A new study has found that dust storms on Mars are caused by dramatic energy imbalances between seasons and even between day and night on the Red Planet.
“One of the most interesting findings is that excess energy — more energy is taken in than is produced — may be one of the mechanisms that generates dust storms on Mars,” Ellen Creasey said in a statement. Crecy is a doctoral student at the University of Houston and lead author of the new study.
Mars is known for its dust storms, which tend to occur in the summer in the southern hemisphere of the planet. Often they can grow and cover a significant part of the Red Planet. In January 2022, for example, a dust storm covering nearly twice the size of the United States caused some NASA missions to Mars to be shut down until the storm passed. A global dust storm also ended operations on the Opportunity rover in 2018.
Related: A giant pile of Martian dust created by the wind in this photo taken by the European probe
Planetary scientists have long wondered where the energy that drives these huge storms comes from. Solar heating clearly has something to do with this, given the link between dust storms and southern summers, but the extreme nature of the storms suggests it’s more complex.
Now a new study based primarily on observations from NASA’s now-defunct Mars Global Surveyor (MGS) spacecraft, which operated from 1996 to 2006, and its thermal emission spectrometer. The scientists also included new surface temperature measurements from the Curiosity rover and InSight lander that are still working today. Overall, the researchers found that dust storms are closely related to an imbalance between the amount of solar energy absorbed by Mars and the amount of energy it then re-radiates as heat.
In technical language, this relationship between absorption and re-radiation of heat is called the radiant energy balance. It is different for every planet. The giant planets – Jupiter, Saturn, etc. – are highly unbalanced because their great distance from the Sun means they receive relatively little solar energy, but they re-radiate a lot because they still have a significant amount of internal heat left. left over from their training.
(Image credit: NASA/JPL–Caltech/MSSS)
Earth, on the other hand, has a slight imbalance between 0.2% and 0.4%, meaning that the amount of heat the planet absorbs and the amount it re-radiates back into space is about the same. This is partly due to the ability of our oceans and atmosphere to trap and redistribute heat around the planet.
The prevailing assumption has been that Mars also has a slight imbalance, but the new work shows that this is not the case, which could lead to noticeable differences between the two hemispheres, especially summer in the south and winter in the north.
In 2001, a global dust storm hit Mars, and MGS was ready to study the storm in detail. The spacecraft found that during this violent storm, the energy imbalance between the northern and southern hemispheres of the Red Planet was 15.3%. The extra energy absorbed by the southern hemisphere was more than enough to power huge dust storms.
In addition, the imbalance between day and night becomes even more initial. During the 2001 dust storm, the global average radiated heat decreased by 22% from the global average (111.7 watts per square meter) during the day, but increased by 29% at night. Part of the reason for this imbalance is the presence of heat-absorbing dust suspended in the atmosphere during a storm, the researchers say, but the main reason is the lack of large oceans or a dense atmosphere.
(Image credit: James Gitlin (STScI))
“Mars is not a planet that has any real energy storage mechanisms like we have on Earth,” Chrissy said. “Our large oceans, for example, help balance the climate system.”
Mars once had oceans and a thicker atmosphere, but the oceans dried up over 3 billion years ago and the atmosphere has mostly gone into space. This story implies that the energy imbalance – and the dust storms it causes – are the result of climate change on Mars. Therefore, Mars could provide a glimpse of what’s in store for Earth, either in the event of rampant climate warming or about a billion years into the future, when the aging sun becomes too hot for our planet to have oceans.
Meanwhile, on Mars, dust storm season will begin again in the next few months, with the vernal equinox in the Red Planet’s southern hemisphere taking place in February 2022, according to the Planetary Society. This means that the various rovers and landers on the surface of Mars will not have a dust respite – at least until the next austral winter of 2023.
The study is described in an article published May 16 in the journal Proceedings of the National Academy of Sciences.
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