Mars is a pretty horrible place for any creature used to life on Earth. The average surface temperature is -63°C (-81°F) and doesn’t reach above freezing anywhere except right on the equator, during the summer.
The atmospheric pressure is equivalent to Earth’s at an altitude of 35km (almost 115,000ft) – well above the cruising altitude of commercial aircraft. And this thin atmosphere is nearly all carbon dioxide, with just the merest trace of oxygen.
Then there are the radiation levels, which are 400 times higher than on Earth, plus the lack of liquid water anywhere, except for occasional, very salty, trickles.
Despite this, there are a few Earth organisms that have shown some capacity to withstand these conditions.
The European Space Agency ran a series of experiments from 2008–2016 in which a variety of organisms and seeds were given simulated Martian conditions while aboard the International Space Station.
Tardigrades, fungi and some bacteria survived for over a year, but only when in a dormant state, such as a spore or cyst.
Some lichens and algae were able to go further, demonstrating some actual metabolic activity if they were partially shielded from the radiation. On Mars, this might be possible if they were buried in the soil or sheltering in cracks in the rocks.
In 2024, Chinese researchers showed that a variety of desert moss (Syntrichia caninervis) was able to withstand Martian conditions. But again, ‘withstanding’ is a long way from actually thriving.
The moss recovered after a week in simulated Mars conditions and was able to grow normally again, but the researchers couldn’t find any evidence that the moss was metabolically active, for example by producing oxygen, while it was in the Mars environment.
But wait, it gets worse.
Martian soil contains perchlorates, which are rather nasty oxidising agents that are toxic to cells and cause DNA damage. And when they’re exposed to the ultraviolet light that shines on Mars, they become even more reactive.
The Chinese experiment didn’t include perchlorates in their simulated Mars environment; if they had, it would have probably killed the moss outright.
There are some fungi that can survive perchlorates and a few species of bacteria that can even use it as an energy source and break it down to harmless byproducts. But these species also require water and warmer temperatures to live and grow.
Here on Earth, when we preserve something, we use a variety of methods to kill bacteria and fungi, or prevent their growth.
We put food in the freezer, dehydrate it, sterilise it with UV light, pickle it in brine and other salts, or seal it in a container under a vacuum or with an inert gas to remove the oxygen. Mars, is all these things at once!
If we were trying to sterilise the planet, we would struggle to do a better job than Mars has already.
This article is an answer to the question (asked by Robin Mason, Manchester) ‘Is there anything on Earth that could withstand conditions on Mars?’
To submit your questions, email us at questions@sciencefocus.com, or message our Facebook, X, or Instagram pages (don’t forget to include your name and location).
Check out our ultimate fun facts page for more mind-blowing science
Read more: