it would be the upper atmosphere, about fifty kilometers high, where the temperature and pressure are nearly Earth-normal. There are obstacles though: winds over 300 kilometers per hour and clouds full of sulphuric acid!

OK, so maybe Venus-like worlds will be beyond biological adaptations and require either full space suits or at least extensive mechanical adaptations.

Gas giant planets don’t hold much attraction as homes-away-from-home, but many of their moons might. With a tough enough skin and a metabolism that uses chemosynthesis instead of air-breathing, maybe we could survive in a near-vacuum, but it’s hard to imagine that we could ever adapt our bodies to temperatures that can freeze water as hard as granite. On Jupiter’s moon Europa, for example, the temperature at the equator (you know, the beach resort zone) averages about -160 C. Where there is a possibility of survival, however, is under the icy surface in an ocean of water. Someday we may create humans who can function as aquatic creatures, in which case our own planet’s oceans will provide a vast amount of space to explore and inhabit.

There’s a chance that we’ll discover planets elsewhere that are almost identical to Earth and already support life. In that event, our problem will be that some of the life, particularly microorganisms, could be utterly hostile to humans. Deadly germs or bacteria. Then we’ll need to either adapt our immune systems to cope with the pathogens, or adapt our whole bodies to co-exist with the alien organisms (although, to be accurate, we’ll be the aliens).

I haven’t even touched on the whole area of technological enhancements to the human body—turning us into partly-cybernetic organisms, or cyborgs. Maybe in another blog someday. And, of course, there are huge philosophical and ethical questions involved whenever the question of bio-engineered humans is raised. Is it too big a risk? If such genetic engineering had to occur at an early age or even at the fetal stage, could we make such decisions for our children? Most of all, how much can you change someone before they’re no longer human? We don’t mind the idea of fictional superheroes transformed by a radioactive spider bite or gamma radiation—the reality might evoke feelings that are quite different.

For now, I’m content to leave this as an exercise of the imagination, but the time will come when we achieve the capability for such things. I hope we’ll have resolved our questions about it by then.


In a recent post I mentioned that there are huge amounts of water elsewhere in the solar system—much more than actually exists on Earth. And when scientists assess the potential of other star systems to host life, the foremost yardstick they use is the presence of water, especially liquid water. Where there’s liquid water, there could be life that we would recognize. So a planet orbiting its sun in the so-called “Goldilocks zone” (not too hot, not too cold) might have liquid water and thus be capable of supporting life. Maybe.

This fairly narrow view isn’t so much based on the idea that we only want to meet aliens that look like us (as in most Star Trek episodes) but more because we want to visit places that will present the fewest obstacles to our survival there. Lots of oxygen in the air would be nice. Clean drinking water. Reasonable weather. Gravity that doesn’t make us feel like we’re wearing lead overcoats.

You’ve probably heard news stories about “earthlike” planets being discovered around other stars. That description usually only means that they’re rocky planets instead of gas giants, and they’re not frozen or roasting hot. That’s it. Everything else about them might be far different from Earth—we just don’t know because those planets are too far away. We do know about the planets in our own solar system, and by the above standards Mars would be considered earthlike, except a little cold. But we certainly can’t live there. At least, not yet.

For humans to survive on another planet—in this solar system or any other—there are three ways to do it. The ways that get the most attention are: 1) building habitats (even domed cities) that will protect us from the planet’s hostile elements and enclose a simulated Earth environment; and 2) change the planet’s entire ecosphere into a close approximation of Earth’s—what is called terraforming. Enclosed habitats will always be very restrictive and costly to expand, while terraforming some place like Mars would take thousands of years.

The third option is to change the human body itself in ways that will adapt us to the alien environment.

On Mars that would require quite a few changes. We know that people can adapt to colder climates (especially over a number of generations) but even Mars’ most hospitable climes would require genetic tweaking to rev up our metabolism, increase blood flow, and grow much thicker layers of insulating fat under our skin. We’d have to grow a tougher skin, too, with closable orifices—even skin pores and tear ducts—to prevent the low air pressure from boiling away our bodily fluids. These things aren’t inconceivable as we get better and better at gene splicing—we’d find organisms with those traits here on Earth (perhaps creatures that live in extreme environments) and splice the necessary genes onto our own genome. Even so, a few more mechanical implants might also be in order, like heating coils in our nostrils to warm our inhaled air!

Mars’ atmosphere is mostly carbon dioxide with very little oxygen, so to avoid the need to carry air with us we’d have to either re-engineer our body cells to use some energy source other than oxygen, or get assistance from something that can make the oxygen we need from CO2. Plant life uses photosynthesis to produce food energy from carbon dioxide and water using sunlight (but it’s slow). Creatures that live around deep-sea volcanic vents use chemosynthesis instead, getting their energy, not from sunlight, but from the oxidation of compounds like hydrogen sulphide gas. Giant tube worms, crabs, clams and others are filled with proteobacteria and archaea—some of the earliest life forms on the planet—which replace their usual digestive tracts of stomach, intestines etc. And we know many kinds of algae and bacteria that can produce oxygen from materials in their environment, including the bacteria Methylomirabilis oxyfera which extracts oxygen from nitrates in the river mud where it lives. Since our bodies already carry around hundreds of types of bacteria that help keep us alive, it’s not a huge stretch to believe that a few additional species might help us exist on other worlds.

Mars would be one of the easier planets for us to adapt to. And, of course, there’s the whole ethical question of whether or not we should tinker with the human body to that extent at all. But that topic will have to wait until my next post. In the meantime you can read some other people’s thoughts about this here, here and here.


