Could There Really Be Life on Mars?
The water situation
2 years ago, the requirement for all life was found on the red planet. Liquid water.
We always believed that water could exist on Mars, but for many years we were never able to find it. Well, we have now.
An entire lake full of that beautiful H20 was detected by Europe’s Mars Express Probe (which has been orbiting the planet for several years).
Fun fact: The Mars Express Probe was updated from Windows 98 only a month ago!
The lake is estimated to be 600 square kilometres in size, and 1.5 kilometres below the surface of Mars’ South Pole. It would be lovely to have a lake on the surface just like Earth, but of course, that is not possible.
Why? Mars has a negligible magnetic field.
This is a problem because a magnetic field acts like a blanket of protection. It blocks most of the harmful particles in the solar winds, and keeps an atmosphere inside nice and snug.
Consequently, Mars has virtually no atmosphere.
This led to Mars becoming the cold, barren desert we know today. With an average temperature of -60 degrees Celsius, it is not possible for water to exist in liquid form on the surface.
That said, it can exist as ice. We see this at the north and south poles, and even in some other sheltered spots across the planet.
And so we’ve always understood that our only hope of finding Martian liquid water is to look underground.
Young Mars was different
Despite our dream of surface lakes on Mars being unfulfilled, it was the case 4 billion years ago.
Mars has not always had a negligible magnetic field. In its early life after the planet formed, the field was reasonably strong. This prevented its atmosphere from being lost to space.
During this period, likely on the order of a few hundred million years, Mars may have looked somewhat similar to Earth. It would have been warm and wet, potentially covered with oceans.
Many scientists believe that during this period, Mars may have supported life. The conditions certainly could have allowed it.
And even more interestingly, some hypothesise that life did not originate on Earth. But rather, it began on Mars and was then transported to Earth (e.g. by an asteroid).
What about today?
Well if we assume it did exist in the past, surely there is no reason why it can’t still be there? The life harbouring conditions of Mars’ past are that of being “warm and wet”.
We have already found underground liquid water, so these locations are clearly warm enough for water not to freeze. Are these locations not “warm and wet”? Could life exist there?
We are forgetting one other factor which is essential to life: light.
It’s said that all life requires light. It’s the base of the food chain. Plants require light to produce energy and grow (photosynthesis). Then herbivores eat those plants. And omnivores and carnivores eat those herbivores.
Although light doesn’t jump to mind at first when considering biological requirements, without light there would be no ecosystem. No life.
The difference between the underground lakes of today and the surface lakes of billions of years ago, is light. For that reason, it seems impossible that life could exist on Mars today.
But there is still a chance. Chemotrophs.
Our last hope
Chemotrophs are organisms that obtain energy through a chemical process called chemosynthesis, rather than by photosynthesis. The energy is generated by the oxidation of reduced compounds, including inorganic molecules.
In other words, chemotrophs don’t need light.
These organisms are prokaryotic, rather than eukaryotic, and include both bacteria and fungi. On Earth they can be found in harsh, low-light environments such as deep sea thermal vents.
They are rare organisms, and it is unknown as to whether they originated entirely without light, or if light was required at some point in the evolution process.
Either way, they are able to survive without light today, even if light played a part in the past.
Therefore, if life exists on Mars, we can say it probably existed on the surface billions of years ago when the conditions allowed it. Then, as the atmosphere and magnetic field disbanded, it must have followed the water and moved underground, evolving to survive in a zero-light environment, becoming a species of chemotroph.
Chemotrophs are prokaryotes only, so any eukaryotic life on Mars would not have survived. Since prokaryotes evolve to become eukaryotes, this is the reason why life on Mars would not have evolved any further after it went underground, despite potentially existing for billions of years.
The chance of all this happening seems impossibly slim, but it’s still a chance. At least now we know where to look!
Anywhere else?
While it may be dissapointing that the chance of life on Mars is so slim, think about this: we are literally looking at our next door neighbour. Given there’s a chance that life may exist right next to us, then surely, on the grand-scale of the universe, life should be teeming!
My belief is that there is definitely life out there, but it’s not sentient. Or at least if it is, it’s so far away we can’t reach each other.
As we can see with Mars and Earth, it’s not uncommon to have life harbouring conditions, and I refuse to believe life hasn’t formed elsewhere.
However, as possibly seen on Mars, it's uncommon for such conditions to exist long enough for life to evolve past the prokaryotic stage, let alone becoming sentient. The fact we are here today is a result of a huge amount of luck over the life span of the Earth.
So lucky that there probably isn’t anything like us within a traversable distance, otherwise they would have come and found us by now! This comes onto the Fermi paradox, which I wrote about here: https://williamfahie.medium.com/do-aliens-exist-6e0d446cc385
Wow, you made it to the end of my article! Thanks for taking the time to read. If you have any of your own thoughts, please do respond — I’d love to hear your ideas. If you enjoyed, a follow would be hugely appreciated!
Sources
- Life on Mars: https://medium.com/predict/positive-results-showed-life-on-mars-7d46531af3f9
- Mars Express finds liquid water: https://scitechdaily.com/mars-express-spacecraft-has-discovered-liquid-water-ponds-buried-under-the-martian-surface/
- Young Mars was warm and wet: https://www.space.com/41686-did-mars-once-dance-with-venus.html
- Do all living things depend on sunlight?: https://www.quora.com/Do-all-living-things-depend-on-sunlight
- Chemotrophs on Mars: https://marsnext.jpl.nasa.gov/workshops/2018-10/PRESENTATIONS/m2020_lsw_day1_05_westall.pdf
- Info about chemotrophs:
- https://en.wikipedia.org/wiki/Chemotroph
- https://courses.lumenlearning.com/wm-biology2/chapter/how-prokaryotes-get-energy/
