In 2013 astronomers compiled and analyzed 4 years of data from NASA’s orbiting Kepler telescope to compute how many exoplanets lie in the “Goldilocks” zone of their solar systems, where surface temperatures could support the presence of liquid water. Their conclusion; approximately one in five sun-like stars harbors a roughly Earth-size planet in the zone. Extrapolating this on a galactic scale means that the Milky Way galaxy contains 11 billion (Harvard study) to 60 billion (University of Chicago) possibly habitable planets. The closest habitable planet could be as little as 12 light years away.
Also in 2013, other NASA-associated scientists analyzed marine fossils from worldwide sedimentary strata, measuring the oxygen isotope levels which indicate temperatures prevalent at the time of deposition. Their conclusion; if it weren’t for greenhouse gases, a cooling trend that began 5,000 years ago would likely be continuing, advancing Earth toward another ice age. Instead, they project, global warming will heat the planet between 2 and 12 degrees Fahrenheit further by 2100. Human-caused effects, in other words, are outweighing natural variations within a planetary system close to equilibrium.
The kind of warming they project would put Florida climate in Kansas, and Kansas climate in Saskatchewan. Alligators in Kansas? Would such a development indicate that we are actually interested in and capable of being effective stewards of this planet or any other? We know that this planet is precisely what we need; there is no guarantee that the closest habitable planet would be any more marginally habitable, at best, than the Sahara, or the Antarctic, or even Mars.
But all of that is moot. Using present technology, we will not be able to cross the 12+ light year gap to a dubious second home. Using ion-drive propulsion far improved over what we have used so far, a craft would take 70,000 to 80,000 years to cross the 4.3 light years distance to the red dwarf star Proxima Centauri. Gravitational ‘slingshotting’ could possibly reduce this time by 50 to 80%. Pulsed nuclear propulsion, if perfected, might reduce the trip to 100 – 200 years. In any instance, it seems inevitable that we would need to maintain an interstellar ark for generation upon human generation. But, if we can’t care take this exquisitely perfect planet with all of its richness of resources, how could we possibly maintain a tiny closed system? If we can’t prevent ideological war and resource conflicts when surrounded by a perfectly breathable atmosphere and effortless biological productivity, how could we possibly keep from each other’s throats in the confines of a metal tube in endless darkness?
Starwars is fiction. Stargate is fiction. Startrek is fiction. That we can screw up the delicate balance of our life-sustaining planet is increasingly being shown to be fact. That maintaining those life-sustaining systems in the face of our technological aspirations will be hard to do is also fact. That we absolutely have to find a way to become effective planetary stewards is the most important lesson that humans must learn, and we must learn it very soon. It is the prerequisite to any human future.