Humanity has long been fascinated by the possibility that there is life on Mars. While the search has been long and somewhat fruitless, scientists have still not lost hope that Martian life exists. Luckily, if life forms can survive on Mars, it's not the kind that can invade Earth.
Living on Mars can be harsh. The terrain is barren, extremely cold, dusty, there's little water, and the planet has also lost chunks of its atmosphere. With what we know about the conditions that can support life, Mars doesn't seem to be very hospitable.
However, there may be a particular life form that can survive not on the surface, but deep inside the planet.
Scientists detected traces of methane gas in Mars's atmosphere. On Earth, methane mostly comes from organic sources. Of course, volcanoes also produce methane, but much of the methane on Earth comes from living things. Two studies postulate that life could possibly exist on Mars in the form of simple organisms called methanogens.
Rebecca Mickol is the lead author of a study titled “Low Pressure Tolerance by Methanogens in an Aqueous Environment: Implications for Subsurface Life on Mars”. According to Mickol, methanogens are strong candidates for Martian life. “They are anaerobic, and non-photosynthetic, meaning that they could exist in the subsurface,” Mickol says of the organisms. Methanogens also produce methane as a byproduct, and methane has been found on Mars.
To test this theory, Mickol and her team ran an experiment on four species of methanogens. They put these methanogens under low atmospheric pressures that would exist under the surface of Mars. All four species survived these conditions between three to 21 days.
In another similar study, researchers took a closer look at the Martian subsurface. Pradeep Kumar, lead author of the study, and his team added the necessary presence of water to the equation. According to geothermal models, there would be liquid water about 30 kilometers under the Martian surface. However, whatever water there is down there would be subjected to certain pH levels, extreme pressure, and high temperatures.
Kumar and his team therefore replicated the probable subsurface conditions of Mars in a hydrostatic chamber. Their experiment showed that the methanogen species M. wolfeii survived the conditions it was in. “Our study raises an exciting possibility of methanogenic archaea to be a viable organism that can survive and possibly thrive in the subsurface conditions of Mars,” said Kumar.
Methanogens are simple microorganisms that belong to the group archaea. Archaea are single-celled organisms whose cells don't have nuclei or membrane-bound organelles. These organisms are ancient, and are prevalent throughout Earth. They survived the harsh conditions during Earth's early life, and they are still able to survive in the harshest areas of our planet.
The findings of the two studies are thus exciting. If methanogens can survive harsh conditions on Earth, then it might be able to survive on Mars. Though there is still a need for actual proof of life on Mars, we at least know now where to look.
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