Lee waves: Lee waves are a special type of cloud created by the wind encountering obstacles and build up on the ‘leeward‘ or downwind side. The geometries of the lee waves depend on the shape of the obstacles. Credit: ESA/DLR/FU Berlin.
Mars has always held a special place in our hearts, likely from hints over the decades of perhaps finding signs of life, albeit fossilised and primitive. It’s been the subject of study from telescopes and space missions alike, most notably ESA’s Mars Express which has been observing the red planet for 20 years. Over the two decades of observation it has studied an amazing variety of atmospheric phenomenon which have now been catalogued in a new ‘Cloud Atlas.’ Many will be familiar to sky watchers on Earth but some are very different.
NASA's Mars Helicopters: Present, Future, and Proposed: A family portrait of Mars helicopters - Ingenuity, Sample Recovery Helicopter, and a future Mars Science Helicopter concept. Credits: NASA/JPL-Caltech.
There’s no way to sugarcoat it: Mars has a “dust problem.” The surface of the Red Planet is covered in particulate matter consisting of tiny bits of silica and oxidized minerals. During a Martian summer in the southern hemisphere, the planet experiences dust storms that can grow to encompass the entire planet. At other times of the year, dust devils and dusty skies are a persistent problem. This hazard has claimed robotic explorers that rely on solar panels to charge their batteries, like NASA’s Opportunityrover and the InSightlander, which ended their missions in 2018 and 2022, respectively.
Martian dust has also been a persistent challenge for the Ingenuity helicopter, the rotorcraft that has been exploring Mars alongside NASA’s Perseverance rover since February 2021. Luckily, the way it has kicked up dust has provided vital data that could prove invaluable for rotorcraft sent to explore other extraterrestrial environments in the future. Using this data, a team of researchers (with support from NASA) has completed the first real-world study of Martian dust dynamics, which will support missions to Mars and Titan (Saturn’s largest moon) in this and the next decade.
Dust is an everyday feature on Mars and wreaks havoc on various pieces of equipment humans decide to send to it, such as Insight’s continual loss of power or the losses of Opportunity and Spirit. But we’ve never really understood what causes the dust to get up into the air in the first place. That equipment that is so affected by it usually isn’t set up to monitor it, or if it is, it has been sent to a place where there isn’t much dust, to begin with. Now, that has changed with new readings from Perseverance in Jerezo crater, and the answer shouldn’t be much of a surprise – dust devils seem to cause some of the dust in the atmosphere on Mars. But strong winds contribute a significant amount too.
NASA’s Perseverance Mars rover took a selfie with the Ingenuity helicopter, seen here about 13 feet (3.9 meters) from the rover. This image was taken by the WASTON camera on the rover’s robotic arm on April 6, 2021, the 46th Martian day, or sol, of the mission. Credits: NASA/JPL-Caltech/MSSS.
The first flight of 2022 for the Ingenuity Helicopter has been delayed due to a regional dust storm on Mars. Mission planners had originally targeted January 5 for the tiny helicopter’s 19th flight, but they needed to push back the flight when orbital images and weather instruments on the Perseverance rover indicated a worsening weather situation.
Weather conditions have now improved, however, and the Ingenuity team anticipates the next flight will take place on Sunday, January 23.
Two snapshots, about two weeks apart, of a 3D simulation of the 2018 Global Dust Storm performed with the NASA Ames Mars Global Climate Model. The storm began as a regional storm in Acidalia then moved eastward, triggering more dust lifting along the way (in Arabia, Sabaea, Hellas etc.). As the storm grew larger and became global, intense dust lifting events occurred in the Tharsis region, injecting dust at high altitudes. Credit: Tanguy Bertrand / Alex Kling / NASA Ames Research Center
In 2018, Mars experienced one of its global dust storms, a phenomenon seen nowhere else. As science would have it, there were no fewer than six spacecraft in orbit around Mars at the time, and two surface rovers. This was an unprecedented opportunity to watch and study the storm.
Our eyes can’t see them, but Martian auroras are there, and more commonplace than we once thought. The Martian auroras were first discovered in 2016 by NASA’s MAVEN spacecraft. Now some new results are expanding our knowledge of these unusual auroras.
It’s easy to take for granted the detailed, almost real-time knowledge of Mars that we have at our fingertips. After all, in the not-too-distant past, Mars was largely mysterious. All we had were ground-based images of the planet. Now? Now we have daily weather reports and images of dust storms.
