Mars is often considered to be the planet most similar to the Earth. Earth however, is capable of supporting life, Mars on the other hand could not. There was once a time when it was warmer and wetter and could support life. Exploring life on Earth shows us that bacteria known as extremophiles can live in the most harsh conditions on Earth, it may just be possible that there are places on Mars that could also support these hardy forms of life. A new paper explores that possibility by studying the most extreme Earth-based bacteria that could survive under ground on Mars.
Mars, often referred to as the “Red Planet” because of its reddish appearance. It’s the fourth planet from the Sun orbiting at an average distance of 228 million kilometres. It has a thin atmosphere, made up mostly of carbon dioxide with surface temperatures from about -125°C to 20°C. Mars has some fascinating geological features including the largest volcano in the solar system; Olympus Mons, and a vast canyon system; Valles Marineris. Unlike Earth, Mars has two moons Phobos and Deimos which are thought to be captured asteroids.
The atmosphere of Mars is thin and, whilst carbon dioxide is the main component, there is also methane in small amounts, around 0.00003% of the whole. It’s origins in the Martian atmosphere are not fully understood and it may be that it is there as a result of biological processes such as the metabolism of microbes. It could also be there due to geological processes such as volcanic eruptions. The presence of methane has also excited researchers who have been exploring whether Mars could in anyway support more extreme forms of primitive life.
In a paper recently authored by Butturini A from the University of Barcelona and team, they explore the Martian environment and its suitability to support extremophiles known as methanogens (from the Methanobacteriaceae family.) These primitive forms of bacteria are found in some of the most inhospitable regions of Earth. They have been found thriving in the hot groundwater of Lidy Hot Springs in Idaho, and are based upon methane biology. It raises an interesting possibility that areas of Mars could provide a habitat for them.
The conditions on the surface of Mars are well understood. With high energy radiation from cosmic rays and solar radiation, along with dry and cold conditions and a high temperature differential between day and night, the surface is not conducive to any known forms of life. Look a little deeper however and the conditions seem a little more favourable. Lower levels on Mars however may be more habitable than the surface. A few metres underground and the surface material offers protection from the incoming radiation. Temperatures lower down would be higher and less variable too giving the possibility that liquid water may be present. It has already been seen that subsurface water has in some areas of Mars found its way to the surface only to evaporate when met with the surface conditions. With the presence of salt too the subsurface water can be present as liquid at a lower temperature.
The team conclude that methanogens seem to be thriving in hostile environments on Earth which are analogous to some areas of Mars. They identify the southern area of Acidalia Planitia as somewhere to search due to the high levels of radiogenic heat producing elements which suggest subsurface water may be present. It raises the interesting possibility that, theoretically at least, primitive life could exist on Mars, even today, we just need to find it!
Source: Potential habitability of present-day Mars subsurface for terrestrial-like methanogens
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