Perhaps one of the most interesting puzzles,associated with Mars, is the secret of the disappearance of water from the surface of the Red Planet. Today, thanks to the rovers working on the surface of the planet, as well as the orbiters, scientists are almost certain that Mars was once much wetter. Moreover, there are suspicions that almost 2/3 of its surface in the distant past could cover a giant ocean. So where did all the water go? According to the findings of a new study published in the journal Nature, global dust storms that descend onto the Red Planet with an enviable consistency can be the culprits, or more precisely the culprits of this disappearance.
Dust storms are quite common for Mars. One of them, relatively recently, “buried” one of the mars rovers of the NASA aerospace agency Opportunity. They have a seasonal nature, and most often begin in spring and summer, in the southern hemisphere of the planet. Lasts, as a rule, for several days, covering an area equal in size to the United States. In addition, global dust storms covering the entire sky of Mars are descending on the planet with periodicity.
In mid-July 2018, the space telescopeNASA Hubble observed Mars, just 13 days before the planet got as close to Earth as possible. If, as part of previous observations, the surface of the Red Planet was clearly visible on the images, then in the new images, scientists could only see a giant storm that completely engulfed Mars. Global dust storms of Mars can last for weeks or even months. Most often begin when spring or summer begins in the southern hemisphere. At this point, Mars is closest to the Sun, which maximizes the temperature on its surface and leads to the appearance of strong solar winds.
Global dust storms on Mars behavefar less predictable than more compact, seasonal storms. They occur every few years, cover the entire planet and can last for months. During the last such storm, which hit in June 2018 and lasted until September, six orbital and two ground-based spacecraft observed a catastrophic Martian weather phenomenon. Unfortunately, one of them, the Opportunity Mars rover could not survive the last hurricane.
Image obtained by the rover "Curiosity" onone of the sites on which the soil of the Red Planet was drilled. The photo on the left was taken during the usual Martian day, before the beginning of the global dust storm of 2018. The image on the left was made by the device when the dust storm fully gained its strength.
The question is, what causes these massive storms? What role do they play in the Martian climate and how do they affect the atmosphere of the Red Planet? Are they responsible for the fact that Mars has lost its water? NASA aerospace agency experts have been trying to find answers to these puzzles for decades.
First, the quick response to one frequently askedquestion: how did the Curiosity rover manage to survive the global dust storm, and Opportunity "died a brave one"? The fact is that Opportunity worked on the basis of solar batteries. The storm that descended on the planet blocked the access of the sun's rays. Perhaps there were other reasons, in the end no rover will not be able to work forever, but the lack of solar energy played a major role in the death of Opportunity. In turn, “Curiosity” works on the basis of RTG - a radioisotope thermoelectric generator (read: a compact nuclear reactor), so it doesn’t matter whether the Sun is in the sky or not.
Panoramic image made by roverOpportunity, where the solar panels of the device are visible. All scientific machine operations were stopped due to the fact that a global dust storm descended on the planet.
For all the time studying Mars, scientists have encounteredseveral global dust storms. The spacecraft Mariner-9, which reached our planetary neighbor in 1971, discovered that the planet was literally shrouded in dust. Since then, storms have been observed in 1977, 1982, 1994, 2001, 2007, and 2018. Moreover, in 1977, scientists witnessed two separate global storms at once, which further complicated the riddle of this phenomenon.
Scott Guzevich - a specialist in the field of scienceabout the atmosphere from NASA's Goddard Space Flight Center. It was under his leadership that the latest research on the study of Martian dust storms was carried out. In a press release published on the NASA website, Guzevich notes that scientists are still not sure what causes such powerful atmospheric phenomena, but the dust storm of 2018 gave the researchers some new clues. Very important clues.
These photos were taken by the HiRise camera,installed aboard the MRO orbiting spacecraft circling around Mars. The picture on the left shows the crater, as it was before the beginning of the Martian storm. The right shows the same crater, but during the dust storm
The powerful dust storms of Mars can help researchers figure out where water could have gone from the surface of the Red Planet.
Geronimo Villanueva from the same Space CenterNASA's Goddard flight, who built his career in exploring the waters of Mars, together with colleagues from the European Space Agency and the Russian Roskosmos, found out where the water that once was on Mars, or at least most of it, could go.
“Global dust storms can give us the right explanation,” says Villanueva, a hydrologist from the Goddard Space Flight Center at NASA.
Everything is quite simple. Particles during very large-scale storms, water particles could rise with the dust into the upper atmosphere and evaporate under the influence of solar radiation.
"If you raise the water high in the atmosphere, then it will be much easier to get rid of it," explains Villanueva
The global dust storms of Mars are raising high inthe atmosphere is not only dust particles, the researchers note. They also lift up water microparticles. Usually they were found at altitudes of about 20 kilometers, but Villanueva and his colleagues from the ExoMars project, thanks to the space orbiter Trace Gas Orbiter, found that water particles during global dust storms can rise up to 80 kilometers above the surface of Mars. At such a height, the atmosphere of the planet is very low. The radiation of the Sun easily splits H2O molecules, and the solar wind blows the received hydrogen and oxygen further into space.
On Earth, moisture has risen to the atmospherecondenses and falls back as rain. However, this is not possible on Mars. It is quite probable that Mars will thus very slowly exhaust all of its water reserves.
You can discuss the article in our Telegram-chat.