Mars is at the extreme of salt water stability. And only the combination of the most favorable environmental conditions and the salt with the lowest eutectic temperature could stabilize brine, at least temporarily, on the surface of Mars, one researcher says. new research Published in Proceedings of the National Academy of Sciences.
This image of an impact crater in the Sirenum Fossai region of Mars was taken by NASA's Mars Reconnaissance rover on March 30, 2015. The crater is approximately 3,300 feet (1 km) wide and appears to be relatively recent due to its sharp edges and wells. -Stored emissions. The steep inner slopes are carved by canyons and contain slope lines that may recur on the equator-facing slopes. Image credit: NASA / JPL / University of Arizona / Alfred McEwen.
Liquid water is an important prerequisite for a habitable planet. However, the combination of Mars' low temperatures, atmospheric pressure, and water vapor pressure means that any liquid water found on Mars would likely freeze, boil, or evaporate quickly, making it unlikely that Mars exists. .
However, paleontologists continue to insist that liquid water exists on Mars.
Of particular interest is the discovery of seasonal black stripes called repeat slope lines.
These features appear in some places on Mars when temperatures rise above -23 degrees Celsius (-10 degrees Fahrenheit) and disappear when it gets colder.
They are often described as possibly being associated with liquid water.
The new study puts a damper on the idea that liquid water is likely to be found soon in Mars' recurring slopes, permafrost, or salt water.
“If we look closely at RSL, its behavior is consistent with a sand or dust flow, and water is not required for RSL formation,” said lead author Dr. Vincent Chevrier, a researcher at the University of Arkansas. said.
Other researchers believe that brine, a highly salty solution like Earth's oceans, may hold the key to finding liquid water on Mars.
Salt water can freeze at much lower temperatures, and Mars is rich in salt.
Among these salts, perchlorate appears to be the most promising because of its extremely low eutectic temperature (the temperature at which the melting point of the mixture is lower than that of the single components).
For example, calcium perchlorate brine freezes at -75 degrees Celsius (-14 degrees Fahrenheit), but the average surface temperature near the equator of Mars is -50 degrees Celsius (-58 degrees Fahrenheit), so theoretically This suggests that there may be zones where calcium coagulates. Perchlorate water can remain liquid, especially underground.
Dr. Chevrier and his colleague, Dr. Rachel Srank of the Lunar and Planetary Institute, then considered all the arguments for and against brine that could form a stable liquid.
“A variety of limiting factors, including the relatively small amount of most promising salts, water vapor pressure, and ice position, strongly limit the amount of brine present at the surface and in the shallow subsurface,” the researchers said. Ta.
“And even if saline waters formed, they would still remain uninhabitable by terrestrial standards.”
“Despite these drawbacks and limitations, there is always a possibility that Martian life adapted to these salt waters and some terrestrial life could survive in them. This is a planetary protection consideration because there is a possibility that
“Therefore, detecting brine in situ remains a key objective for Mars exploration.”
The next hurdles ahead, the authors say, are improving the equipment needed to detect small amounts of brine, better identifying the best places to look for brine, and conducting more experiments under Martian conditions. It is suggested that this is to enable room measurements to be carried out.
“Despite our best efforts to prove otherwise, Mars remains a cold, dry, and completely uninhabitable desert,” Chevrier said.
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Vincent F. Chevrier and Rachel A. Slank. 2024. The elusive nature of liquid brine on Mars. PNAS 121 (52): e2321067121;doi: 10.1073/pnas.2321067121
Source: www.sci.news
