If an observer were to dip their head inside the space industry, one would notice the rush to settle humanity either on the Moon, Mars or upon future space stations orbiting Earth. There seems to be a mass movement dedicated towards ensuring that our species establishes a “beta home” elsewhere, just in case we are wiped out from either an asteroid or a biological and/or nuclear war.
But if we were even able to settle on other terrestrial bodies tomorrow, would our species be able to survive without Earth?
Unlike the other worlds that orbit our star, Earth lies in what many scientists regard as the habitable zone. Within this region of space, a planet hosting a friendly atmosphere can have liquid waters gracing its surface, an important feature enabling complex ecosystems to survive (let alone thrive).
Other worlds such as Mars lie outside of this zone, and despite showing signs of harboring liquid water within its soils, it lacks the sufficient temperature to maintain water in this state upon its surface. Although some argue that aggressive terraforming could alter Mars into a second Earth, it would take at least a thousand years (if not longer) to transform this barren world, not to mention trillions of dollars.
Unlike most other rocky bodies in the solar system, Earth also boasts a magnetosphere, a key ingredient required for living organisms as cosmic radiation is not known to be healthy. Although both the Moon and Mars each maintain an active magnetosphere, neither are strong enough to cover their entire worlds, respectively.
Even though Mercury and Jupiter’s moon Ganymede boast a global magnetosphere, both are either too close or too far away from the sun to host vibrant environments for plants and animals, at least in the near future.
Unlike Earth, most (if not all) of the worlds and moons that orbit the Sun do not harbor soils that are generally friendly towards plant life. Although Mars is often regarded by many as humanities second home, its soil may be too toxic for growing plants upon it directly.
Despite the fact that our lunar neighbor shows some promise (however small), it lacks large bodies of water necessary to support life on that airless body.
Even if humanity were able to transport millions of people upon the Moon and Mars, and yet lose Earth, our species would probably face the cold reality of extinction. Establishing colonies upon other worlds is no guarantee towards our survival abroad, as colonies would still be dependent upon Earth for tons of fertile soil for growing grain (as well as animals for meat) in the near and distant future.
Whether by cosmic chance or divine will, Earth is the oasis of the solar system, the only world capable of supporting life without the need of biospheres (something we still have not perfected). Earth is the “only Eden” that humanity has, whether we like it or not. Outer space is an opportunity for our species, one that can drastically improve life upon our home world whether it be through energy, communication, agriculture or medicine.
But space (with all of its resources) could never replace our world, and if our species can not take care of our Earthen cradle, then there is no guarantee that will be fit enough to survive on a second world.