I was in grade school when Sputnik went up, junior high when Alan Shepard first flew suborbitally, and college when Neil Armstrong stepped out on the Moon. So I grew up believing we would have an actual presence in space—be a space faring-people. That’s one of the reasons I started reading science fiction and became a science fiction writer.
In the 1970s we retreated from the Moon and instead of long-range rockets built the Space Shuttle, essentially a vastly expensive truck to low earth orbit. So I thought we would be gathering our strength, learning the ways of space, and building an orbital presence. But one space station, poorly funded and still mostly a science experiment, is not much of presence, and now the Shuttle is gone.
My hope fades, although it still glimmers a bit with the commercial efforts of companies like SpaceX and Virgin Galactic. I have given two young people of my acquaintance who have scientific minds this challenge: “Get us off this fxxxing rock.” Space probes are nice. Space probes are cool. But if we don’t go out there and establish a presence, we’ll never actually use space or be able to defend ourselves. When the next big rock comes along, we’ll be the new dinosaurs. When the first visitors finally come, we’ll just be part of the flora and fauna, a curious form of talking monkey, but ultimately expendable. We have to get up there to establish our right to live in this neighborhood. It’s where we go from here. It’s what intelligent beings are meant to do.
But the next steps will be hard. If all we wanted was more real estate, a place to put our growing population, it would be cheaper and easier to build underground cities or domes on the ocean floor. Orbiting space stations and O’Neill colonies1 are expensive. You have to lift every part of a facility like the International Space Station from the surface of the Earth. You could also get raw materials like silicates for cement and oxygen and metal ores for structural framing by mining the asteroids or the Moon, but in either case you would already need a healthy presence in these places to undertake such projects. Compared to these structures, it would be several orders of magnitude cheaper to build a five-star hotel, complete with Olympic swimming pool and tennis courts, on the summit of Mount Everest. The logistics of construction and supply would be a lot simpler, too.
Logistics, or how to get there. … Right now, everybody who goes above atmosphere travels by some form of chemical rocket. It may burn solid fuel or a combination of liquid oxygen and liquid hydrogen, but essentially the motor is harnessing a controlled explosion. These vehicles are not like your family car or Flash Gordon’s rocket, where you just fill up the tank and go. It’s more like firing a bullet: a lot of manufacturing to prepare it, a flash and bang to get your boost, and then you’re sitting at your destination with a naked capsule or payload and a litter of spent shell casings stretching out behind you. Sure, the Space Shuttle was sold as being reusable, but it still had to be stripped down and practically rebuilt for every flight.
We have other ideas for spaceship motors: mass drivers, electromagnetic slingshots, ion drives, and fusion reactions, among the things we think we understand; and antigravity, warp drive, and wormholes among the things we can only dream about. But right now, we’re stuck with chemical motors. They will get you up to orbit, and with a boost from there you can visit the Moon or inner planets and, with a lot of planning and a narrow margin for failure, come back. Touring the outer planets is a one-way trip on built-up momentum, as is any excursion beyond the solar system. As far as ship technology goes, we’re in the same situation as a 15th-century sailor who knows about caulked planks and canvas sails. You can tell him about steel hulls, steam turbines, radar, sonar, satellite navigation, hydrofoils, and hovercraft. He’ll certainly want those things, but they will take generations of hard scientific work and the solution of many incidental problems in chemistry and physics to achieve.
Even if we had better drive systems, where would we go? Explorers like da Gama, Columbus, Drake, Shepard, and Armstrong will put up with huge risks and the possibility of failure to discover new lands. Settlers are willing to put up with a certain amount of hardship and uncertainty, but their hope of surviving and prospering must outweigh the troubles and frustrations they leave behind in the mother country. People who are living a good life full of family, friends, familiar places, and favorite pastimes in one country need a powerful incentive to pick up and move overseas, let alone to the Moon or Mars.
