What do Firefly, Interstellar, and this painfully uninventive story have in common? That's right they're Sci-fi tales where humanity leaves the Earth because it's "used up" and travel to a new planet that is or can be made into our new home. While I don't hate every work that includes this I do cringe each time it comes up. There are a few assumptions encoded in this plot:

  1. Space propulsion will advance to the point where we can both escape the Earth's gravity well and accelerate to significant speeds.
  2. We can accomplish point one while experiencing an extinction event that we are not able to prevent.
  3. It's easier to travel to another planet and to terraform it than it is to fix an existing ecosystem which you have researched thoroughly.

I don't have a problem with point one, given enough time, but I take issue with point two and point three is right out. Right now it costs hundreds if not thousands of dollars per pound to get into geosynchronous orbit and the cost has not dropped significantly since the sixties. Even assuming the cost to get into orbit drops by a factor of ten or a hundred we are packing light. The propellant to mass ratio limits the maximum attainable speed for a given mass and said extra fuel increases the weight just getting out of the atmosphere.

But pretend for a minute that all of the problems are over come and we manage to get a cheap nuclear fusion drive. Those are, for what ever it's worth, the most powerful drive design we can easily conceive of. Now pretend that the Earth is doomed because we burned too many fossil fuels and the polar ice caps have melted, polar bears are extinct, etc. What is the most comfortable environment in the solar system? Is it:

A. The airless, tidally locked rock with the low gravity.
B. The smallish freezing planet with a thin CO2 atmosphere and ice at the poles.
C. The boiling hot, planet with the extremely thick atmosphere and months long days.
D. The only planet known to house life with abundant water, oxygen/nitrogen atmosphere and a solid industrial base

This is not a trick question. The answer is D: Earth. It remains Earth even if three quarters of the planet is underwater. It remains Earth if the whole planet gets irradiated. It remains Earth if the surface temperature goes up sixty degrees Celsius. We are going to have to work really hard to make Earth the second most livable planet in our solar system. If you want to get out of the solar system in the hopes of finding another planet that meets the fairly stringent requirements for us to stand naked under its sky and survive the experience then God help you. A hundred times faster than our current top speed of 157,078 mph is about 2.5% the speed of light which will get you to Alpha Centauri in one hundred and seventy five years. Hope you figured out cryogenics really, really well.

Logistical and technical issues aside what I hate about this trope is for that all that it portrays a dire warning about resource depletion it's an easy out. "Oh, we wrecked our home world? Well, we can just find a new one." Layer all of the tragedy and heroic sacrifices you want on top of it, people still see us moving out and living happily ever after. Not going to happen.

This planet is what we are going to have for a long time. I don't believe we can use it up because iron ore, carbon atoms, and matter in general don't stop existing just because you mined it out of the ground or threw it in a land fill. I do think we can wear it out. I don't want to see that happen and I don't want however many people actually think about this after they get away from the screen to think that their descendants are going to have the choice to get up and leave.


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