Physicist Stephen Hawking argues that Mankind must build starships and spread itself throughout the galaxy in order to survive, since Earth’s years are clearly finite. Hawking has made this case many times, being convinced that even a smallish catastrophe (like a massive meteor strike) could render Earth uninhabitable for humans, and it could do so at any time.
I wouldn’t presume to contradict Hawking; in fact, I agree with his assessment of the fragility of our ecosystem and its prospects for long-term viability. But when it comes to his opinion that we should leave Earth for our own survivability, I have another option. I don’t think we need to leave Earth; I believe we can stay longer, even through a catastrophe, if we apply proper husbandry to the Earth. And we can do that if we move the bulk of our population into orbital satellites.
Hawking suggests that we essentially use what we can here on Earth, then pack up and abandon it… much like our nomadic ancestors would use up a region, hunting out its game and farming its land into sand, then move on. He postulates either generation ships, or starships that can exceed the speed of light, to take us to distant planets in other star systems. He assumes that we will be able to find such a planet or planets, Earth-similar bodies in the “Goldilocks” zone of habitability, ready for life but apparently without established life of its own, just waiting for us to arrive and plant our flags (and then, presumably, our figs).
This assumes a lot, to my mind: For one thing, since we don’t know how to build an FTL drive, it assumes we can build ships capable of sustaining us for years, decades or even centuries in open space, far from any source of supplies replenishment or aid, which would be a damned impressive engineering feat (if even possible); but perhaps more importantly, it assumes that we have the right to take over planets that suit us, even if they have their own established life—for any planet capable of sustaining life almost certainly will have life of its own when we arrive—much as we have occupied regions already occupied by other humans and creatures and pushed them out for our own purposes. This intergalactic “manifest destiny” sounds too much like what we’ve done on our own planet, and it’s only brought environmental and social damage to our own history. Is that really something we want to take to the stars?
I say that with wiser husbandry, we can last much longer on our chosen range. First in our agenda should be making Earth more sustainable for us, right now. In much the same way that our agricultural ancestors learned to properly tend farmland, rotating crops and replenishing soils with needed nutrients, we can learn how to slow the process of turning our own planet into a dustbowl. We can better use resources, better avoid damage to the environment, and better make sure the environment is capable of being restored (and restoring itself) from our manipulations.
We could much better do that by moving the bulk of our population off of Earth, and into orbiting city-satellites like those touted by Gerard O’Neill’s book The High Frontier. We are on the verge of learning enough about using available resources, recycling used resources and being more efficient in our energy and waste usage to be able to enclose our ecosystems almost completely, removing ourselves from the fragile environment around us. Habitats orbiting in space can take full advantage of the wealth of solar energy pouring out around us to power themselves, and will have the opportunity to use centripetal force selectively, rotating in areas to provide simulated gravity where humans and other organisms need it, and maintaining gravity-free areas that can aid manufacturing, heavy machinery operation and other activities. Freed of gravitic and geological constraints, we can design and build our satellites in any configuration we see fit, making sure they are organic and flexible enough to be modified as the population changes over time.
We will still need resources from Earth, of course; no orbital system should be assumed to be completely closed (at least, not for the foreseeable future). But our new living arrangement will demand that we apply much more sensible and efficient practices in gathering what we need and using it wisely. Small populations will remain on the ground, mostly tending to what equipment we use to collect raw resources and prepare them for shipment into space. We will truly become Earth’s shepherds, tending our charge without doing damage to it, and making sure it will serve us through the future.
And what about the “smallish catastrophe?” If something like a meteor strike or a major volcanic eruption (like the Yellowstone Caldera is expected to give us… well, any time now) occurs, the Earth will suffer from major physical and ecological damage that may take decades, centuries, or even longer to properly recover from. But if we are mostly in orbit, we will be in a much better position to weather out such a catastrophe, orbiting above the upheaval and returning to Earth only when it is safe or absolutely necessary. If we are living efficiently in space, we will hopefully be able to monitor the disaster and determine when and where it will be safe to return for supplies and resources. Small ground-based populations would be much more capable of quick evacuation (to the satellites, presumably) in an emergency. A significant geologic disaster may even upturn and reveal long-buried resources, making it easier to detect and collect them. We may need to wear protective gear or take other survival steps where, in the past, we did not, but we will ultimately still have access to the resources of the planet that birthed us.
This would allow humankind to live much longer off of the bounty of the Earth, giving us more time to prepare for the next stage of human exploration… for, assuming we live long enough, we will eventually see the Sun nova, then die, and we will have to leave the Solar System whether we like it or not. Maybe before then, we will have moved some of our orbiting habitats to the outer planets, perhaps living off the resources of Jupiter’s or Saturn’s moons, or the asteroids, and extend our stay in the Solar System as long as possible before our forced eviction.
And most likely, we will have to stay in our self-contained homes, because—even if we should figure out how to get them to other stars—it is still highly unlikely that we’ll find a planet conveniently similar to our biological needs to allow us to simply land and move in (and I’m not assuming terraforming an entire planet will ever really be more than a pie-in-the-sky notion). More likely is that we’ll find planets with resources we can use to help sustain us, just as we will have used the Earth’s resources while staying in orbit; we will settle in orbit around those new worlds and begin the process of shepherding them to help sustain us.
This was the logic behind my worldbuilding of Verdant Skies and Verdant Pioneers; the major difference being, in the Verdant books I postulated a worldwide budgetary crisis that ended the City-Satellite project after only four of them had been built, and that the majority of Earth’s population unfortunately remains down on Earth’s surface when the story takes place. But the Verdant series also postulates that a way to travel to the stars was found when a crisis demanded it, returning us to the goal of mankind’s being able to spread out among the stars and preserve its own future survivability.
Which way will Mankind go? Off in starships to other worlds, as Hawking suggests? Remaining in the Solar System in space habitats? Or moving those habitats to other stars? Only time will tell.