![]() One species was discovered all snug and cozy in the intestines of a termite. Many species live in soggy soils, such as marshes and swamps. If life ever emerged on Mars, it might never have evolved beyond this primitive stage.ĭesulfovibrio makes its home in a variety of habitats. Early life had to get its energy from chemical interactions between rocks and dirt, water, and gases in the atmosphere. In fact, photosynthesis came relatively late in the game of life on Earth. Chemoautotrophs also make their own food, but they don’t use photosynthesis to do it. They’re photoautotrophs: they make their own food by capturing energy directly from sunlight.īut Desulfovibrio is not a photoautotroph it’s a chemoautotroph. Not only plants, but many microbes as well, are capable of carrying out photosynthesis. After all, we see green plants nearly everywhere we look and virtually the entire animal kingdom is dependent on photosynthetic organisms as a source of food. We tend to think of photosynthesis as the engine of life on Earth. Microbiologists have identified more than 40 distinct species of this bacterium. What kind of microbe, then, would have been well adapted to the conditions that existed when Eagle Crater was soggy? Benton Clark III, a Mars Exploration Rover ( MER) science team member, says his “general favorite” candidates are the sulfate-reducing bacteria of the genus Desulfovibrio. In fact, there are few habitats on Earth where one or another species of bacterium can’t survive. ![]() They are amazingly diverse, various species occupying extreme niches of temperature from sub-freezing to above-boiling floating about in sulfuric acid getting along fine with or without oxygen. It took life on Earth billions of years to evolve beyond single-celled organisms. But that’s not much of a limitation, really. No dinosaurs no redwoods no mosquitoes – not even sponges, or tiny worms. Even if life did gain a foothold on Mars, it’s unlikely that it ever evolved beyond the martian equivalent of terrestrial single-celled bacteria. What type of organism might have been happy living there? ![]() So suppose that Eagle Crater – or rather, whatever land formation existed in its location when water was still around – was once alive. But liquid water was there, at the martian surface, and that means that living organisms might have been there, too. And billions of years might have passed since it dried up. ![]() The discoveries made by NASA’s Opportunity rover at Eagle Crater earlier this year (and being extended now at Endurance Crater) leave no doubt that the area was once ‘drenched’ in water. Life, as we know it, could have taken hold there. What the evidence does indicate, though, is that Mars was once a habitable world. But so far no evidence has been found that convinces even a sizable minority of the scientific community that the red planet was ever home to life. Was Mars once a living world? Does life continue, even today, in a holding pattern, waiting until the next global warming event comes along? Many people would like to believe so. ![]()
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