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Sci-fi writers have long described terraforming, the process of creating an Earth-like or inhabitable environment on another planet, in their stories. Scientists have themselves proposed terraforming to allow for the long-term colonization of Mars. A common solution for both groups is to release carbon dioxide trapped in the Martian surface to thicken the atmosphere and act as a blanket to warm the planet.
However, Mars does not keep enough carbon dioxide that could practically be put back into the atmosphere to warm Mars, according to a new study sponsored by NASA. Transforming the inhospitable Martian environment into a place that astronauts could explore without vital support is impossible without technology far beyond current capabilities.
Although the current Martian atmosphere is mainly made up of carbon dioxide, it is too thin and cold to support liquid water, an essential ingredient for life. On Mars, the pressure of the atmosphere is less than one percent of the pressure of the Earth's atmosphere. Any liquid water on the surface would evaporate or freeze very quickly.
Proponents of Mars terraforming propose to release gases from various sources on the red planet to thicken the atmosphere and increase the temperature to the point where the liquid water is stable. area. These gases are called "greenhouse gases" for their ability to trap heat and warm the climate.
"Carbon dioxide (CO2) and water vapor (H2O) are the only greenhouse gases likely to be present on Mars Bruce Jakosky of the University of Colorado, Boulder, lead author of the study published in Nature Astronomy July 30.
Although studies examining the possibility of terraforming Mars have been done previously, the new finding benefits from about 20 years of additional space observations from Mars. "These data have provided substantial new information on the history of volatile volatile materials such as CO2 and H2O on the planet, the abundance of volatile substances trapped on and below the surface and the loss of of gas from atmosphere to space "said co-author Christopher Edwards of Northern Arizona University, Flagstaff, Arizona
Researchers analyzed the abundance of carbonaceous minerals and the presence of CO2 in the polar ice using data from Mars Reconnaissance Orbiter from NASA and Mars Odyssey "Our results suggest that there is not enough CO2 remaining on Mars to provide significant greenhouse warming if the gas was to be introduced into the NASA spacecraft MAVEN (Mars Atmosphere and Volatile Evolution), and most of the CO2 gas is not accessible and can not be easily mobilized, which is why it is not possible to terraform Mars using current technology. Jakosky
Although Mars has significant amounts of water ice that could be used to create water vapor, previous analyzes show that water can not provide a significant warming by itself; temperatures do not allow enough water to persist in the form of steam without first having a significant warming by CO2, according to the team. In addition, while other gases such as the introduction of chlorofluorocarbons or other fluorine-based compounds have been proposed to increase the atmospheric temperature, these gases are short-lived and would require processes. large scale manufacturing.
The atmospheric pressure on Mars is about 0.6% of the Earth. With Mars being further away from the Sun, researchers estimate that a CO2 pressure similar to the Earth's total atmospheric pressure is needed to raise temperatures sufficiently to allow stable liquid water. The most accessible source is CO2 in the polar ice caps; it could be vaporized by spreading dust to absorb more solar radiation or by using explosives. However, vaporization of the ice caps would only contribute enough CO2 to double the Martian pressure to 1.2% of the Earth, according to the new analysis.
Another source is the CO2 attached to the dust particles in the Martian soil, which could be heated gas. The researchers estimate that floor heating could provide up to 4% of the required pressure. A third source is carbon enclosed in mineral deposits. With the help of recent observations of NASA mineral deposits, the team estimates that the most plausible amount will produce less than 5% of the required pressure, depending on the magnitude of buried deposits near the surface. Simply using the deposits near the surface would require extensive mining and, after all the CO2 attached to the dust particles, one would have to extract the entire planet to a depth of about 100 meters. Even CO2 trapped in the molecular structures of water ice, if such clathrates existed on Mars, would likely contribute less than 5% of the required pressure, according to the team.
The carbonaceous minerals buried deep in the Martian crust contain enough CO2 to reach the required pressure, but the extent of these deep deposits is unknown, not demonstrated by the orbital data, and recovering them with current technology is extremely energy-intensive, requiring temperatures above 300 degrees Celsius (over 572 degrees Fahrenheit). Low carbon minerals are not abundant enough to contribute significantly to greenhouse warming, and require the same intense treatment.
Although the surface of Mars is inhospitable to the forms of life known today, only the form in the presence of liquid water proves that, in the distant past, the Martian climate bore the water liquid on the surface. But solar radiation and the solar wind can eliminate both the water vapor and the CO2 from the Martian atmosphere. MAVEN and the Mars Express missions of the European Space Agency indicate that the majority of the ancient potentially habitable atmosphere of Mars has been lost in space, washed away by the solar wind and radiation. Of course, once this happens, this water and CO2 are gone forever. Even if this loss has been prevented in one way or another, by allowing the atmosphere to slowly accumulate degassing by geological activity, the current degassing is extremely weak; According to the team, it would take about 10 million years to double the current atmosphere of Mars.
Another idea is to import birds by redirecting comets and asteroids to Mars. However, the team's calculations reveal that several thousand would be needed; still, not very practical.
Taken together, the results indicate that terraforming Mars can not be done with currently available technology. All these efforts must be very far in the future.
Learn more:
Sputtering: How Mars may have lost its atmosphere
More information:
Bruce M. Jakosky et al. Inventory of CO2 available to terraform Mars, Nature Astronomy (2018). DOI: 10.1038 / s41550-018-0529-6
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