The search for liquid water on Mars in 2015 has fueled hopes that signs of life are lurking somewhere on the red planet. But in practice, scientists have more or less ignored whether these specific waters had anything to do with life today. The only way that water could exist as a liquid on such a cold planet is when it is saturated in salt, which lowers the temperatures below freezing. Salty water is not considered an ideal place for life to emerge and develop.
But all this water could be worth another look. New findings released in Nature Geoscience on Monday suggest that these pools could contain more oxygen than we had ever imagined ̵
"These are really great observations They are opening up new opportunities for life on Mars, especially on the early Earth," said Lewis Ward, a geobiologist at Harvard University and co-author of the new study.
It is believed that the Martian atmosphere contains 0.145 percent oxygen compared to the nearly 21 percent that swirl around the Earth. This number does not necessarily kill Martian dreams; After all, the first life forms on earth did not have access to free oxygen in the first few billion years (the evolution of photosynthesis has determined that for us). But oxygen allows an organism to use much larger amounts of energy so that a lack of free oxygen restricts the hopes for life that is at least a few steps above the baseline level.
The right conditions, however, could allow large amounts of oxygen to dissolve into these Mars reserves, especially since oxygen dissolves better in water at lower temperatures. Unfortunately, "no one has ever thought about how much oxygen could be present in liquid water on Mars because we did not have any evidence that oxygen really did matter," says Ward. "This is the first attempt to really understand how much oxygen it could be today."
The study depends on the presence of manganese oxide on the Martian surface. On Earth, there were signs of manganese oxide minerals around the time that oxygen had accumulated in the atmosphere about 2.5 billion years ago. Unlike iron (which is responsible for the crimson appearance of the red planet), manganese is quite hard to oxidize, and the only way we find that oxidation takes place on Earth is either very slowly or with the help of biology.
But in 2014, the Curiosity Rover found very concentrated manganese deposits on Mars, causing Ward and his colleagues to wonder if they contained the oxygen needed to pump the material near aqueous environments oxidize. Manganese oxidation is quite solid (though certainly not exclusive) associated with biological activity. The study could be considered a Matryoshka questionnaire: First, how much oxygen do you need to oxidize manganese? Is this concentration of oxygen present in Marsh water? And finally, at the heart of the study: Does this amount of oxygen increase the possibility that oxygen-breathing organisms exist on Mars?
"If there is enough oxygen to do chemically useful work in the oxidation of manganese, this indicates that there is enough work to do biologically meaningful work," says Ward.
The new study has encouraging answers to these questions. The team developed models for six different salt concentrations, which can hold liquid temperatures from -20 ° C to about 80 ° Fahrenheit, and takes into account various pressures found on the planet. The models say the salty liquid is more than capable of capturing the deplorable amounts of oxygen scattered across the Martian surface. In fact, the models suggest that there is more oxygen on Mars today than on Earth when photosynthesis began, "Ward says, suggesting that there may be enough [oxygen] to metabolize microorganisms "For aerobes that use oxygen to eat carbon for energy," it turns out that there is actually a lot of oxygen in these salt solutions to support bacteria and bacteria. Some sponges do just that. "The results also suggest suggest that there is enough oxygen on the surface and underground of Mars to support energy from other sources such as methane and iron.
Sponges are a particularly useful model when you think about what these environments could survive "Sponges are one of the earliest types of animals that evolve," says Ward, who are simple filter-feeders who survive bacteria n can survive and survive in very simple ecosystems. Ward admits, "To study the potential of life on Mars and other planets, we'd better think only of microbes," but the attenuated oxygen requirements of sponges are interesting when we think about what could
Ward and his team hoping that the results will be a first step in helping scientists create a map of regions on Mars that are likely to support the largest concentrations of oxygen based on temperature and air pressure and overlay with another map illustrates the planet's largest points of hydrogen and methane that could be consumed for energy. "We could actually point to places on Mars that have the best chance of discovering biological activity" and potential biomass, he says. The study could also help us to shed light on the potential of other worlds, such as Europe, to promote life.
Of course, there are reasons to be wary of the implications of the study because it relies on computer modeling rather than direct observations. It will be difficult to confirm the results – not only on Mars, but also here on Earth, where scientists have not yet been able to conduct controlled laboratory experiments that yield good measurements of oxygen solubility in very cold brines. On Mars itself, we need to be able to study sols that are sufficiently in contact with the atmosphere to facilitate gas exchange and to dissolve oxygen in the air in the water.
Jonathan Toner, astrobiologist at the University of Washington. The study did not do a good job and showed that the oxygen content in the Marine environments could not be a limiting factor for life, and also found it interesting to see a discussion of atmospheric interactions with the sols also have implications beyond habitability, "he says, yet he emphasizes that high oxygen levels here only with extremely high salinity levels combined with average temperatures of -67 degrees Fahrenheit, and you have conditions that are not known to support life on earth, life does not need just one factor, like one Oxygen supply, but a whole series of factors that all exist simultaneously: "If life exists on today's Mars," it would have to be extremely low Nutrient Reservoirs, Low Temperatures, and It is well known that a high salt content, which is greater than anything that lives on Earth tolerates. "
So far, few studies have suggested that we could dare to dream of such complex forms of life on Mars, but with each passing year, Mars proves more enticing than we predicted After living on the red planet, there's a lot to do on their to-do lists.