This article was originally published Conversation. The publication contributed to an article on Space.com Expert voices: op-ed and insight.
David Rothry, Professor of Planetary Geosciences, The Open University
Venus can capture life up to 0 km above its surface, we learned a few weeks ago. Now a new paper published in Nature Astronomy reveals that the best place for life on Mars could be more than a kilometer Below Its surface, where a complete network of subglacial lakes has been discovered.
Mars has not always been as cold and dry as it is now. There are plenty of signs that in the distant past water flowed over its surface, but today you also struggle to find any crevices that can make a damp call.
There is still plenty of water on Mars today, but it is virtually all frozen, so not much use for life. Signs of liquid water surface are depressingly rare even in places where the afternoon temperature cools. This is because the atmospheric pressure on Mars is too low to limit water in its liquid state, so when heated, ice usually evaporates.
Lakes under ice
It seems that the most suitable place for liquid water on Mars is under its huge South Polar ice cap. On Earth, the search for such lakes began in the 1970s in Antarctica, where about 400 people are now known. Most of them have been detected by “radio echo sounding” (essentially radar), in which the devices of a survey aircraft emit radio pulses.
Part of the signal is reflected back from the ice surface, but some is reflected from below – especially where there is a boundary between ice and the underlying liquid water. The largest subglacial lake in Antarctica is Lake Vostok – which is 240 km long. Long, 50 km. Width and depth of hundreds of meters – which is 4 km from the surface. Located below.
Signs of similar lakes beneath Mars’ south polar ice cap were first indicated by radar reflections 1.5 km below the ice surface in an area called Ultimi Scopuli. This was discovered between May 2012 and December 2015 by Marsis (Mars Advanced Radar for Subsurface and Ionosphere Sounding), an instrument orbiting the planet since 2003 by the European Space Agency’s Mars Express.
A new study of Mercedes data using signal processing techniques that takes into account both the intensity and sharpness (“intensity”) of the reflection shows that the previously discovered region actually marks the top of the liquid body. This is the Ultimate Skop Puli subglacial lake, and there also seem to be small patches of fluid covered by the survey in an area of 250 km by 300 km. The authors suggest that liquid bodies contain hypersalin solutions, in which high concentrations of salt are dissolved in water.
They point out that salts of calcium, magnesium, sodium, and potassium are thought to be ubiquitous in longitudinal soils, and may help explain how subglacial lakes on Mars can remain liquid despite the low temperatures at the base of the melted ice cap. . The weight of the excess ice will provide the pressure needed to keep the water in a liquid state rather than turning it towards steam.
Life in subglacial lakes?
Lake Sts is considered a potential habitat for life that has been separated from the Earth’s surface for millions of years, and as an analogue to the proposed atmosphere inhabited by microbes (and possibly more complex organisms) in international oceans such as Jupiter’s Moon. Europa and Saturn’s Enceladus.
Although hypersalin water will allow microorganisms to live below the south polar cap of Mars, they will not be able to survive without some kind of energy source (food) source. Chemical reactions between water and stone release a little energy, but probably not enough; If there is an occasional volcanic eruption, or at least a hot spring, it will help to feed the lake.
read more: What on earth lives in a freshwater lake on Mars? An expert explains
Unlike Europa and Enceladus, we have no evidence of this on Mars. Although the new findings make Mars even more interesting than before, they have not increased its ranking in the list of solar system groups, the probability of life is much higher.
That said, saltwater can act as a defense chamber – it helps find alien organisms that are now extinct but once came to Mars from other parts of the solar system.
This article is republished from the talk under the Creative Commons license. Read the original article.
Expert Voices Follow all of its issues and controversies – and be part of the discussion – Ongoing Facebook And Twitter. The opinions expressed are those of the author and do not reflect the views of the publisher.