NASA's Opportunity rover appears as a blip in the center of this square. This image taken by HiRISE, a high-resolution camera onboard NASA's Mars Reconnaissance Orbiter, shows the dust storm over Perseverance Valley has substantially cleared. Image Credit: NASA/JPL-Caltech/Univ. of Arizona
A new image produced by the High-Resolution Imaging Science Experiment (HiRISE) aboard NASA’s Mars Reconnaissance Orbiter (MRO) has located the Opportunity rover on Mars. As expected, the rover was spotted on the slopes of the Perseverance Valley, where it went into hibernation mode about 100 days ago when the planet-covering dust storm darkened skies above the region.
Artist's impression of the Opportunity Rover, part of NASA's Mars Exploration Program. NASA/JPL-Caltech
Martian dust storms are a pretty common occurrence, and generally happen whenever the southern hemisphere is experiencing summer. Though they can begin quite suddenly, these storms typically stay contained to a local area and last only about a few weeks. However, on occasion, Martian dust storms can grow to become global phenomena, covering the entire planet.
One such storm began back in May, starting in the Arabia Terra region and then spreading to become a planet-wide dust storm within a matter of weeks. This storm caused the skies over the Perseverance Valley, where the Opportunity rover is stationed, to become darkened, forcing the rover into hibernation mode. And while no word has been heard from the rover, NASA recently indicated that the dust storm will dissipate in a matter of weeks.
The update was posted by NASA’s Mars Exploration Program, which oversees operations for the Opportunity and Curiosity rovers, as well as NASA’s three Mars orbiters (Mars Odyssey, MRO, and MAVEN) and the Insight lander (which will land on Mars in 109 days). According to NASA, the storm is beginning to end, though it may be weeks or months before the skies are clear enough for Opportunity to exit its hibernation mode.
This global map of Mars shows a growing dust storm as of June 6, 2018. The map was produced by the Mars Color Imager (MARCI) camera on NASA’s Mars Reconnaissance Orbiter spacecraft. The blue dot indicates the approximate location of Opportunity. Image Credit: NASA/JPL-Caltech/MSSS
As noted, dust storms occur on Mars when the southern hemisphere experiences summer, which coincides with the planet being closer to the Sun in its elliptical orbit. Due to increased temperatures, dust particles are lifted higher into the atmosphere, creating more wind. The resulting wind kicks up yet more dust, creating a feedback loop that NASA scientists are still trying to understand.
Since the southern polar region is pointed towards the Sun in the summer, carbon dioxide frozen in the polar cap evaporates. This has the effect of thickening the atmosphere and increasing the surface pressure, which enhances the process by helping suspend dust particles in the air. In some cases, the dust clouds can reach up to 60 km (40 mi) or more in elevation.
Planet-wide dust storms are a relatively rare occurrence on Mars, taking place every three to four Martian years (the equivalent of approximately 6 to 8 Earth years). Such storms have been viewed many times in the past by missions like Mariner 9 (1971), Viking I (1971) and the Mars Global Surveyor (2001). In 2007, a similar storm took place that darkened the skies over where Opportunity was stationed – which led to two weeks of minimal operations and no communications.
While smaller and less intense the storm that took place back in 2007, the current storm intensified to the point where it led to a level of atmospheric opacity that is much worse than the 2007 storm. In effect, the amount of dust in the atmosphere created a state of perpetual night over the rover’s location in Perseverance Valley, which forced the rover’s science team to suspend operations.
Simulated views of a darkening Martian sky blotting out the Sun from NASA’s Opportunity rover’s point of view, with the right side simulating Opportunity’s view in the global dust storm as of June 2018. Credit: NASA/JPL-Caltech/TAMU
This is due to the fact that Opportunity – unlike the Curiosity rover, which runs on nuclear-powered battery – relies on solar panels to keep its batteries charged. But beyond suspending operations, the prolonged dust storm also means that the rover might not be to keep its energy-intensive survival heaters running – which protect its batteries from the extreme cold of Mars’ atmosphere.
Luckily, NASA scientists who have been observing the global event indicated that, as of last Monday (July 23rd), more dust was falling out of the planet’s thin air than was being raised into it. This means that the global weather event has reached its decay phase, where dust-raising events either become confined to smaller areas or stop altogether.
Using its Mars Color Imager (MARCI) and Mars Climate Sounder (MCS), NASA’s Mars Reconnaissance Orbiter (MRO) also noted surface features were beginning to reappear and that temperatures in the middle atmosphere were no longer rising – which indicates less solar heating by dust. The Curiosity rover also noted a decline in dust above its position in the Gale Crater on the other side of the planet.
