Scientists: there is not enough CO₂ on Mars to warm up the atmosphere. The explosion of the poles will not help

    The concept of terraforming Mars is a long-standing topic in science fiction literature, and in recent years has been discussed in scientific circles. A new surge of interest in this topic occurred after the announcement of the plans of NASA and individual commercial companies to send colonists to Mars. For example, all the current activities of the private company SpaceX can be considered as preparatory stages for this main goal.

    Creating a long-term colony on Mars implies a plan to terraform the planet to make it fit for life and reduce the risks of colonists associated with lack of oxygen, the threat of solar wind and cosmic radiation. In turn, terraforming involves the restoration of the lost Martian atmosphere and the installation of a magnetic shield or electromagnetic field generator.

    The most difficult stage is the restoration of the atmosphere. Is it possible?

    Two days ago, a scientific article was published in the journal Nature Astronomy , which discussed in detail the topic of Mars terraforming and the main problem — where to get enough carbon dioxide (CO 2 ). The authors are Bruce Jakosky from the Laboratory of Atmospheric and Space Physics at the University of Colorado and Christopher Edwards from the Department of Physics and Astronomy at the University of Northern Arizona. In the photo: a combined image from two devices installed on the Mars Reconnaissance Orbiter. Green color corresponds to naked carbonates in the Nili Fossae graben region on Mars

    Possible approaches to the terraforming of Mars are described in the scientific literature of the past, including the works of Sagan (1971) and Mackay et al. (1991) , pdf . According to Mackay et al., There are two possible approaches:

    1. Increase pressure to a sufficient degree so that people can work without the use of space suits or workwear under pressure. This approach does not require the presence of oxygen in the atmosphere, sufficient for breathing. Colonists can use oxygen masks, which in any case are much more convenient than space suits.
    2. Increasing the concentration of atmospheric greenhouse gas to such an extent that the temperature on Mars will reach a level at which water can be maintained in a liquid state. Higher temperature and stable liquid water will greatly simplify all aspects of operations on Mars.

    Both terraforming approaches require the addition of a significant amount of gas to the atmosphere .

    The only greenhouse gases that can be added to the Martian atmosphere are CO 2 and H 2 O, to ensure the greenhouse effect and the temperature increase. Although some scientists suggest the introduction of other gases, such chlorofluorocarbons, but this option is considered by the authors to be a dubious alternative. Good greenhouse gases CH 4 and H 2 are also absent in large quantities, so the authors consider only CO 2 and H 2 O.

    So, previous calculations of atmospheric warming showed that water alone is not capable of providing significant warming. Temperature will not allow enough vapors to be present in the atmosphere. Therefore, preheating of the atmosphere with CO 2 is required . Only this gas remains. But are there enough reserves of carbon dioxide on Mars to increase the density of the atmosphere and create a greenhouse effect? Inventory of existing stocks has become the main task of researchers.

    Global reserves of carbon dioxide on Mars

    Scientists list existing tanks of non-atmospheric CO 2 and estimate what effect the release of this gas into the atmosphere will have, that is, how much it will increase its density. They also estimated the amount of CO 2 lost, which was previously present on the planet, but dissipated in space under the influence of the solar wind after the sudden disappearance of the protective magnetic field on the planet.

    The authors concluded that there arenot enoughCO 2 reserves on Marsto terraform the planet. Even if all the carbon dioxide from the polar ice is extracted into the atmosphere, the density of the atmosphere will rise to a maximum of 2% of the earth's.

    Recall that Ilon Mask had previously studied this problem and proposed to blow up the Martian poles in order to free up the necessary amount of CO 2 and H 2 O. According to scientists, this method will not help. Even if we assume there the maximum possible amount of CO 2 and completely melt all the glaciers, the density of the atmosphere will still increase to no more than 15% of the earth's.

    Theoretically, CO 2 can be obtained by heating the minerals in the Martian crust. Images of grabens in Nili Fossae indicate a fairly large number of carbonates at depth. Scientists believe that this can increase the density of the atmosphere to the earth. But for this you need:

    • completely melt the polar caps and glaciers;
    • clear the entire surface of the planet, exposing the minerals;
    • Heat all carbonates in the Martian crust so that they release carbon dioxide (and continue to heat them constantly so that they do not absorb gas back.

    In practice, the authors believe, it is unlikely that we will succeed in using the Martian CO 2 to increase the density of the atmosphere by more than 1.5–2% of the Earth’s.

    The scientific article was published on July 30, 2018 in the journal Nature Astronomy (doi: 10.1038 / s41550-018-0529-6, pdf ).

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