The Moon is a rock. We might find water frozen in polar craters and mine silicates for their oxygen. We would have to build underground to avoid being bathed in cosmic rays, solar flares, and ionizing radiation—not to mention that the surface is in total vacuum and alternately oven-bakes when the sun shines and deep-freezes when the sun’s over the horizon. A colonist would never see another tree, unless he planted one under a dome, and not see much of a horizon unless he suited up and went outside. Until a critical mass of colonists, infrastructure, and self-supporting technology grew up—most of which we can imagine but not begin to specify or build—the first settlers would depend entirely on shipments from Earth. That would put them at the whim of government budgets or commercial contracts under the control of far-off citizens or suppliers. Given the history of funding space exploration and the amount of lip service we regularly pay to humanitarian efforts, that’s a slender line to hang your life on.
Mars is only slightly better. Like the Moon, it’s too small to hold much atmosphere. Opening a window on Mars is like opening one on an aircraft flying at 115,000 feet. In the laboratory, you’d call it a high-grade vacuum. And the composition is 95 percent carbon dioxide, the only gas heavy enough not to bounce around and escape the surface. Mars is also bathed in radiation because it has no magnetosphere, the magnetic flux which surrounds the Earth and is generated by the convection of molten iron in our core. Whether Mars’s core is stone-cold dead or just strangely inactive is open to discovery, but the planet’s current state is that of being geologically and magnetically dead.
Venus is more likely. It’s about the same size as Earth and, although closer to the Sun, is still within the habitable zone. Venus has a thick atmosphere that’s about 96 percent carbon dioxide and the rest nitrogen. The pressure is ninety times that of Earth’s atmosphere at sea level.2 Unlike Earth, however, where a malleable crust rent by volcanoes and plate tectonics allows for release of energy from the core, radar studies of the surface of Venus suggest it is very young with few asteroid craters. The crust appears to be thick and rigid, retain heat, and allow that heat to build up until the whole surface simply melts, subsides, and reforms. Living on Venus might be like living on the downhill slope of an active volcano.
We can dream of ways to “terraform” such planets. Since the problem with the Moon and Mars is lack of mass—and we just don’t have ways to artificially build up gravity yet, if we ever do figure it out—these bodies will be the last to be made like Earth. Venus is a more tractable problem, if we could think of ways to stabilize the heat exchange in the crust, thin out the atmosphere, and pump in something like the eighty percent nitrogen, twenty percent oxygen that we’d rather breathe. Terraforming the moons of Jupiter and Saturn present similar problems.3
But until we learn a whole lot more in terms of science and engineering—and some of it can only be learned by going there, encountering the problems one at a time, and solving them—the amount of usable real estate in this solar system is limited to our home planet. And as for planets around other stars, so far we’ve seen mostly close-in gas giants and worlds far stranger and less hospitable than those here at home.4
But why am I being so negative, when I said earlier that our next step is off the planet and into space? Because the challenges that await us are formidable. Compared to them, Columbus or Drake only had to deal with leaking planks, brackish drinking water, fearful crews, and hostile natives who were still, at a biological level if not culturally, indistinguishable from themselves. Columbus and Drake and all the others who opened our planet’s horizons simply needed courage and funding. To go into space, we’re going to need courage, funding, and a depth of scientific and technical understanding we don’t yet fully appreciate.
But the alternative is to remain here as part of the flora and fauna, to wait for the next big rock or advanced species to wipe us out. If we don’t go, humanity’s tenure on this planet is not indefinite. We might not even last another ten millennia.
1. Proposed by physicist Gerard K. O’Neill in 1976, these are huge cylinders—five miles in diameter, twenty miles long—which rotate to provide an Earth-like gravity. You live on the inner surface in shirt-sleeves and farm the dirt under sunlight coming in through huge longitudinal windows. The cylinders—actually designed in pairs, linked at the ends, so they counter-rotate for stability—could be placed at LaGrange points in the Earth-Moon system. The details need to be worked out, of course. The cost will not be cheap.
2. Early rumors that on Venus the rain was made of sulfuric acid have been largely dispelled, but that’s small comfort.
3. If we can one day learn to terraform the planets, how much of a problem will it be to adjust little things like the amount of trace gases in Earth’s atmosphere, adjust the wobble in our rotation, and smooth out any temperature flux not due to changes in the Sun itself? If you’re going to tackle living on the Moon or Mars, making a garden spot of the Earth on all of its continents and under its seas is a trivial exercise.
4. Of course, that may be largely due to our methods of detection, which look for changes in orbital and luminosity effects and so tend to favor large planets over small ones like Earth and Venus.
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