Global dust storms can become predictable, it is natural to simplify the life of future Martian pioneers. The new study was able to build a model indicating that the Red Planet will experience a similar event in the next few months. She also indicates that it is expected to start on October 29th or a few weeks from the date indicated.
Local dust storms are very common on Mars. They sometimes grow, merge and form a regional one, especially during the southern spring and summer, when the planet is closest to the Sun. Quite often, regional storms are the cause of the formation of a dusty fog that encircles the planet and does not allow you to see the surface from above.
But sometimes, regional ones are transformed into global ones; one of them, in 1971, was observed by the first spacecraft launched into the orbit of Mars, Mariner-9, as well as the Soviet stations Mars-2 and -3. Creating a kind of template by which it is possible to determine the beginning of global storms in a few years is still considered an unsolved problem.
The last storm on a planetary scale occurred in 2007. It was then that the flow of sunlight to the surface significantly decreased, which led to problems in the operation of two all-terrain vehicles - Spirit and Opportunity. Actually, this event was the first significant threat to all-terrain vehicles since landing.
Special measures had to be taken to ensure their survival for several weeks, in conditions with little sunlight. Both rovers worked for only a few minutes a day, and then only to provide heating for on-board equipment, and then turned off and did not communicate with the Earth at all during the next day.
Dust storms will create serious problems for the first colonists of the Red Planet. Although the force of the wind is not as strong there as portrayed in the movie The Martian, dust during storms will definitely affect the electronics as well as the availability of sunlight.
Since 1924, 9 global dust storms have been recorded on the Red Planet, of which the last five were discovered in the period 1977-2007. It is clear that their number is undoubtedly greater. The fact is that in some periods of time there were no research vehicles in the orbit of Mars in order to observe such a phenomenon at close range. It is extremely difficult to see them from Earth.
The study found a pattern in the onset of storms, if the orbital motion of Mars is accurately taken into account. It has been found that sometimes other celestial bodies influence its rotation around the Sun. If the influence increases, global storms usually occur during the first part of the storm season. None of them happened in years when influence was waning.
The present conditions on Mars are very similar to those when global storms have occurred in the past. Atmospheric observations in the coming months will check whether the forecast is correct.
During the exploration of Mars by the Soviet automatic stations "Mars-2", "Mars-3" and the American station "Mariner-9", a severe dust storm broke out on the planet. It started in September 1971.
On that day, Earth's observatories detected a white cloud band approximately 2,400 kilometers long and 400 kilometers wide. Then the band turned yellow and began to quickly, at a speed of about 100 kilometers per day, spread westward across the planet, covering it with a yellow haze. After 16 days, a thick veil enveloped the entire western hemisphere of Mars. By the end of October, nothing could be seen on the planet. The atmosphere began to clear up only in mid-December 1971.
Why are there such strong dust storms on Mars?
The first clouding of certain regions of Mars was noticed by the French astronomer O. Flougerget in 1796-1809. About one hundred and fifty years ago, scientists first suggested that the yellow clouds on the planet were composed of dust particles. Later it was found that these clouds appear where the surface of Mars heats up more than usual.
Yellow clouds almost every time cover the entire planet at a time when it is near perihelion - the point of its orbit closest to the Sun. At this time, in the southern hemisphere of Mars, where global storms occur, summer is just beginning. The connection between the heating of the planet and the appearance of an all-Martian dusty veil has been repeatedly noted by astronomers. They noticed her in different years. These are the years of the great oppositions of Mars, when it comes closest to the Earth and when we can best view it.
Further studies have shown that the rise of small amounts of dust into the atmosphere of Mars occurs almost always in the warm season at Martian noon and afternoon hours. This was confirmed by the analysis of tens of thousands of photographs taken under the program of the International Planetary Patrol.
So, large dust storms on Mars appear when the surface of the planet is overheated. Another necessary condition is the wind of a sufficiently high speed: about 50 meters per second. The vertical motions in the atmosphere and the degree of surface roughness are also important.
The beginning of the storm can be imagined as follows. First, particles with a size of about 200 microns rise. Heavier winds cannot yet lift off the surface, and lighter ones do not take off due to vortices. The wind speed increases - large and small particles rise. Large ones immediately fall to the surface and knock out smaller ones up. They, in turn, rise to great heights. The flow can weigh the particles, hold them in itself. The particle size is one or several microns.
Finally, the dust cloud has reached a large size, the concentration of dust in it is very high. A new stage begins: the cloud influences the flow that gave birth to and carries it. Flying particles streamline the movement of the wind, make it more stable and therefore faster. This paradoxical fact was established by Soviet scientists while studying dust storms in Kazakhstan. Terrestrial dust storms sometimes reach simply frantic force - the wind speed often exceeds 40 meters per second.