Those of us who believe that humankind has a destiny among the stars are convinced that somehow, some day, a faster-than-light method of travel will be found. Warp speed. Jump ships. Convenient wormholes. Whatever will get us to other star systems and their planets in a reasonable amount of time. Physicists and mathematicians look at the formulae, pat us on the heads and say, “Good luck with that.”

The alternative is what became known in science and science fiction as “generation ships”: giant ark-like spacecraft meant to carry hundreds, or even thousands of people, many of whom might be born, live, and die while the ship is still in transit. The concept showed up in novels like Orphans of the Sky by Heinlein, The Songs of Distant Earth by Clarke, even TV shows like the early 70’s clunker The Starlost and parts of the movie WALL-E. After all, even optimistic estimates of near future technology place the travel time to the Centauri system, our nearest stellar neighbours, at more than a hundred years. The human lifespan is edging up to that figure, sure. But we wouldn’t launch a crew of babies, counting on them to build a colony at the end of the trip while in their final years of life. Other stars with potentially promising planets for colonization, like Gliese 581 and Gliese 667C are five times as far. So the spacecraft required would have to be self sufficient and support suitable populations for fifteen to twenty generations.

One of the popular arguments against such a project is that, by the time the first ships reached their goal, technological improvements on Earth would have produced faster ships that would have passed the original colonists and rendered them obsolete. Who’d want to take that risk?

Obviously there are a lot more problems with the concept than just technical ones. What’s the attraction in setting out for the stars knowing you’ll die in space before actually getting anywhere? What would give purpose to the lives of all of those people in the centuries between stops, and what guarantee could there be that they wouldn’t develop completely different priorities along the way, utterly changing the mission? They might become apathetic with no challenges to overcome, or turn to war amongst themselves because of the pressures of confinement and boredom. They might evolve in ways we can’t predict (especially if the ship isn’t completely shielded from cosmic radiation). A lot can happen in a few hundred years. Would such children of space even be recognizable as human by the time they got to their destination?

Still, if there were to be a suitable type of human being for such a long journey in a big tin can, they’d have to be people who are perfectly content with something like an urban environment, never seeing natural settings larger than an inner city park. They’d probably need to be easily occupied by non-physical activity, especially diversions generated by computer—as satisfied with virtual experiences as the real thing. It might help if they’re not overly ambitious, so they don’t get into conflict over things like leadership. Content to spend their time in smallish spaces, interacting in less personal ways, since large gathering areas would be at a premium.

Hmmm. Is it just me, or does that sound a lot like the millennial generation?

Maybe the generation ship idea isn’t dead. It was just waiting for the right humans to come along.

Space Colonization Must Become More Than Science Fiction

Years ago I read an inspiring book called The Millennial Project: Colonizing the Galaxy in Eight Easy Steps by Marshall T. Savage originally published in 1992. The title wasn’t frivolous—the second edition, in 1994, included an introduction by science fiction legend Arthur C. Clarke. In great detail, Savage laid out eight practical steps for humanity to take to reach the stars, beginning with ocean surface colonies that would produce enough edible algae and other food products to end world hunger while they also used temperature differentials in the deep ocean to generate the electricity required for spacecraft launchers. The launcher he envisioned would use a long track and catapult system to fling transports into the sky, while giant ground-based lasers would power them the rest of the way to space (eliminating the need for the transports to have their own engines—reducing the cost of launching materials from Earth’s surface into space is probably the largest hurdle of all in space exploration). The remaining steps involved bubble colonies in Earth orbit, domed cities on the Moon, Mars terraformed to become habitable, asteroids mined and transformed to not only provide raw materials but also harness the power of the sun much more efficiently, and finally an expansion into interstellar space. Savage wasn’t just dreaming—in 1987 he’d formed something called the First Millennial Foundation to get the ball rolling, first with baby steps like a test aquatic colony/theme park in the Caribbean. Progress was slow.

Jump ahead to 2011: the First Millennial Foundation is now called the “Living Universe Foundation” and Marshall Savage has apparently permanently retired from any association with the concepts he originated. But the dream lives on. Many other possible technologies have been proposed to carry out Savage’s basic eight steps, and discussions continue (though, perhaps, not much concrete progress). On other fronts, there is an International Space Station in orbit, involving multi-national cooperation. The United States government has made announcements about returning to the Moon and then going to Mars—no longer stunts motivated by a political space race, but hopefully true research-based missions. This past Saturday NASA space probe Dawn entered into orbit around the asteroid Vesta, the first man-made object to orbit a body in the asteroid belt. But within the past decade NASA’s NEAR Shoemaker probe landed on the asteroid Eros, and the Hayabusa probe from Japan collected samples from the asteroid Itokawa. NASA has plans for a mission in 2016 to another near-Earth asteroid that has a small chance of one day threatening the Earth. These aren’t stunt missions either, but have to be considered as first steps toward someday making use of the asteroids in practical ways.

For now, human space travel remains horrendously expensive and dangerous, so we need pretty strong motivation to make it happen. If population pressure on one hand, and the benefits of space research on the other aren’t collectively enough, we should look at Marshall Savage’s original argument:

All intelligent life on Earth could be wiped out in a single cosmic catastrophe, whether by a mammoth asteroid strike, a genetic experiment gone-wrong, or any number of doomsday scenarios that are no less plausible because of their dire consequences. We know it can happen—there have been half-a-dozen mass extinction events in Earth’s history. And, for all our wishes, we still have no evidence that intelligent life exists anywhere else in the universe. Humankind may be all there is—all of the universe’s “eggs” in one “basket”. Until we know otherwise, we have a responsibility to preserve sentient life by taking it beyond this fragile place where it could be annihilated at one stroke.

Maybe that’s still too abstract for most people looking over their tax statements. Maybe the idea of cheaper materials or medicines is more appealing. Either way, space colonization can’t remain the stuff of science fiction. We dare not let it.