This is certainly good new for the Opportunity rover, though scientists expect that it will still be a few weeks or months before its solar panels can draw power again and communications can be reestablished. The last time communications took place with the rover was on June 10th, but if there’s one thing the Opportunity rover is known for, it’s endurance!
When the rover first landed on Mars on January 25th, 2004, its mission was only expected to last ninety Martian days (sols), which is the equivalent of about 92.5 Earth days. However, as of the writing of this article, the rover has endured for 14 years and 195 days, effectively exceeding its operational lifespan 55 times over. So if any rover can survive this enduring dust storm, its Opportunity!
In the meantime, multiple NASA missions are actively monitoring the storm in support of Opportunity and to learn more about the mechanics of Martian storms. By learning more about what causes these storms, and how smaller ones can merge to form global events, future robotic missions, crewed missions and (quite possibly) Martian colonists will be better prepared to deal with them.
True color image of a storm front located near Utopia Planitia, near the northern polar ice cap of Mars. Credit: Credits: ESA/DLR/FU Berlin
The weather patterns on Mars are rather fascinating, owing to their particular similarities and differences with those of Earth. For one, the Red Planet experiences dust storms that are not dissimilar to storms that happen regularly here on Earth. Due to the lower atmospheric pressure, these storms are much less powerful than hurricanes on Earth, but can grow so large that they cover half the planet.
Recently, the ESA’s Mars Express orbiter captured images of the towering cloud front of a dust storm located close to Mars’ northern polar region. This storm, which began in April 2018, took place in the region known as Utopia Planitia, close to the ice cap at the Martian North Pole. It is one of several that have been observed on Mars in recent months, one which is the most severe to take place in years.
The images (shown above and below) were created using data acquired by the Mars Express‘ High Resolution Stereo Camera (HRSC). The camera system is operated by the German Aerospace Center (DLR), and managed to capture images of this storm front – which would prove to be the harbinger of the Martian storm season – on April 3rd, 2018, during its 18,039th orbit of Mars.
Anaglyph 3D image of the dust storm front forming above the subpolar plains in northern Mars. Credit: Credits: ESA/DLR/FU Berlin
This storm was one of several small-scale dust storms that have been observered in recent months on Mars. A much larger storm emerged further southwest in the Arabia Terra region, which began in May of 2018 and developed into a planet-wide dust storm within several weeks.
Dust storms occur on Mars when the southern hemisphere experiences summer, which coincides with the planet being closer to the Sun in its elliptical orbit. Due to increased temperatures, dust particles are lifted higher into the atmosphere, creating more wind. The resulting wind kicks up yet more dust, creating a feedback loop that NASA scientists are still trying to understand.
Since the southern polar region is pointed towards the Sun in the summer, carbon dioxide frozen in the polar cap evaporates. This has the effect of thickening the atmosphere and increases surface pressure, which enhances the storms by helping to suspend dust particles in the air. Though they are common and can begin suddenly, Martian dust storms typically stay localized and last only a few weeks.
While local and regional dust storms are frequent, only a few of them develop into global phenomena. These storms only occur every three to four Martian years (the equivalent of approximately 6 to 8 Earth years) and can persist for several months. Such storms have been viewed many times in the past by missions like Mariner 9 (1971), Viking I (1971) and the Mars Global Surveyor (2001).
This global map of Mars shows a growing dust storm as of June 6, 2018. The map was produced by the Mars Color Imager (MARCI) camera on NASA’s Mars Reconnaissance Orbiter spacecraft. The blue dot indicates the approximate location of Opportunity. Image Credit: NASA/JPL-Caltech/MSSS
In 2007, a large storm covered the planet and darkened the skies over where the Opportunity rover was stationed – which led to two weeks of minimal operations and no communications. The most recent storm, which began back in May, has been less intense, but managed to create a state of perpetual night over Opportunity’s location in Perseverance Valley.
As a result, the Opportunity team placed the rover into hibernation mode and shut down communications in June 2018. Meanwhile, NASA’s Curiosity rover continues to explore the surface of Mars, thanks to its radioisotope thermoelectric generator (RTG), which does not rely on solar panels. By autumn, scientists expect the dust storm will weaken significantly, and are confident Opportunity will survive.
Understanding how global storms form and evolve on Mars will be critical for future solar-powered missions. It will also come in handy when crewed missions are conducted to the planet, not to mention space tourism and colonization!
