Is there life on Mars? We have no idea. We also don’t know whether or not life ever existed on the surface of this once more oxygen-rich, waterlogged world.
The new discovery of a massive lake of subterranean water on the Red Planet, however, has many wondering if this may be where we finally uncover whether or not we share the universe with microbial beasties. So could this lake – one that’s very likely not alone on the planet – be riddled with microbial life?
The short answer, of course, is that we don’t know. We can, however, do a bit of informed speculation to ponder on the possibilities.
It could be unfathomably uninhabitable down there for geological or environmental reasons we haven’t considered or encountered before. At the same time, it could be much like the water we find trapped in similar environments on Earth – and, as the mantra normally goes, where there’s water, there’s life, even if that water is salty, radioactive, icy, or near-boiling.
We obviously haven’t discovered life anywhere other than on Earth, which means we only have one highly limited working model for how life operates, evolves, and adapts. Adapt it has, though: As the science of microbiology has become more advanced, and its participants more daring, we’ve found life belonging to the Bacteria and bizarre Archaea kingdoms – and the more ambiguously defined viruses – everywhere.
We’ve found microscopic critters clinging to the sides of high-temperature deep-sea vents and buried within Earth’s crust, devoid of sunlight. We’ve found them in super-deep mine shafts, getting energy from sulfur that falls off rock being bombarded with radiation.
We find algae drifting on the wind currents high up in the atmosphere, sometimes blown up there by volcanic eruptions. We have found life trapped in suspended animation in giant gypsum crystals deep underground in cave systems. Viruses, by the way, are found in abundance, especially within Earth’s oceans.
Most pertinently, we have also found that subglacial lakes – kept liquid thanks to the high salinity content or pressure down there – in the most otherwise inhospitable places on Earth are packed full of microbial life. Even larger forms of life, like fish and crustaceans, can live off little more than methane in flooded cave networks on Earth.
Short of surviving in anything too hot, like lava, whose extreme temperatures destroy all genetic material, life is everywhere. There are as many as a trillion species in the world, and many are extremophiles: those that don’t just survive, but thrive, in environments we would deem to be too hostile to life we normally encounter.
No wonder speculation is rife that we could find life on other worlds, from the chilly waters of Mars to the warmer depths of Europa and Enceladus, and even to the hazy skies of Venus. Life is incredibly resilient, and it (almost) always finds a way.
If it’s managed to crop up within Mars, and it’s managed to leap over the evolutionary hurdles life on Earth had to, then of course we could find biology there. Data suggest it's pretty damn cold and salty, which makes living in it a bit trickier, but it's still liquid water shielded from harmful radiation.
Again, we don’t know. There's no evidence anything's down there at present. If we're being skeptical, we should assume there's nothing.
But, as Dr Ben Libberton, a microbiologist at the MAX IV Laboratory in Lund, Sweden, who was not involved in the paper, told IFLScience: “Water is a prerequisite for life as we know it, and now we’re not just seeing evidence that water could have been there – it’s actually there!”
He adds that water is vital for supporting life, but “perhaps more crucially” we now “have a good idea of what to look for, and where to look.”
We find extremophiles on Earth living in far harsher conditions than those within this new lake. Could something be shifting around in the ancient watery shadows within our planetary neighbor?