The global Mars dust storm in the summer of 2018 provides unprecedented learning opportunities. For the first time, humans have owned eight spacecraft orbiting Mars or roaming the surface of Mars.

The global Mars dust storm in the summer of 2018 provides unprecedented learning opportunities. For the first time, humans have owned eight spacecraft orbiting Mars or roaming the surface of Mars. This is the largest robotic explorer ever observed a global outbreak of sandstorms.

Scientists around the world are still analyzing a large amount of data, but preliminary reports include insights on how large-scale sandstorms may affect ancient Martian water, wind and climate, and how they affect future weather and solar energy.

"Curiosity"'s mast camera shot between SOL2075 and SOL2170 on Mars shows a progressive sandstorm shot between June 8, 2018 and September 13, 2018.

Martian dust storms are common, especially in spring and summer in the southern hemisphere of Mars. They tend to last for a few days and can cover areas of the planet that are about the size of the United States. But the dust storms surrounding the planet are unpredictable and sometimes last for several months. Why?

Scott Guzewich, an atmospheric scientist at NASA’s Goddard Space Flight Center, is also the lead researcher in NASA’s sandstorm investigation. "We still don't know what drives this change, but the 2018 storm provides another data point," he said. "

NASA first saw a global sandstorm on Mars in 1971, when the Mariner 9 spacecraft -- the first spacecraft orbiting another planet, arrived at a red planet engulfed in dust. Since then, we have witnessed the global storm on Mars in 1977, 1982, 1994, 2001, 2007 and 2018.

During the recent global dust storm on Mars, we have seen three things from space and the ground that have helped solve some unsolved problems and exposed new problems:

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

Will global sandstorms 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. Dried 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, believes that the global sandstorm on Mars may give us an explanation.

Vilanova collaborated with colleagues from the European Space Agency and the Roscosmos Space Agency to confirm that a powerful global dust storm appears to raise water vapor from a typical altitude of 20 kilometers above the surface of Mars to a higher altitude of at least 80 kilometers. A similar phenomenon was observed in 2007 by NASA's Mars Reconnaissance Orbiter.

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

Vilanua and his colleagues speculate that at higher altitudes, Mars' atmosphere is particularly thin, and solar radiation can easily penetrate water molecules and blow their constituent elements into space. Villanueva has been pieced together the history of water on Mars throughout his career, and he believes that when it comes to bringing water to higher parts of the atmosphere, it is more likely to be blown away.

On April 10, 2019, Villanueva and his colleagues reported in the peer-reviewed journal Nature that they found evidence of water vapor subsidence using Extramars tracking gas orbiter on Mars. The orbiter measured water molecules at different altitudes before and after the 2018 storm. Scientists have seen for the first time that all types of water molecules (light and heavy) reach the "escape zone" of the upper atmosphere, an important insight into how water disappears from Mars.Now, Villanueva said scientists will have to take into account this new information in their predictions about how much water flowed on ancient Mars and how long it would take to disappear.

The surface of Mars is covered by the sand that is constantly moving from the wind of this planet. This creates an evolving desert landscape with diverse sand dunes. Mars is full of loose sand dunes, ranging from a few meters to higher than some of the tallest skyscrapers on Earth. Images taken by a high-resolution imaging scientific equipment (HiRISE) instrument on NASA's Mars Reconnaissance Orbiter allow scientists to study Mars' dunes to unprecedented detail. Enhanced color images taken from orbit reveal their shape, composition, and motion characteristics over time, providing clues to understanding the dynamic atmosphere and current climate of Mars.

Martian global dust storm does not appear to have changed the shape of Martian dunes

For scientists tracking the distance between the dunes moving on the surface, Martian global dust storm provides key evidence for them to investigate the wind direction on the red planet. Scientists once believed that only strong winds during global dust storms could move large areas of sand dunes on Mars, because Mars' ultra-thin atmosphere makes the wind at 160 kilometers per hour feel like a breeze. However, for decades, images from orbiters and landers have shown that sand on Mars has been moving, meaning it can move without strong gusts of wind. This was a surprise for the researchers.

Now scientists can finally observe a global sandstorm on Mars from the ground through the NASA's " Curiosity " probe, and they noticed another surprising feature of the Martian wind: strong winds do not seem to move more sand than normal. Mariah Baker of Johns Hopkins University, helped track changes in Martian sand patterns. She thinks this adds to the whole mystery of how Martian upwinds move.

Ongoing analysis of the entire Mars will reveal whether the Gael crater where Curiosity is located is unique. In addition, scientists pointed out that the wind inside the Gael crater may behave differently.

If the dunes on Mars don't move too much during the storm, there might be a good reason: the wind that rotates dust in the atmosphere may not be the same as the wind on the surface.

Some scientists believe that when dust is brought into the atmosphere during a global storm on Mars, preventing sunlight from reaching the ground, it shuts down the wind-generating process near the ground, which is normally caused by temperature fluctuations between the air and the ground.

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

We can look at the wind-like sandstone on the ground and see the sand dunes that are moving now. This shows how the situation here was billions of years ago when these dunes were moving, and now they are fixed in the rock record again?

In 2017, the navigation camera on NASA's Curiosity Mars rover observed several cyclones , which carried Martian dust across the Gaelic crater. Sandstorms are caused by the sunlight warms the ground and causes the air convection to rise.

Dust whirlwind is a kind of rotating air and dust that is common on Mars. When the hot air on the surface rises, they form, forming a whirlwind-forming airflow. These cyclones are useful when cleaning up dust from solar spacecraft panels. Therefore, it is important to understand how often they occur.

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