WHAT'S THE BEST DESIGN FOR A SPACE COLONY?

One day we’ll want a place humans can live beyond Earth. Mars and a number of the moons of the gas giants are prime contenders because they offer lots of space and many of the physical resources we’ll need right there—minerals and important gases locked up in ice or rock. Still, there’s a good chance that our first colonies beyond the atmosphere won’t be anchored to anything big and solid at all. They’ll probably be air-breathing environments floating free in the space between the planets. One of the five Lagrangian points, where the gravity of the Earth and the Moon are in balance, would be a good choice because once placed there, the colony would stay put. It would also be relatively close for purposes of supply, communication and, in the worst case, escape back to Earth.

Though we’ll probably place small-scale habitats in one of those spots to continue learning all we can about space living, I have a feeling that the first real colony of any size outside the Earth will be somewhere else. Like the center of a hollowed-out asteroid.

It just makes sense. We’ll be digging out the asteroid anyway, mining it for metals and anything else we can find. Depending on which rock we pick, it will probably have many of the valuable elements we’d find on a planet without the difficulties caused by planet-scale gravity. Plus man-made hollows inside a metallic rock will have plenty of natural radiation shielding. You can’t overestimate the importance of that outside Earth’s protective magnetic field. There would be drawbacks, though, including the great distance to the asteroids, the complete lack of gravity, and the difficulty of providing good lighting inside a rock.

In his inspirational book from the early 1990’s called The Millennial Project, Marshall T. Savage suggested that the best model for a space colony would be a clear giant bubble with smaller bubbles nested inside. Nice and simple. The outer bubble wall would actually be a double membrane with five meters’ thickness of water between the layers, which would allow sunlight through but block most harmful radiation. As with a hollow asteroid, though, there wouldn’t be any gravity, and we know that human muscles, bones, and organs quickly deteriorate without it. Savage believed this could be solved through a combination of electro-stimulation and exercise in special facilities spun at high speed to simulate gravity, but I have my doubts. A rigorous exercise routine helps the astronauts on the International Space Station, yet they still have to undergo months of rehabilitation when they return to Earth. Even if future space colonists never return to Earth, there are indications that microgravity over long periods of time will cause health problems.

Several concepts for space colonies are designed to spin to produce simulated gravity on their inner surfaces thanks to centripetal force (here’s a great page showing the most popular designs). The Stanford Torus is like a giant wheel, perhaps with one or more large mirrors placed nearby to reflect sunlight into the interior. In the movie Elysium the colony of this design had no roof, so shuttle craft could easily come and go. But there was no radiation protection at all, so it would only be feasible within the Earth’s magnetic field. With the Bernal Sphere concept, areas near the equator would have the highest gravity but it would weaken toward the poles, so there’d likely be a fat stripe of inhabited area with windows near one or both ends to let sunlight in. That’s a lot of mass to spin up considering so much of the surface territory would still have insufficient gravity. The O’Neill Cylinder might be the best design of the three: a large cylinder spinning on its long axis, with lengthwise sections of land area alternating with window strips to provide sunlight (actually O’Neill suggested pairs of cylinders close to each other rotating in opposite directions for reasons of physics I won’t get into here). Unless Scotty comes back from the future to give us the formula for transparent aluminum, like in the fourth Star Trek movie, the windows in the Bernal Sphere and O’Neill Cylinder would require a lot of glass or polymer, and all three of the above designs would probably still be deficient when it comes to radiation shielding.

Here’s my thought: What about using a giant bubble full of air of the kind suggested by Marshall T. Savage, but with an O’Neill cylinder spinning inside it? You’d get the radiation protection of the water (which would let you get away with thinner walls in the cylinder), lots of light, and the extra space in the bubble could be used for zero-g manufacturing and the growing of food crops that don’t mind microgravity. I realize that a wide-open wheel or cylinder wouldn’t work because of high-wind effects from the structure’s spin, but with sharply tapered ends and baffles to break up the flow of air, it should still be possible to come and go from the cylinder habitat into the rest of the bubble. Wind effects would also be less if we settled for something lower than full Earth gravity, thus allowing a slower rate of spin.

What do you think? Problems with friction effects? Static electricity? Give me your thoughts, I’d love to hear them.

It’s by playing around with such concepts that we’ll ultimately find the best solution.

SOUNDS LIKE WE'RE NOISY INTRUDERS IN OUR OCEANS

If you’ve ever explored meditation or been coached on how to ease anxiety, you’ve probably been told to picture a calm ocean view, or maybe even what it’s like to be under the water. You can buy recordings of gentle surf or underwater sounds to help you sleep. We tend to think of the ocean as a quiet place, and it must be especially quiet at the bottom of all that water, right?

Not so. Last July scientists from the National Oceanic and Atmospheric Administration in the US, Oregon State University, and the U.S. Coast Guard used a titanium-shielded microphone to record sound at the bottom of the Challenger Deep, the deepest point of the world’s oceans, eleven kilometres below the surface. The equipment picked up noise from faraway earthquakes, a typhoon that passed overhead, and even the propellers of a passing cargo ship—from eleven kilometres below! Of course, we already knew that whale song can travel vast distances across the oceans, too. Salt water is just a terrific medium for sound waves to travel through, which is probably why whales, dolphins, and a number of other creatures use sound to navigate the sea as well as bringing and keeping their social groups together.