On Mars, temperature differences near the surface of the planet can reach 100 degrees Celsius. The temperature can also change dramatically with height - within literally a few meters. This creates instability in the atmosphere and contributes to an increase in wind speed with height. It is clear why dust storms occur during the warm season - the heating of the surface makes the Martian atmosphere the most unstable.
And finally, one more circumstance. When a planet is covered by a dusty cloud, much of the solar radiation is absorbed by the dust in the planet's atmosphere. Therefore, the atmosphere becomes warmer, and the surface of the planet - colder than usual. Because of this, strong eddies can occur under dusty clouds. They are becoming the new suppliers of dust to the cloud. This will stop only when the cloud becomes large enough and reduces the temperature contrasts in the atmosphere. Dust particles will begin to fall out.
What about our planet? Dust storms on Earth are among the most dangerous natural phenomena. To fight them, you need to know everything about them. That is why the study of dust storms in planetary science is so interesting and important.
It is known that dust storms rage on Mars, these storms are incredibly large-scale and can envelop the entire planet. In addition, the surface of Mars is littered with countless whirlwinds that rush across its plains and kick up dust, which is carried away into a "dust cycle" unique to the planet.
Taken from orbit, show that the main cause of erosion on Mars is the wind. Vast dune plains, intricate rock formations and skies shrouded in haze - such is this harsh windy world.
Science fiction writers quickly picked up on the idea of frequent storms that look daunting from afar. Gigantic walls of dust, against which the greatest terrestrial dust or sandstorms look like ridiculous dwarfs, sparkling spears of lightning that arose due to atmospheric friction, monstrous hurricanes that sweep away everything in their path, scattering astronauts and warping equipment.
Alas, the reality of Martian dust storms is somewhat more modest, a fact that NASA wants to convey to audiences eagerly awaiting Ridley Scott's new film, The Martian.
Based on Andy Weir's bestseller, the film is set in the near future during a manned mission to Mars. Due to a ferocious dust storm, the mission fails, the planetary base is damaged, and one of the astronauts, Mark Watney (played by Matt Damon), is lost after damage to the spacesuit and colleagues decide that he died in the terrible Martian winds.
But, like many other science fiction speculations about Mars, this scene misleads the viewer, since scientists have slightly different data on its atmospheric pressure.
While, of course, the dust storms of Mars are dangerous in their own way, they are extremely unlikely to throw anyone or damage anything. The strongest Martian wind blows at a speed of 60 miles per hour (less than 30 meters per second), half the speed of any terrestrial hurricane. In fact, however, the damage is caused not so much by the wind speed itself, but by atmospheric pressure, with which it is just tight on Mars. It is about one percent of the earth's, so if you decide to go kiting on the Red Planet, you will be in for quite a disappointment.
"The main difference between the atmospheres of Earth and Mars is that the pressure on the latter is much lower," says physicist William Farrell of the Goddard Space Flight Center in Greenbelt, Maryland, who analyzes Martian dust storms. “So, of course, the winds blow, but not that much.”
Although the most violent hurricane on Mars would be more like a breeze by Earth standards, Martian dust storms can still be a problem for future astronauts, especially if they are dependent on solar energy.
In The Martian, Watney cleans the solar panels every day to keep them free of dust. As the experience of solar-powered rovers, in particular NASA veteran Opportunity, which has been driving around Mars on solar power for a decade, has shown, this is a serious problem that seriously affects the amount of energy received. When the atmosphere is saturated with fine dust during storms, little or no sunlight reaches the surface.
"We are concerned about the power supply of the rovers, this is an important issue," says scientist Michael Smith, also from the Goddard Center. "The Spirit and Opportunity devices were delivered to the planet in 2004 and so far only got into one serious dust storm (in 2007), but then they had to actually stop functioning and go into life support mode for several weeks."
But fine dust causes inconvenience not only in connection with solar panels. Not only are its particles magnetized, they are also covered with sharp notches (since there are no other erosive processes on Mars to break them in) that can cause mechanical damage.
"If you've seen pictures of the Curiosity after the ride, remember that it looks like it's been dug out of a hole," Smith added. "Dust covers everything like a blanket, and clogs into all moving joints."
The dusty atmosphere of Mars will no doubt be a problem for ground vehicles, as well as the health of astronauts, if we ever send a long-term expedition there (in addition to increased levels of radiation and toxic substances in the Martian regolith and soil). In addition, the causes of planetary dust storms are still very poorly understood.
"Comparatively large dust storms happen on Mars every year, they take on continental dimensions and last for several weeks each," says Smith. “But every three Martian years (about five and a half Earth years), a normal storm grows to planetary sizes, we call such a “global dust storm”.”
