Mars is an inhospitable place, with freezing temperatures, barely any oxygen, and radiation that bombards its surface. But one of the trickiest environmental problems to deal with there is something rather unexpected and even mundane: dust. Dust covers the planet and is whipped up into massive dust storms which can wreak havoc on machines and, potentially, human explorers too.
Now, though, new research is helping us understand this strange dusty environment and paving the way for safer Mars missions in the future — like a crewed landing and possibly even a permanent settlement.
The problem of dust
Mars's surface is covered in fine particles of dust. With its smaller size than Earth, it has lower gravity – around one-third of the gravity here – and a thinner atmosphere, which is around one percent of the density of Earth's atmosphere. That means it is easy for winds to form and to pick up those dust particles, blowing them into a dust storm.
Something that is unusual about Mars is just how big these dust storms can become. Sometimes, they can grow from regional events to global ones, covering whole portions of the planet. And that is a big problem for missions there.
Some robotic missions like NASA's InSight lander use solar panels for power, and when dust storms blow in they cover these panels in a layer of dust, rendering them less effective and dooming the missions to eventual power failure. Dust also gets into mechanical parts and wears them down, as the Apollo astronauts found when visiting the moon and dealing with lunar dust.
Another issue is that dust storms make it harder for spacecraft to land on Mars. Dust can erode the heat shields which protect spacecraft as they descend through the atmosphere, and the storms change atmospheric densities which affect how parachutes work. Current robotic missions deal with these challenges by hedging their bets, using thicker protective materials, and being prepared for windy and dusty descents. But there's always risk in trying to land on Mars.
Understanding dust storms
To make landing and operating craft on Mars safer, we need to know more about how dust storms form, move, and grow. We're just starting to understand this, thanks to missions like the UAE's Hope orbiter which arrived at the red planet in 2021. Researchers recently released data from Hope's first year of observations, which included tracking a massive dust storm that rolled across the planet.
The dust storm was detected in December 2021, observed using Hope's camera and spectrometer, the Emirates eXploration Imager (EXI), and Emirates Mars InfraRed Spectrometer (EMIRS). The storm quickly grew to cover thousands of kilometers across, blowing across the planet and passing over the Jezero crater where NASA's Perseverance rover and Ingenuity helicopter are currently exploring. Ingenuity had to delay one of its flights and perform special maneuvers to shake off the dust left behind by the storm.
The dust storm continued rolling across Mars for the first half of January before blowing itself out and clearing by January 14. Dust storms are seasonal affairs and typically become more common during the southern spring. Each event observed is a chance to learn more about martian weather.
“We’re always on the lookout for the unusual, for events that challenge our models and current understandings of Mars as a planet,” Hessa Al Matroushi, Science Lead for the mission, tells Inverse. “We’re already seeing completely new measurements and visualizations of Mars’ atmosphere, in part because Hope’s unique orbit lets us get a much clearer and holistic picture of the planetary atmosphere and dynamics, but also because of the design and synergy of our instruments.”
How to track a Martian dust storm
Hope sits in a highly elliptical orbit, meaning that it is sometimes closer to the surface and sometimes further away, moving from an altitude of 20,000 kilometers to 43,000 kilometers (12,000 to 27,000 miles). That's far higher than other Mars orbiters, such as NASA's MAVEN or ESA's Mars Express. This high altitude lets Hope observe the planet on a large scale, which means it can track weather events as they happen.
This, Matroushi says, gives the Hope mission “opportunities to survey the full globe. No other spacecraft to Mars has been able to give that range of coverage. That basically means we’re able to track these storms in new ways, with new insight into their development, duration, and impact on the planetary atmosphere — and that’s incredibly exciting.”
Using its EXI camera, Hope views the planet at three different wavelengths — three in the visible light range and two in the ultraviolet — which, taken together, create what the team calls a “weather satellite view”. Along with its spectrometer, which can see details about the composition of the atmosphere like the amount of dust or water ice present, the mission builds up a picture of weather across the planet.
Getting a big-picture view while a dust storm develops can help us understand more about how and why some storms grow so big, EXI Instrument lead Mike Wolff tells Inverse.
“We are definitely still learning how storms evolve and grow,” he said. “One area of active investigation is the role played by the dust sources and sinks across the planet and their connections to both regional and planet-encircling events.”
The future of crewed missions
By understanding dust storms, we can help improve the survival of both robotic and eventual crewed missions to Mars. Although the threat of dust storms to people isn't quite as dramatic as it is shown in fiction — it's “more likely to be an issue with creating temporary problems with activities; not the life-and-death situation portrayed in The Martian,” Wolff says — there's still a need to predict dust to enable safer landings and better long-term operations of machines on the planet's surface.
And as is often the case with space missions, there's the potential that what we learn beyond Earth could be applied to better life here as well.
“Hope gives us new opportunities to look at the impact of lifting aerosols and dust, with new measurements of those dynamics that could — should — help us to understand Mars’ unique atmosphere,” Matroushi said. “Can we map that to lessons to learn for Earth? I am convinced there are lessons there to learn, we just need to delve deep enough to learn them.”