Mars: Dust storm is now global

For the first time since 2007, the Red Planet experiences a planet-spanning storm

Dust everywhere: This shot of the camera of the Mars rover Curiosity shows the obscurity of the sky in the Gale Crater. © NASA
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The time has come: On Mars, a global dust storm is raging - for the first time since 2007. The weather phenomenon that began in late May over the Arabia Terra region has steadily expanded over the entire planet in recent weeks, NASA reports. Meanwhile, even on the opposite side of Mars, the sky is covered by dust veils. For planetary research, this is a unique opportunity to explore this phenomenon in more detail.

The Mars Rover Opportunity hit it first: Already in early June, its sensors registered a rapid dimming of the sky. The so-called Tau value, which indicates the obfuscation of the atmosphere, was already at 10.8 on 14 June - a record. It had not been so dark even at the last global dust storm of 2007. For the Rover powered primarily by solar energy, this meant a compulsory break.

But so far it was unclear whether this storm would expand into a planet-spanning phenomenon. Because regional dust storms are nothing unusual in the Martian spring and summer and planetary researchers have falsely speculated on a global expansion several times - most recently in the fall of 2016. One of the reasons for this was that planet-spanning storms occur on the Red Planet about every three to five years the next long overdue.

Once around the whole planet

Now the time has come: NASA has officially classified the current dust storm on Mars as global. While the Opportunity Rover has long since been shut down for security reasons, the Rover Curiosity, which is located on the other side of Mars, continues to send weather data and images of the Red Planet. And now they also show a drastic increase in dust in the atmosphere at its location in the Gale Crater.

Selfportrait of Curiosity from the 20th of June. The Marshimmel is already filled with reddish dust. © NASA / JPL-Caltech / MSSS

The tau scores at the Curiosity site have more than doubled within a few days, NASA reports. Currently, the rover measures values ​​of more than 8 higher than ever before in its mission time. At the same time, pictures of the mast camera show a clearly veiled and darkening sky. The veil is six to eight times thicker than it was in the Martian year, NASA said. display

Curiosity keeps going

But despite the planet-spanning dust storm, the Curiosity Rover can continue to work for now sammeln collecting valuable data on this Martian weather phenomenon. Because he gains his energy from a thermoelectric radioisotope generator and is therefore independent of the sunlight. Although the fine pebble dust poses dangers because it can disturb sensitive camera optics and electronics, so far the NASA engineers give the all-clear.

This animation from images of Curiosity shows the increasing concealment of the Marsatmoph re. NASA

In addition to the instruments of Curiosity, all sensors of the Mars orbital probes are now also aimed at the dust storm. From the data collected, scientists hope to find out, among other things, why some storms extend to the entire planet and others do not. "We have no idea yet, " says Scott Guzewich of NASA's Goddard Space Flight Center in Greenbelt.

So far, it is only known that the regional dust storms on Mars, especially during the spring and summer of southern hemisphere, are called. Then the planet is the closest to the sun and the atmosphere is heated up relatively high. The resulting temperature differences become driving forces for the storms and these large amounts of fine martensite dust in the height. The dust clouds can reach up to 60 kilometers in such a storm.

The solar heat also causes carbon dioxide ice to evaporate on the polar ice cap and the released CO2 condenses the Martian atmosphere. This strengthens the power of the storm and helps to keep the fine dust particles in the air longer, as the NASA researchers explain. However, most of these dust storms remained regional and recover after only a few weeks. Why this is not the case every few years, could perhaps show the current storm.

(NASA, 21.06.2018 - NPO)