“Maybe the storm needs time to gather its strength. Maybe there's some kind of cycle that she needs to go through and then get to the right place and start a new storm, or maybe it's just a matter of chance.
Humanity has been observing global dust storms on Mars since 1909, the last one happened in 2007, so Mars is just waiting for a new giant.
"We're in for a global storm and it's going to be really big this time, so it's going to be fun," he says. "I love dust storms."
With each subsequent storm on Mars, we learn more and more about the processes taking place there in order to better prepare for the first landing on this dusty, unfamiliar planet. But as for the fierce storms, you can be sure that no one but the Martian Watney will be blown away by the winds.
NASA has revealed truth and fiction about the dangers of dust storms on Mars, some of which may be visible from ground-based telescopes. This information was used in the creation of the new film "The Martian" directed by Ridley Scott. This was reported on the NASA website.
Dust tail (Photo: NASA / JPL-Caltech / University of Arizona)
The Martian, which will be released in October 2015, begins with Andy Weir's character (astronaut Mark Whitney) facing a massive dust storm. She rips off the transmitting antenna and destroys part of the camp. NASA does not deny that dust storms are one of the troublesome features of the Red Planet.
"Mars experiences moderate-to-large dust storms every year that cover areas the size of an Earth continent and last for weeks," said planetary scientist Michael Smith of NASA's Goddard Space Flight Center in Greenbelt, Maryland.
Meanwhile, on the Red Planet, as the scientist noted, much stronger storms are also observed. Global dust storms form from moderately large ones and manifest themselves on average once every three Martian years (this corresponds to about 5.5 Earth years).
However, as the scientist notes, it is unlikely that these dust storms can even disturb the hair of an astronaut on the Red Planet (if the latter decides to take off his spacesuit). In addition, even global dust storms are unlikely to be able to topple or destroy any equipment.
This is due to the fact that the speed of the strongest winds on Mars does not exceed 27 meters per second, which is more than half the speed of some hurricane winds on Earth. In addition, the density of the Martian atmosphere is a hundred times less than that of the earth.
Dust from a 2008 storm covered the Spirit panels (Photo: NASA/JPL-Caltech/Cornell)
"The main difference between Earth and Mars is that the atmospheric pressure on the Red Planet is much lower," said plasma physicist William Farrell. "So everything [particles in Mars' atmosphere] becomes wind, but not at the same intensity [compared to Earth]," he added.
However, dust storms on Mars are not entirely harmless. Individual small dust particles can carry an electrostatic charge and "stick" to surfaces, in particular, portholes and mechanical parts of scientific equipment.
The neutralization of electrostatic charges and the elimination of dust pollution is one of the main tasks that engineers solve when designing equipment for Mars exploration.
This same dust is a big problem for solar panels. Even small dust storms can bring enough particles onto solar panels to significantly reduce the amount of solar energy.
In the movie The Martian, astronaut Whitney cleans up dust pollution from solar panels on a daily basis. NASA also notes that global storms on Mars may also lead to some dimming of the Red Planet's atmosphere.
“We were really worried about the energy of the rovers. The Spirit and Opportunity rovers, which landed on Mars in 2004, only experienced a global storm once (in 2007) and basically shut down for a few weeks and went into survival mode,” Smith said.
Most often, global dust storms on Mars occur in the summer in the southern hemisphere of the planet. As on Earth, the seasons on the Red Planet are determined by its inclination to the plane of the orbit. However, the orbit of Mars is more elongated than that of the Earth, which means that during the Martian year one side of the planet is heated more than the other.
For more than a century now, science fiction writers from all over the world have been trying to imagine what life would be like for astronauts on Mars. But as humanity becomes more and more more and more aware of Martian conditions, science fiction writers' descriptions of life on Mars are becoming increasingly more realistic. More recently, The Martian is based on Andy Weir's sci-fi novel. The protagonist of The Martian, due to unforeseen circumstances, remains alone on the red planet and begins the struggle for survival. And at the beginning of the 20th century, the American author Edgar Rice Burroughs was already dreaming of traveling to Mars. In fairness, it’s worth saying that the red planet captured people so much that even the famous theologian and author of fantasy stories, Clive Staples Lewis, published a series of stories about it. It was he who created the cycle "The Chronicles of Narnia".
An artist's impression of a dust storm on Mars approaching a research station. Such phenomena on the red planet may well be accompanied by discharges of atmospheric electricity. Source: NASA
The Martian opens with a huge sandstorm that damages the transmitting antenna and some of the equipment, causing the fictional character Mark Watney to remain on Mars while the other mission members leave, presuming he is dead. This development looks very plausible, since Mars is famous for its very active sandstorms, which sometimes become so large that they can be observed in telescopes on Earth.