The thing is, we humans aren’t the shy and retiring type. To be honest, we can be pretty loud. And that goes for the things we do in the world’s oceans, especially activities like deep drilling for oil and, soon, even louder seismological exploration to find deposits of oil. It doesn’t take a marine biologist to figure out that the noises we make will be disruptive to marine life over a huge area. Not just the dolphins and whales that use echolocation, but even the small creatures of the sea bed that are responsible for stirring up nutrients from the sea floor that other species need, and even provide dinner themselves for larger predators. Some marine researchers from the UK studied how loud human noises affected Manila clams, brittle stars, and small lobsters called langoustines. The noises made the lobsters stop making their burrows and the clams to shut themselves up tight as a…well, clam. You’ll know how they felt if you’ve ever had a construction company doing roadwork in your neighbourhood, or suffered through a blasting crew using dynamite to get rid of some inconvenient rock. The difference is that we expect to get some benefit from noisy projects like that—lobsters and clams don’t. Worse, we don’t yet know whether sea creatures recover from such disruptions or if there might be serious long-term damage to some species.

Something else could also be compounding the process. The huge amounts of carbon we keep throwing into the atmosphere isn’t just affecting climate, it’s also making the oceans more acidic. There have been concerns that more acidic seawater not only affects creatures that use sound for their survival (like the so-called “snapping shrimp”) but might actually pass sound waves even better, creating a louder ocean. That opinion isn’t held by everyone (see this study from the Woods Hole Oceanographic Institution) but the possibility means a lot more study should be done before we do damage we can’t undo.

What’s the science fiction angle on this? Well, living and working in undersea cities and factory installations has been an SF trope for years, and though we’ve only taken baby steps along that path so far, the depletion of land resources means there’s a good chance we’ll turn to the sea for a lot more than just oil in the coming centuries. Farther down the road, it’s even possible that we’ll make a presence for ourselves on celestial bodies like Jupiter’s moons Europa and Ganymede, or the Saturnian moon Enceladus., which are thought to have oceans of their own, maybe including forms of life. So while we’re learning ways to cut back on our other forms of pollution, let’s make sure we don’t ignore the sound pollution that could be just as damaging in its way. That’s just being good citizens of our planet and our solar system.

You know those neighbours who drive down the street blaring a hip hop bass line that vibrates your windows, and throw loud pool parties until 3:00 in the morning every summer weekend? We don’t want to be them.

THE MARS DILEMMA

This NASA video shows a concept animation of how one proposed Exploration Zone on Mars might work.

An excellent new article in Scientific American describes a meeting last October that gathered together dozens of the world’s most committed proponents of a manned mission to Mars. They hoped to be able to choose the landing site for the NASA Mars mission planned for twenty years from now, or at least come up with a shortlist. They didn’t.

There are a huge number of important factors to consider in the selection: they need a landing site that’s not too high in elevation (or the thin air will hamper the use of a parachute) and not too low (thicker air will hold too much dust kicked up during the rocket landing and cause problems);  a site close to the poles will be too cold and get too little sunlight, plus the rotation speed of the planet near the equator gives an extra boost to a departing spacecraft for the trip home. Producing rocket fuel for the return trip (from water) is essential—some places it would have to be processed from the soil using heat, or squeezed from rocks; places farther north or south likely have groundwater or ice under the surface, but they have disadvantages mentioned above. Areas already studied by the Mars rovers and other craft are well-known, with lots of data gathered over the years, but there’s something to be said for exploring new territory too. The Scientific American article covers all of those issues very well.

But one aspect of the Mars discussion might be even more of a roadblock than the selection of a landing site—the dilemma about microorganisms.

If there is some form of life on Mars—and answering that question is one of the main reasons for going there—there’s the risk that astronaut explorers will disturb some soil or rock, or thaw some ice, and release organisms native to that world which could find their way inside the habitat, maybe inside the astronauts themselves, and eventually back to Earth. It’s unlikely that precautions and decontamination measures would be 100% successful in preventing that, and there’s no way to know what kind of risk such life might pose to forms of life here on Earth. An alien ebola for which our immune systems have no defence? That’s an alarmist view, but not impossible.

Then there’s the other side of the coin: protecting Mars from contamination by us.

The United Nations Outer Space Treaty of 1967 forbids the harmful contamination of celestial bodies. Every spacecraft that goes to Mars has to undergo (and survive) rigorous sterilization procedures, which accounts for a substantial part of the costs of such craft. And that’s just metal and circuits—what about living bodies? Some researchers claim that the human body supports ten times as many bacterial hitchhikers inside and outside than the number of the body’s own cells. How can we possibly be sure of not leaving some of those bacteria behind on Mars? If the planet is utterly barren, the risk that our Earth bacteria might survive and spread might not seem like a severe consequence (except for violating the space treaty). But what if there is life on Mars? It will probably be in the form of microorganisms inhabiting the subsurface ice and damp soil, managing to survive under very challenging conditions. There’s a significant chance that the Earth bacteria we unleash could be deadly to Mars life outright or simply provide too much competition for scant resources.

We might discover the first known form of life elsewhere in the universe, only to find that our explorations have condemned that life form to death.

There’s an outside chance that we could dodge these problems with one very carefully regulated visit to the Red Planet. There’s no chance at all that we can ignore them if we ever establish permanent habitations there. So before we ever colonize other celestial bodies, we’ll have to decide whether it will be a one-way trip for the colonists (to prevent the contamination of Earth) and whether or not we have the right to spread our own form of contamination throughout space.

If you’ve read many of my blog posts you’ll know that I think it’s critically important for humanity to establish a presence beyond Earth—our small planet is just too fragile, and we’re too vulnerable here—but it may be that we’ll have to confine our migration to places that are unquestionably devoid of life.

On one hand we’d love to know that we’re not alone—that life has arisen elsewhere in the universe, but if it has, we may have to protect it from ourselves by staying away.

A dilemma indeed.