Here’s a look at each of those resources, in the order of ease Mc Kay predicted they would be accessed: Mars’ atmosphere is its most easily accessible resource, providing feedstock for manufacturing methane propellant.
The chemistry involved in separating it is simple, low power, and has been employed on Earth for more than a century.
When pressurizing large surface habitats, an inert buffer gas minimizes the amount of oxygen required and reduces the risk of fire.
The second and third most prevalent gases in Mars’ atmosphere (nitrogen and argon) fill this role very effectively, and can be easily separated with technologies borrowed from the terrestrial chemical industry.
But that doesn’t always answer the question of whether humans can a given environment.
After all, Earth’s South Pole doesn’t have liquid water on the surface. Yet resourceful humans have been inhabiting both locations for decades. Mars is on the outer boundary of our solar system’s habitable zone, and we know what looks like briny, liquid water can exist on the surface for short periods of time. From a practical standpoint, the answer depends on what technologies we bring there to create our own artificial habitable zones on the surface.Long-term habitation on Mars will require us to master the conversion of raw Martian materials into resources we can use to survive.Fortunately, Mars has a wealth of these materials, making it arguably the most human-habitable place in the solar system, other than the Earth itself.that some cyanobacteria, when put in a chamber simulating Mars surface conditions (same air, temperature, pressure, UV, etc.) and partially in the shade, are able to show measurable activity and carry out photosynthesis, absorbing humidity from the atmosphere (relative humidity reaches 100% at night on Mars).Lichens, which are multi-cellular lifeforms, did the trick as well!And while cosmic rays can penetrate meters of regolith, their level on Mars is similar to those in the ISS.Therefore, radioresistant terran extremophiles (there are many) could definitely survive them for thousand of years in complete dormancy — just as they would survive the occasional solar storms until they reach the safety of a possible Mars surface habitat where they can wake up.We have so far identified—let alone DNA-sequenced—a very limited share of the Earth’s microbial world.Some microbiologists say there are probably thousands of billions of microbe species on Earth, 99.999% of which have not been identified!So in case of a mix up with Earth and any potential Mars life, how are we supposed to tell one from another?Why again take such a huge risk to confuse the study?