Climate change is rapidly making the Earth's atmosphere unsuitable to human life, as industrial and international pivots to sustainable energy goals aim to secure the common future of humanity.
However, when multiple threats to the existence of human life happen at the same time — like the climate and COVID-19 crises — the question of long-term survival arises. We'll almost certainly beat the COVID-19 crisis, and the species stands a good chance at overcoming climate change in the long run.
But someday — billions of years from now — the Sun will ultimately obliterate the Earth. A recent study published in the journal Nature Astronomy offered a glimpse of Earth-like crusts floating about their host star system. While none of us will be around to see Earth reach a similarly final stage, it raises the question of how humanity will survive Earth. If it can.
Elon Musk's two-planet species plan for Mars
A year ago, Elon Musk tweeted new details about his plans to settle Mars with his aerospace company, SpaceX — suggesting a viable human presence could take seed on the Red Planet by the mid-21st century.
If we take Musk at his word, the entirety of SpaceX's launches and deals — from commercial rideshares and Starlink satellites to low-Earth orbit, the contract from NASA to launch parts for the forthcoming Lunar Gateway, to the exploding prototype Starships — are united in a single mission to establish a permanent human presence on Mars.
With human populations on both Earth and Mars, the species stands a better chance of surviving extinction-level events, since — barring a rogue black hole singularity, unusually monstrous super-solar flare, or nearby supernova — such events have yet to be seen on both planets at the same time.
SpaceX aims to put humans on Mars by 2026
The challenge, of course, is developing a new comprehensive suite of engineering and technology to support humans in environments inherently deadly to human bodies. One day we might terraform the Red Planet — thickening and altering its atmosphere to support human life — but this could take centuries, or longer.
Jupiter's moon Titan could host an insulated colony
Since the European Space Agency's (ESA's) Hydrogen probe touched down on the surface of Jupiter's moon, Titan, researchers have considered the planet for possible colonization.
Unlike the moon and Mars, Titan has the densest atmosphere of any moon in the solar system — which would serve as protection from solar radiation. The Jovian moon may also have large bodies of liquid hydrocarbons in methane and ethane seas — which could serve as fuel.
Titan also likely has water, in addition to abundant natural resources — with which future astronauts could construct and maintain a base.
Life beyond the solar system
While Venus and Europa could also support small habitats — in the clouds and under the ice sheets of each body, respectively — the most effective way for humans to survive local extinction events is to spread beyond our solar system.
The nearest star system Alpha Centauri is roughly 4.4 light-years away — which means it would take nearly 4.5 years to arrive at the system if we moved at the speed of light (which is not theoretically possible). This is especially vexing since new research pointed to a possibly life-sustaining world orbiting in the habitable zone of Alpha Centauri A.
Generation ships are an enormous commitment
Sadly, conventional methods of chemical rocket propellant would take 19,000 to 81,000 years to reach Alpha Centauri. Additionally, a 2019 study suggested a generational ship — where humans can live and reproduce through the eons-long journey — would need to have artificial land to grow food, and be large enough to generate artificial gravity via spinning. This could mean a minimum radius of 735 ft (224 m), and a minimum length of 1,050 ft (320 m).
Barring such a hefty and long-term commitment, we could also simply "seed" planets throughout the galaxy with the building blocks of life — effectively conceding our species' survival to our home solar system while allowing other forms of life to evolve in radically alien environments.
Genesis project could ensure life evolves in other systems
Called the Genesis project, the interplanetary seeding endeavor would distribute microbial life on "transiently habitable exoplanets — i.e. planets capable of supporting life, but not likely to give rise to it on their own," said Claudius Gros of Goethe University's Institute for Theoretical Physics, according to a Phys.org report.
While we still have options to help humans survive Earth by settling other planets in our solar system, a relatively low-cost back-up plan could "jump-start" evolution on planets not likely to develop life independently and make sure the "light of consciousness," as Musk has called it, has a chance to evolve elsewhere. Just in case we don't survive Earth.