Despite having radically different atmospheres, Mars and Earth appear to have similar cloud patterns, suggesting that the features may form in much the same way.
Observations obtained by the European Space Agency (ESA) Mars Express spacecraft and NASA Mars Reconnaissance Orbiter, was unexpected. Perhaps most surprising to scientists is that the clouds observed over the dry, arid atmosphere of Mars They are similar to those found in very different environments on Earth.
When thinking of a Mars-like atmosphere a landMars Express project scientist Colin Wilson said in a statement statement (Opens in a new tab). “It is quite unexpected, then, that by tracing the chaotic movement of dust storms, parallels can be drawn with processes occurring in the humid and hot equatorial regions that are not quite Mars-like.”
Related: NASA’s Curiosity rover is detecting colorful, bizarre clouds on Mars
For the research, scientists looked at two dust storms that occurred near the north pole of Mars in the spring of 2019. To monitor the storms from orbit around the Red Planet, they viewed images taken by Mars Express’ Visual Monitoring Camera (VMC). High Resolution Stereo Camera (HRSC) and MRO’s Mars Color Imager.
VMC images show the storms growing and then disappearing in a cycle showing common features and shapes as they recur over days. Spiral shapes with lengths between about 1,600 and 3,200 miles (1,000 to 2,000 km) are visible in HRSC’s broader-vision images. These spirals appear to form in the same ways as extratropical cyclones form at mid-latitudes and polar latitudes on Earth.
The images also reveal that dust storms on Mars are composed of smaller cloud cells spaced regularly apart like pebbles, forming a garden path-like texture also seen in clouds above Earth.
These patterns are created when hot air rises and cooler, denser air falls in cell-like units—a phenomenon called closed-cell convection. The researchers explained that as hot air rises through the center of these cells, cooler air falls through the “tracks” that form in the gaps between individual cells.
On Earth, this convection causes clouds to form because the rising hot air contains water, which then condenses and falls as rain. However, in Mars’ dry, arid environment, rising plumes of hot air carry dust. As the air cools and sinks, it holds less dust. As a result, cells form on Mars in the familiar grain pattern seen in clouds above Earth, albeit with a dusty rather than watery composition.
Dust cells seen above the surface of Mars are useful as a measuring tool, as their motion in the image sequence allows scientists to measure Martian wind speeds. This operation revealed wind gusts of up to 87 mph (140 km/h); These high-speed winds cause the convection cells to elongate in the direction of the wind.
The lengths of shadows in images captured with the VMC, when measured and compared to the known position of the sunalso revealed the height of the Martian dust clouds — about 4 to 7 miles (6 to 11 km) wide — and showed that the convention cells are 12 to 25 miles (20 to 40 km) wide.
“Despite the unpredictable behavior of dust storms on Mars and the strong winds that accompany them, we have seen that, given their complexity, organized structures such as fronts and cellular convection patterns can emerge,” Agustín Sánchez-Livaga, science team leader at VMC and lead author of the study, said. in the statement.
Earth and Mars are not the only two places in the world Solar System Where this cellular load is seen; ESA’s Venus Express A spacecraft has detected similar patterns in venusian clouds.
“Our work on Mars’ dry convection is another example of the value of comparative studies of similar phenomena occurring in planetary atmospheres in order to better understand the mechanisms behind them under different conditions and environments,” said Sanchez-Livaga.
This insight into the Martian clouds gives planetary scientists a better understanding of the dynamics of the Martian atmosphere. Furthermore, knowledge of Martian dust storms could help inform future missions to the Red Planet.
Dust storms can block the light from the sun needed to power the solar cells of the robotic rover exploring the surface of Mars. The potentially harmful effects of dust storms on Mars were demonstrated in 2018, when a planet-wide event blocked sunlight and coated Opportunity’s solar panels with dust, finish its mission.
Predicting the development of such dust storms could protect solar-powered missions from these powerful natural events and even help future Mars astronauts deal with dust storms.
The team’s research was published Tuesday (November 15) in the journal Icarus.
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