Elon Musk, the billionaire founder and CEO of the private spaceflight company SpaceX, wants to help establish a Mars colony of up to 80,000 people by ferrying explorers to the Red Planet for perhaps $500,000 a trip.
(...) we've put all our eggs in one basket. If we were on many worlds and were to mess up down here, there's a way for the human species to continue. I don't for a moment propose that the Earth is a disposable planet, and we have to put enormous efforts into making sure we don't muss up down here. But there is a chance.
Which catastrophic risks does a mars colony mitigate ? Using a list from a recent post by Stuart Armstrong (table by Anders Sandberg) ...
Earth impactors : yes
War : probably. Unlikely that Mars colonies would be valuable or strategically important enough to extended a war to Mars, but possible that the same conditions that led to war on Earth could lead to local war on Mars, or that war on Earth could be exploited by factions on Mars
Famine : yes. Keeping a Mars colony fed might be a major challenge especially at first, but independent of the same challenge on Earth. If famine on Earth is caused by a plant pathogen, it could spread to Mars, but there is the nice long quarantine.
Pandemics : probably. Until there is much more advanced propulsion technology that cuts trip time to days, the trip serves as a natural quarantine period. Also, really nasty features like the ability to persist in the environment, or replicate in non-human hosts, or spread via aerosols, don't present any additional threat on Mars.
Super volcanos : yes. Also, unlike e.g. impactors, there probably isn't an equivalent Martian hazard.
Supernova, GRB : probably ? Unlike impactors, a supernova or GRB would affect both Earth and Mars. However, if the major impact on Earth is deaths by radiation of exposed people and destruction of agriculture by destruction of the ozone layer, then Mars should be much more resilient, since settlements have to be more radiation hardened anyway, and the agriculture would be under glass or under ground.
Climate change : yes
Global computer failure : probably not ? If Mars colony infrastructure is very robustly designed it might survive without computers. I expect that it would not be possible to software quarantine Mars.
Bioweapons : probably. For Mars to be included in a deliberate pandemic attack, you would need to get the agent into each separate Martian settlement, probably simultaneously. Unlike Earth, separate Martian cities could probably enforce effective travel restrictions and quarantines.
Nano weapons : no. Unlike bio weapons, presumably all you would have to do would be get some spores to somewhere on Mars.
Physics threats : depends on scale of disaster. Merely planetary scale ones (e.g. black hole eats Earth quietly), yes. Larger scale, no.
Super intelligence : no
A few of points that occurred while going though the list.
The above is assuming that the Mars colonies are self-sufficient, otherwise a catastrophe on Earth is a catastrophe for Mars.
Eexistential risks are described a causing actual human extinction, or massive mortality and long term curtailment of human progress (e.g. putting human population and society back to the Stone Age). Mars colonies mitigate against the first, and could mitigate against the second if Mars is developed to the point where it is wealthy and has an independent space program - to the point where Mars could offer meaningful aid to Earth.
If we can build a self sufficient small scale economy which is independent from earth's ecosystem services and industry base - i.e. an independent martian colony - most listed existential risks a martian colony might mitigate cease to be existential. This is since the mechanism of these existential risks is reduction of ecosystem services provided by earth's biosphere triggering a breakdown of our interconnected world economy with subsequent starvation of most people or even a breakdown of our interconnected world economy without significantly reduced ecos... (read more)