The researchers reported the analysis results of data collected by satellites other than Mars in the past few years, which is a cooperative project of the European Space Agency and the Russian Federal Space Agency. This observation shows that there may be more water on Mars than expected, and the presence of hydrogen chloride is detected in the atmosphere of this red planet for the first time.

Illustration: Clouds on Mars. Source: NASA

The results of these two studies are published in Frontier of Science. In the article Transient Hydrogen Chloride in the Atmosphere of Mars, Oleg Kolabolov and his colleagues reported the discovery of hydrogen chloride. This halogen gas was discovered from the observation data collected in April 20 19, which was at the end of summer in the southern hemisphere of Mars. This unique season is notorious for shocking sandstorms, some of which are the size of the whole earth. In 20 18, such a sandstorm ruined the opportunity.

Illustration: Opportunity Mars probe. Source: Hu Zhi

The presence of hydrogen chloride was detected in such an unusually violent sandstorm. Therefore, the research team also speculated that sandstorms may have played a vital role in the existence of halogen gases in the atmosphere of Mars. One possible mechanism is that the water formed by melting ice interacts with sodium chloride (a component of edible salt) and is carried away from the dust by the wind. With the continuous contact and interaction of two molecules, hydrogen chloride is formed. It will exist in the atmosphere for a period of time, or attach to the surface of dust particles and fall to the surface. Future sandstorms will bring it back to the atmosphere.

Another theory holds that hydrogen chloride comes from magmatic activity. Mars is the planet with the highest volcano in the solar system, but as far as we know, these volcanoes are all extinct. Therefore, magmatic activity is impossible. More evidence must be collected before this theory can be used as a feasible mechanism to understand the cause of hydrogen chloride.

Illustration: Volcanoes on Mars. Source: Hu Zhi

The second study focuses on the measurement results of moisture and isotopes in the atmosphere. Chemical elements have different isotopes-each isotope has the same chemical properties, but its physical properties are slightly different because the number of neutrons in the nucleus is not used. Deuterium, the isotope of hydrogen, is the heavier isotope of hydrogen. If you have heard the expression of heavy water related to nuclear power plants, it refers to water molecules composed of deuterium atoms instead of normal hydrogen atoms.

Adjusting the ratio of deuterium to hydrogen in water is a very useful means. On earth, this method is used to confirm that most of the water on our planet does not come from comets. This method is also used to analyze the water cycle of Mars as it orbits the satellite. "D/H, that is, the ratio of deuterium to hydrogen, is our accurate timer-a very powerful measurement method, which can tell us the history and formation of water on Mars and how the loss of water changes with time. Thanks to the Mars Trace Gas Detector, we can better understand and calibrate this timer and detect the potential new water storage on Mars, "explained geronimo Villanueva of Goddard Space Center of NASA, the lead author of this paper.

The research data were collected from April 20 18 to April 20 19, during which many important events were tracked, such as the sandstorm mentioned above and the summer melting of Antarctic ice sheet. The team observed a significant change in isotope ratio. In most cases, it is caused by the evaporation of heavy water, but the research team did not rule out the possibility that there are still other water stores with specific isotope ratios on Mars.

Illustration: The Mars Trace Gas Detector studies the water vapor and its components evaporated from the surface of Mars into space. Source: European Space Agency

Author: Dr. Alfredo Ka Pignetti

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