Enlightenment of Martian sandstorm

The global Martian sandstorm in the summer of 20 18 provided unprecedented learning opportunities. For the first time, humans have eight spacecraft orbiting or roaming on the surface of Mars. This is the largest robot explorer who has ever observed the global sandstorm outbreak.

Scientists around the world are still analyzing a lot of data, but the preliminary report includes opinions on how large-scale sandstorms may affect the water, wind and climate of ancient Mars, and how they will affect the future weather and solar energy.

The photos taken by Curiosity's mast camera between SOL2075 and SOL2 170 on Mars show the advancing sandstorm, which was taken between June 8, 20 18 and September 20 18 13.

Sandstorms on Mars are very common, especially in spring and summer in the southern hemisphere of Mars. They usually last for a few days and can cover an area the size of the United States on earth. But sandstorms on the earth are unpredictable, sometimes lasting for months. Why?

Scott Guzewich is an atmospheric scientist at NASA Goddard Space Flight Center and the principal investigator of NASA's sandstorm investigation. He said: "We still don't know what is driving this change, but the storm of 20 18 provides another data point."

NASA first saw a global sandstorm on Mars in 197 1 year, when Mariner 9, the first spacecraft orbiting another planet, arrived at a red planet swallowed by dust. Since then, we have witnessed the global storms on Mars in 1977, 1982, 1994, 200 1, 2007 and 20 18.

During the recent global sandstorm on Mars, we saw three things from space and on the ground, which helped to solve some outstanding problems and exposed new ones:

Hydrogen atoms escape from the upper atmosphere of Mars, while water containing heavy hydrogen (deuterium) is still trapped on Mars. The escape of hydrogen helped Mars change from a wet planet 4.5 billion years ago to a dry world today.

Will the global sandstorm blow away the water from Mars?

Scientists have found a lot of evidence that Mars had rivers, lakes and even oceans billions of years ago. Dry riverbeds, ancient coastlines and salty surface chemistry are all clues. But why did most of the water disappear? How did they disappear? Geronimo Villanueva, a Mars water expert at NASA Goddard Space Center, thinks that the global sandstorm on Mars may give us an explanation.

Villanueva, in cooperation with colleagues from the European Space Agency and the Russian Space Agency, confirmed that powerful global sandstorms seem to lift water vapor from a typical height of 20 kilometers above the surface of Mars to a higher height of at least 80 kilometers. A similar phenomenon was observed by NASA's Mars Reconnaissance Orbiter in 2007.

By injecting water into the upper atmosphere, global sandstorms on Mars may interfere with the water circulation on Mars, preventing water from condensing and falling back to the surface. On the earth, water falls in the form of rain and snow. Billions of years ago, the same process may have existed on Mars.

Villanueva and his colleagues speculate that at higher altitudes, the atmosphere of Mars is particularly thin, and solar radiation can easily penetrate water molecules and blow their constituent elements into space. Villanueva has been piecing together the history of water on Mars in his career. He thinks that when water is brought to the upper atmosphere, it is easier to be blown away.

In April 19, 10, Villanueva and his colleagues reported in the peer-reviewed journal Nature that they found evidence of water vapor fading by using exoMars on Mars to track the gas orbiter. The orbiter measured water molecules at different heights before and after the 20 18 storm. For the first time, scientists saw that all types of water molecules (light and heavy) reached the "escape zone" of the upper atmosphere, which was an important insight into how water disappeared from Mars. Now, Villanueva said, scientists will have to take these new information into account in their predictions, that is, how much water flowed on ancient Mars and how long it would take to disappear.

The surface of Mars is covered with sand, which keeps moving with the Martian wind. This has created an ever-changing desert landscape and diverse sand dunes. Mars is full of loose sand dunes, ranging from a few meters high to higher than some of the tallest skyscrapers on earth. The images taken by the High Resolution Imaging Science Equipment (HiRISE) on NASA's Mars Reconnaissance Orbiter enable scientists to study the dunes of Mars in unprecedented detail. The enhanced color images obtained from orbit reveal their shapes, compositions and movement characteristics with time, which provides clues for understanding the dynamic atmosphere and current climate of Mars.

Global sandstorms on Mars do not seem to have significantly changed the shape of sand dunes on Mars.

For scientists who track the movement distance of sand dunes on the surface, the global sandstorm on Mars provides key evidence for them to investigate the wind direction on this red planet. Scientists once thought that only the strong winds during the global sandstorm could move a large area of sand dunes on Mars, because the ultra-thin atmosphere of Mars made the wind per hour 160 km feel like a breeze. However, for decades, images from orbiters and landers have shown that the sand on Mars has been moving, which means it can move without strong gusts. This is a surprise for the researchers.

Now, scientists can finally observe the global sandstorm on Mars from the ground through NASA's Curiosity probe. They have noticed another surprising feature of the Martian wind: strong winds don't seem to take away more sand than usual. MariahBaker, from Johns Hopkins University, helps track the changes in the Martian sand pattern. She thinks this adds to the whole mystery of how the wind moves on Mars.

The ongoing analysis of the entire Mars will reveal whether the Gaelic Crater where Curiosity is located is unique. In addition, scientists point out that the wind in Gael crater may behave differently.

If the dunes on Mars don't move much during the storm, there may be a good reason: the wind that spins dust in the atmosphere may be different from the wind on the surface.

Some scientists believe that when dust is brought into the atmosphere in the global storm on Mars and sunlight is prevented from reaching the ground, it will shut down the wind generation process near the ground, which is usually caused by temperature fluctuation between the air and the ground.

Whatever the reason, understanding the behavior of sand dunes today will help us reveal the ancient climate of Mars.

We can look at the aeolian sandstone on the ground and the sand dunes that are moving now, and we can see what happened when these sand dunes moved billions of years ago. They are fixed on rock records. What's going on here now?

In 20 17, the navigation camera on NASA's Curiosity Mars probe observed several cyclones, which carried Martian dust through Gael crater. Sandstorms are caused by sunlight heating the ground and promoting air convection.

Dust cyclone is a kind of rotating air and dust, which is very common on Mars. When the hot air on the surface rises, they form, forming a whirlwind airflow. These cyclones are very useful in cleaning the dust on the panels of solar spacecraft. Therefore, it is important to know their frequency.

Guzevich said that understanding the impact of global storms on Mars on dust cyclones is very important for planning how to power equipment in the future mission to mars.