Otherworldly weather forecasts could help future Mars explorers reach this vital resource

Technology 02:02 PM - 2021-08-31

The weather on Earth can be strange, but it may be nothing compared to global dust storms or nighttime snowfall on Mars that scientists are just beginning to understand.

Before we send humans to other destinations across the solar system, the ability to create accurate weather forecasts will be necessary, according to new research. And mapping Mars could help astronauts determine where to find critical resources, like melting ice.

Luckily, there are some similarities between Earth and Mars and even Saturn's moon, Titan, that allow scientists to lay the groundwork for forecasting weather on other planets.

"I believe the first accurate forecasts of perhaps a few Mars days may be only a decade away," said lead study author J. Michael Battalio, a postdoctoral researcher in Earth and planetary sciences in Yale University's Faculty of Arts and Sciences, in a statement.

"It is just a matter of combining better observational datasets with sufficiently refined numerical models," Battalio said. "But until then, we can rely upon connections between the climate and weather to help anticipate dust storms."

The researchers examined an Earth phenomenon known as an annular mode -- which is related to the planet's jet stream -- and tried to find it in weather patterns on Mars and Titan.

Annular modes are variabilities in Earth's atmospheric flow, unrelated to seasonal changes, that can impact the jet stream, cloud formation and precipitation across the globe. These modes also explain some of the lack of consistency in wind eddies, or the air circulations in New England's blizzards and severe Midwest storms.

Dust storms regularly occur in the Martian southern hemisphere, which reminded Battalio of eddies on Earth.

Battalio analyzed 15 years of atmospheric observations from Mars and discovered that much like Earth, the red planet has annular modes. Juan Lora, Battalio's lab supervisor and an assistant professor of Earth and planetary sciences at Yale, also developed a global climate model for Titan to search for annular modes on Saturn's largest moon.

During their research, the team discovered annular modes not only occur on Mars and Titan, but they are even more influential on these other planets than they are on Earth. Annular modes account for half of the wind variability on Mars and at least two-thirds of it on Titan.

The study published Monday in the journal Nature Astronomy.

"Methane clouds and surface changes caused by methane rain on Titan have been observed before," said Lora, a coauthor on the study, in a statement. "And now it seems these events are connected to shifts of Titan's strong jet stream, influenced by its annular modes."

This finding suggests that scientists could discover annular modes on other planets.

"The fact that we have found annular modes on worlds as different from Earth as Mars and Titan also means they may be ubiquitous in planetary atmospheres, from Venus, to the gas giants or exoplanets," Battalio said.
Understanding annular modes on Mars could reveal more information about the predictability of wind-driven storms on Mars, like small spin-up dust devils that last for a day or global dust storms that engulf the planet every few years. Like on Earth, the annular modes on Mars occur regularly and affect the eddies that drive dust storms.

"Understanding and predicting these events is vital for the safety of missions, particularly those that rely on solar power, but also for all missions as they land on the surface," Battalio said. "During larger regional events, the dust can become so thick at times as to make day seem as dark as the middle of the night. Even without a large, dramatic event, regional storms are a periodic feature."

Dust storms on Mars have already ended one robotic mission. The Opportunity rover, which landed on Mars in 2004, was meant to explore the red planet for 90 days. It endured for more than a decade and the mission's team regularly sent commands to the rover to shut down during dust storms. But a devastating global dust storm ended Opportunity's mission in 2019.

"A global event is what finally ended the Opportunity rover, but the slow accumulation of dust is currently endangering the survival of the InSight mission," Battalio said.

Apart from stunning photos showing thick ice at the Martian poles, it's hard to picture snow falling on the red planet. But in 2008, NASA's Phoenix Lander detected snowfall on Mars. Snowfall on the red planet is driven by the poles and likely occurs at night.

Using data from the Phoenix Lander, as well as the Mars Reconnaissance Orbiter, Arizona State University doctoral student Aditya Khuller and his colleagues determined that snow and ice looks a little different on Mars.

When snow forms on Mars, dust is one of the ingredients, causing it to look more like dirty snow we see on Earth. And once this snow falls, it's also covered by Martian dust. These combined factors cause Martian snow and ice to not only be dusty, but much darker than what fresh snow looks like on Earth. This research published August 18 in American Geophysical Union's Journal of Geophysical Research: Planets.

It poses an intriguing idea as well. Dust could be warming this snow and ice, which could cause it to melt into the Martian subsurface -- a place where microbial life could potentially exist, protected from the harsh, cold, radiated surface.

"There is a chance that this dusty and dark ice might melt a few centimeters down," Khuller said. "And any subsurface liquid water produced from melting will be protected from evaporating in Mars' wispy atmosphere by the overlying blanket of ice."

Khuller's research into the potential melting of this ice is ongoing, and it could reveal more about the climate history of Mars. The more scientists learn about the mysterious past of Mars' climate, the more they realize the planet likely experienced multiple ice ages.

His previous research has detected dusty water ice at the mid-latitudes of Mars, which could have formed gullies and ravines in the area close to the equator.

"If the snow or ice is truly melting, then they could be carving these channels," Khuller said. "Additionally, if there's liquid water being produced in the summer, a few centimeters down, then that would be if you were a microbe on Mars, that would be a good spot to go and get some water."

Understanding where liquid water deposits might be on Mars, which could occur if this ice melts during the Martian summer, might provide water that future explorers could access.



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