It's likely that no form of life ever existed on the red planet. Ancient or otherwise.
That leaves us with a real conundrum with respect to worlds like Mars.
Earth has experienced and undergone a countless barrage of both astronomic and geologic cataclysms. A large and significant number of these catastrophic events have occurred since life first took root in both the oceans and on the land. Some extinction-level events, or ELE's as they're known, were of such immense and devastating impact, that 90% or more of all life on Earth perished as a result. But as Jeff Goldblum says in the movie, Jurassic Park, ". . . life finds a way."
And on Earth, life has always found a way, once it got started. It's almost impossible to imagine, given the wide and wild disbursement of life on this planet, a situation terrible enough to destroy all the organisms that currently exist. No asteroid or comet, no eruption of a super volcano, earthquake, solar flare or gamma-ray burst could possibly kill every plant, animal, bacterium or virus that currently resides here.
But what about when life was less well established? The situation was even less welcoming back then, and what few life forms struggled to exact a modicum of existence, did so slowly but surely. Life always found its ways.
One thing is relatively certain: planet-wide catastrophes, when geologic in nature, happen slowly--over millions of years. On those rare occasions when a volcano, comet, or some other particular disaster transpires quickly, it's usually a more localized event. While the implications may be broad and deadly, not every nook and cranny, everywhere, is effected with the same lethal consequences.
Somewhere, some germ-like thing should survive and reproduce more of itself. And the whole process would start all over again. Just like it did on Earth, a thousand times over.
The great problem for life is the initial start-up. Still the greatest of mysteries, the gap between worlds likely teeming with life, and those barren and sterile remains a vexing enigma of existence. Once going, however, and if Earth is any example, the process is next-to-impossible to stop. Short of total destruction of the planet as a whole, countless microbes or even more sophisticated types, might well survive the worst disasters imaginable.
So what happened on Mars, that makes finding life, in any form, thus far akin to the proverbial needle in the haystack? Or in this case, a single diatom amid endless deserts of ice and sand.
Part of the answer lies in making an assumption, ignoring all other factors, that life indeed sprang forth at one time in the ancient martian past. It's pretty safe to say that presently, whatever that life was, has gone extinct. And done so everywhere, all over the planet. In the deepest cave, atop the highest mountain, within the residual ice of the largest ocean, something brought everything to an end. And did so fairly quickly by both geological and biological standards. Earth standards, that is.
If we therefore stand by the proposition that it was nearly impossible to destroy every bit of life after it had become established on Mars, the question is begged as to what calamity might have brought things to a screeching halt, all over the planet. Likewise another, more troubling quandary is posited which supports the far more likely notion that life was never spawned in the first place.
Both assertions are wildly speculative and require that certain beliefs are correct about the ancient, martian past. One such premise relies on the idea that while life on Mars may very well have gained an early foothold, enough geologic changes happened over a relatively short period of time, that whatever organisms existed, were abruptly cut short.
It is demonstrably true that on Earth, life began soon after a molten crust cooled and lots of water lay about as large, inland seas. Prior even to the arrival of oceans. To suggest that the same events took place on Mars is not only likely, but highly probable. We may never know the answer, at least in the foreseeable future. Not until humans ultimately explore the martian surface, both above and below.
For the time being, the multitude of roving probes, orbiting cameras and measuring devices, tend to indicate, and strongly so, that if life ever began on Mars, it ended just as quickly. Had it not, the evidence today, whether microscopic or tree size, should have already been overwhelming.
The reason such an assertion is probably more true than false, lies in an imaginary scenario whereby life began in much the same way on Mars, as it did on Earth. So far, so good. We then postulate what happened next, over a relatively short period of time. On Earth, the first bacteria, with their ability to mutate, adapt and evolve quickly, and spread by winds, sea and ocean currents, soon occupied a wide variety of planet-wide locations. It wasn't long before nearly every square mile of water, and eventually the land itself, was veritably saturated, inundated with living, squirming, mutating, ever evolving bits of organic flotsam and jetsam.
Meanwhile on Mars, possibly before they did on Earth, these same life processes were equally as active and prolific. As martian temperatures slowly dropped lower, as the atmosphere gradually thinned, as its oceans eventually dried up and magnetic field vanished, life should have, could have, found a way. Via any and all manners of mutation and adaptation, with Darwinian natural selection in full swing, life ought to have persevered. But it didn't. Something halted everything everywhere, with no second chances.
Either that, or things never got started to begin with. Given this as the more likely scenario, we would expect to find on Mars exactly what has been found. Which is to say nary an inkling of anything whatsoever. This does not bode well for what lies ahead as we explore the balance of the solar system. Lots of enthusiasm has been expressed over what amazing discoveries yet await us, that yet lie in wait amid the subterranean oceans of any number of mysterious moons orbiting much larger, less hospitable parent planets.
But another theory, however, that life came to Earth from elsewhere, maybe beyond the solar system itself, may hold the key answers to all our questions. If both the lands and seas of Earth were seeded by comets and asteroids, then the warm oceans beneath the frozen surfaces of Jupiter and Saturn's satellites were probably sheltered from the bountiful gifts of their distant visitors.
On Earth and Mars, the spores of life took root, were fruitful and multiplied. Venus and Mercury were much too hot and no green thumb, natural or otherwise, ever stood a chance. But things were just right on Earth.
And they almost were on Mars as well. But not quite. The martian oceans were a little too salty, maybe. The summers didn't last quite long enough. Winters a smidgeon too cold. For now, who knows the reasons?
One thing's for sure. For now. No one is answering the phone or taking our messages.
"Hello? Hello, can you hear us now? Hello?!"