“Each year, moderately large sandstorms occur on Mars, which cover areas the size of the Earth's continent and last for weeks after their formation. But about every three Martian years (5.5 Earth years), ordinary hurricanes turn into giant storms that can envelop the entire planet,” Michael Smith, planetary scientist at NASA Space Flight Center.
Scientists consider it unlikely that even planetary sandstorms on Mars will be able to lead to dire consequences. Even the strongest winds that are blowing at this time will not be able to destroy or even topple the specially deployed mechanical equipment. The winds in the strongest Martian hurricanes reach speeds of about one hundred kilometers per hour, more than half the speed of some hurricanes on Earth. That is why it is not worth focusing only on wind speed. Atmospheric density Mars makes up about one percent platmosphere Earth. This means that in order to fly a terrestrial kite on the red planet, the wind must blow much stronger.
“The main difference between Earth and Mars is that the atmospheric pressure on Mars is much lower. Thus, things and objects can be carried away from its surface, but not with the same force as on Earth,” William Farrell, plasma physicist.
Problems of solar energy
But be that as it may, the sandstorms of Mars are not completely harmless. Individual dust particles on the red planet are very small and slightly electrostatic, thus being able to "stick" to various surfaces.
“If you've ever paid attention, you can see in the pictures of the Curiosity rover that after each trip it gets very dirty. Dust covers almost everything. It even penetrates mechanisms and devices, ”- Michael Smite.
This ability of dust to penetrate anywhere and everywhere is a major problem for engineers designing equipment for Martian rovers. This is especially a big problem for solar panels. Even if the craft is caught in a very small dust storm or swirl, only a few meters in size, the wind can carry enough dust to cover the photovoltaic converters and significantly reduce the usable surface that can convert solar energy into electrical energy. If we turn to the same "Martian", then Mark Watney spends a certain amount of time every day to clean the solar panels to ensure their maximum performance.
This picture of itself was taken by the Opportunity rover three weeks before its 10th anniversary on Mars. The Pancam panoramic camera surveyed the rover between January 3rd and 6th, 2014. Pay attention to how dusty the solar panels are. Source: NASA/JPL-Caltech/Cornell Univ./Arizona State Univ.
Global hurricanes can also create a secondary problem that cannot be solved by simply blowing dust off the surface. So much dust can be permanently present in the atmosphere that some part of the sunlight will be blocked, and, consequently, the efficiency of solar panels will decrease. In the book, when an astronaut first encounters a large sandstorm, he immediately notices a slight decrease in the efficiency of his batteries, caused by a slight dimming of the atmosphere. This is a pretty accurate description of what explorers might encounter during actual Martian expeditions.
“Currently, we are very concerned about the power consumption of our rovers. The Spirit and Opportunity rovers landed in 2004, so they have only survived one global hurricane so far in 2007, which forced them to shut down and go on standby for weeks,” continues Michael Smite.
dust bustle
As mentioned, global sandstorms kick up enough dust into the air to completely cover the planet and obscure the sun. but in this way the hurricane itself also becomes doomed to extinction. The fact is that the main mechanism that sets in motion all these hurricanes is the high temperature of sunlight, which reaches exactly the surface of the planet. As the light hits the ground, it heats up the air close to its surface, leaving the upper layers cooler. As well as on Earth during thunderstorms, warm and cold air, mixing, become unstable, warm layers begin to rise, taking away dust particles with them due to instability. It is from such small swirls that all those strange dust “ghosts” seen in some images of Mars are formed. Then moderate-sized storms form, then - the size of a continent. Sometimes such large hurricanes can combine into one global vortex, which just covers the entire planet with dust.
Researchers and planetary scientists have determined quite accurately that large hurricanes usually occur during the summer in the southern hemisphere of Mars. It is known that on the red planet, as well as on Earth, there is a change of seasons, which is caused by the tilt of the planet's axis of rotation. But due to the fact that the orbit of Mars has a greater eccentricity than the orbit of the Earth, the red planet moves in a more elliptical orbit. The minimum approach to the Sun just coincides with the summer period in the southern hemisphere, and, therefore, the temperature values are the largest precisely then. Once a hurricane begins, it does not subside for weeks and even months. But scientists are still unsure what exactly causes such large gaps between hurricanes.
A dust vortex captured on Mars by the HiRISE camera of the Mars Reconnaissance Orbiter. This scene was captured during daytime in late Martian spring. The frame covers an area measuring 644 meters. Judging by the shadow that the vortex casts on the surface, it was possible to establish that it can reach 800 meters in height, and its diameter is about 30 meters.
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