a reply to: stormcell
The circumstances in which subterranean life on Earth finds itself, are very different from the circumstances that lifeforms inside the planet Mars
Here on Earth, both the life forms under the ground, and those living on the surface, benefit from the geothermal processes occurring inside our
planet. Although volcanism, quakes, and the like can cause harm, they also provide heat, and on the ocean floor, life from the bacterial, right up to
complex lifeforms, have been observed feeding on the mineral deposits spewed out of what are called black smokers, columns of deposited material from
places where the molten sea of rock that our continents float on, pushes gases and material outward in a steady flow, into the ocean. These deposits
are fed on by the hardy creatures who can survive that otherwise hostile environment. There are even bacteria which, although only recently
discovered, can allegedly process radiological material, into a source of sustenance.
No matter where you find volcanic activity, there is always some mineral given off that might sustain one or another invisible critter, and perhaps
some complex, multicellular life as well.
However, from what we understand of Mars so far, it has little to no active core. That is to say, that it has no geothermal process at work, which
A) There is no material being deposited from within the interior of the planet, to the crust or any layer thereof, and therefore any lifeform which is
analogous to those I describe above, will find slim pickings when looking for a life sustaining snack.
B) There is no heat being exchanged between the interior, and the exterior of the planet, which in turn means that no heat is being provided to life
forms in the crust, or any layer thereof, and that presents a whole other range of issues. Life at the very small scale finds it hard to provide its
own heat sources, lacking the space within its construction to store vast amounts of burnable energy for later. It often relies therefore, on a higher
ambient temperature environment, in order to flourish and grow, or even simply get on with the business of being a living thing. Heat is basically an
expression of kinetic energy at the molecular level, and without it, life is difficult to maintain.
C) All of this means that if there IS life on Mars as we speak, it must be very simple, and virtually unrecognisable as being life at all from our
limited perspective, not to mention hard to locate. The reason I say this, is because any lifeform that can survive with virtually no volatile
chemical input, heat, light, or other consumable source of energy, must have a VERY slow metabolic rate, and therefore must output very little waste
gas, or other trace which might give it away.
It also means that life would have to be in isolated pockets, around the solid mineral versions of the sorts of compounds and elements which make for
good nosh for lifeforms. Although we have not the knowledge base yet to know what is POSSIBLE in terms of life, and how it CAN form, we know which
compounds are easiest to convert into energy using bio processes on Earth, and so we have to extrapolate from those, which are more likely to
represent a food source to a lifeform on or inside Mars. Because there is no vegetation on Mars, the sort of stuff you find in fertiliser (which is a
GREAT food source for bacteria and other tiny critters), is not going to be knocking about in massive quantities, so the raw mineral versions of the
contents will have to be located, and investigated to see if they are home to swarming islands of bacterial life.
It will be interesting to find out though!