Dust storms are a regular feature on Mars, often building into planet-engulfing clouds that last months or years. MAVEN and Odyssey use thermal cameras to monitor these duststorms with precision.
At first, a spring breeze blew rusty dust through NASA’s Opportunity rover at Perseverance Valley. But then it quickly expanded and blocked out the sun completely, prompting NASA’s Opportunity rover to switch into survival mode.
Causes
NASA currently has six spacecraft orbiting Mars from orbit and two still exploring its surface, giving scientists and robots plenty of eyes on it. Therefore, when a planet-wide dust storm appeared recently, scientists and robotic rovers had plenty of data for analysis and sharing with the rest of humanity.
Like their Earth counterparts, dust storms on Mars are caused by solar heating that warms the atmosphere and makes it churn, lifting tiny particles into the air and giving rise to dust storms. But unlike Earth, there’s no precipitation available to wash away this dust as quickly – giving its characteristic swirly look.
Solar heating fuels the winds on Mars that cause dust squalls. But their course can be more unpredictable than on Earth; scientists don’t fully understand why, though some suspect it could have something to do with Mars’ rotation and tilt; each spin of Mars provides it with extra or reduced energy, giving rise to regional dust squalls which often become full-scale storms.
One of the best places to study these weather phenomena is from Mars Global Surveyor’s orbiting spacecraft, which took daily all-planet pictures between 1996 and 2006 and provided scientists with an unparalleled view of dust storms as they unfold across Martian landscapes while also taking into account other Martian weather elements and surface topographies.
Scientists have noted that dust storms often begin in the Hellas Basin, an enormous impact crater on Earth’s western edge. This is due to heat differentials within this vast impact crater being up to 10 degrees warmer than surrounding air temperature; this heat difference provides energy for wind action to pick up dust particles.
Another factor is our planet’s elliptical orbit, which brings it closer to the Sun during southern spring and summer and further away during its winter. This causes more solar radiation to reach us each time around but our ability to reradiate can’t keep up with that increase resulting in net energy losses that scientists believe could trigger global duststorms as seen recently.
Locations
Researchers use Mars orbiters to closely track its weather. They have tracked dust storms as they form, bloom and dissipate across its orange surface. One instrument, such as NASA’s Thermal Emission Spectrometer on NASA’s Mars Global Surveyor, measures temperature changes in the atmosphere to measure dust distribution and act upon it; additionally it photographs all areas of Martian surface every day providing researchers with unparalleled views into how storms start and move across this hostile world.
Once again, let us celebrate together this momentous event by gathering at the foot of Mount Fuji for a photo op and some light chit chat! Dr Agustin Sanchez-Levaga of the Universidad del Pais Vasco/EHU of Spain led a team in studying images captured by both Mars Express’ Visual Monitoring Camera and Mars Reconnaissance Orbiter High Resolution Stereo Camera that show images of storm growth as it expanded from regional to planet-encircling dimensions. Scientists utilized the Ensemble Mars Atmospheric Reanalysis System, or EMARS, which provides weather updates using flow-dependent covariances calculated from 16 ensemble members. Each member has different dust opacity and water ice radiative forcing parameters, but all begin from the same state produced by a Mars General Circulation Model. By adding observations into the model (through data assimilation), scientists can explore how changes to atmospheric states impact movement of dust or other fields not directly visible to human eyes.
Dust storms on Mars can last for months and damage spacecraft, preventing them from communicating with Earth or providing enough energy for functioning rovers on its surface. They may even prevent solar panels from producing enough power for them to operate efficiently.
Scientists postulate that global dust storms could spread throughout the planet due to Mar’s closer approach to the Sun during summertime. Such storms could be fed by its orbit around the gravitational center of our solar system and its wobble effect which causes solar wind and mesosphere clouds.
Scientists are investigating how these dust storms alter Mars and their impact on rover operations to better prepare for future missions. Both Viking and Opportunity survived two large dust storms after landing on Mars in 1976; both stopped performing science during this year’s month-long global storm to conserve power and save power for longer. Scientists expect Curiosity rover, with its nuclear power, will remain functional through any future long-lasting storms.
Effects
NASA’s two rovers temporarily suspended science activities and communicated with Earth to conserve power during this early 2022 duststorm; however, orbiters that monitor Mars from above were still capable of gathering information regarding its effects and aftermath.
Mars’ atmosphere is an ever-evolving mix of gases–including carbon dioxide and water vapor–that are held together by an atmosphere that’s less dense than Earth. At its surface, Mars is heated by sunlight and loses mass through radiation; this causes its air mass to shift around, rising and moving around with it; drawing moisture up from below as it condenses on carbon dioxide molecules for formation into clouds that will eventually rain or snow from above.
These processes contribute to seasonal weather on Mars, most notably its southern hemisphere during summer. Mars comes closer to its Sun at this time, absorbing more energy and warming faster. Increased heating creates conditions which drive winds which in turn stir up dust clouds.
Mars has been subject to billions of years of erosion, creating a surface covered in dust and grit for billions of years – enough so to cause serious damage to moving parts on equipment there. Furthermore, these particles have an electrostatic charge which causes them to be drawn towards surfaces and adhere like foam packing peanuts.
Scientists cannot anticipate when or if a planet-wide dust storm will occur on Mars; however, they are certain that one is coming at some point in time. Conditions that make such events likely already exist: the low gravity and thin atmosphere allow dust particles to jump higher than on Earth when hitting rocks; colliding with other rocks–resulting in collisions which chip away bits of rock along their paths.
Observations
As Mars continues its stormy journey, scientists are gaining unprecedented insight into how its dust storms work. By making use of daily images captured by NASA’s Mars Orbiter Camera and knowing that global storms form when there is an imbalance between how much solar energy Mars absorbs and what it re-radiates back out into space, scientists are gaining unprecedented detail into when and where these events may take place.
Clouds compose much of our atmosphere, formed as the surface is heated by sunlight and air is forced upward. They often form regular spacing of smaller clouds resembling pebbles or grains of sand that scientists interpret as evidence for closed-cell convection; where cooler air sinks down beneath hot rising air to allow continued cloud formation.
These clouds resemble mesospheric (or noctilucent) clouds that form above Earth and last up to six months, appearing faint against a dark sky backdrop and reflecting sunlight rather than absorbing it.
Dust storms on Mars have not reached global scale yet, yet remain widespread enough to cover much of its surface. Opportunity remains inactive, unable to charge its batteries or communicate with Earth and will remain so until this storm has dissipated; its expected to happen when Red Planet passes its spring equinox in February 2022.
Owing to its limited extent, the current storm may provide some respite from dust. Because its winds are blowing across from the north instead of from the south, perhaps explaining why its coverage wasn’t global and blanketed all of Mars’ surface. Scientists will continue to track this event and others like it as they try to predict when these events may recur.