Rover Curiosity’s bore hole in Mars rock, note color change from reddish to gray
Scientific knowledge requires a process of confirmation, for example, scientists have believed for decades that Mars had water and may still have it either in ice form or in the underground. This belief started with observations drawn from Mars photographs from the earlier orbital missions in the 1960’s. Several decades later, the amount of confirmatory evidence is overwhelming. There’s no doubt Mars had water, probably lots of it and an entirely different climate. There’s still water on Mars, we know of the ice form; there remains a possibility of underground water.
Based on our Earth experience, where there’s water (liquid form), there’s life. Consequently, scientists have long speculated that at one time, or possibly even now, life existed on Mars. The evidence for that is not yet conclusive, one way or another; but pieces of the story continue to accumulate. The latest, and in many ways the most promising (short of actually finding something alive or remnants of something that was alive) are reports from a sample drilling made by Curiosity, the latest U.S. Mars rover.
Working in what is believed to be an ancient streambed in the Gale Crater; Curiosity drilled out a sample from sedimentary (water deposited) rock and then analyzed the sample in its on-board laboratory. One thing, visible immediately (see picture above), was a previously unseen transition from red rock/soil, which indicates an extreme level of oxidation (very life unfriendly), to a gray material only partially oxidized (life friendly). From the results of sample chemical analysis, scientists identified sulfur, nitrogen, hydrogen, oxygen, phosphorus and carbon – in quantities and combinations that are the key chemical ingredients for life (at least as we know it).
This is not evidence of life, past or present – only that life could have used these ingredients to develop and survive. They represent a rather typical and benign environment, similar to those found on Earth (minus available liquid water). This new information is a bit like the discoveries of amino acids and similar compounds in the rocks of meteorites. They are ‘indicative’ of life – found wherever life exists – but not evidence of life.
The current Mars in a very inhospitable environment – mostly it’s too cold, too dry and too bombarded with UV light to support any kind of life we know. The evidence suggests, ever more strongly, that this was not always the case. The Mars environment was quite different – however, that was probably a billion or more years ago. Conditions have radically changed, and if there once was life, where did it go? We have, as yet, no evidence about that – only supposition that if evidence of life still exists (alive or fossilized), it’s probably underground.
Another way to look at the new evidence is to speculate that since enough is known about the possible favorable conditions for life (water and appropriate chemistry) – if no life is found the huge question will be why? Or to flip the expression, if we find life on Mars (living or fossil), it won’t be that big of a surprise.
Now all we have to do is wait for confirmation…
[SciTechStory: Life on Mars: If it exists is below the surface]
[SciTechStory: Mars water: What’s all the fuss?]
