The first observational research showing that gravity waves triggered by major dust storms could cause the escape of atmospheric gases from Mars into outer space does not bode well for human settlement, according to scientists working with NASA.
Their research letter, published this month in Geophysical Letters, stems from an analysis of carbon dioxide density that was conducted onboard NASA spacecraft. In the first-ever estimates of how gravity waves might influence atmospheric loss, it suggests that severe and lengthy dust storms, and the resulting escape of planetary gases, pose added complications to the prospect of humans settling on Mars.
Erdal Yiğit, the study’s lead researcher and an associate professor of physics at George Mason University, told The Academic Times that this atmospheric loss “could have had a great impact on climate evolution on Mars over very large time scales ... millions of years, and it could have been responsible for the current dry and cold situation.”
That, the study suggests, is because with each passing Martian year, Mars is losing carbon dioxide that could otherwise help to warm the extremely cold planet, which until it lost its magnetic field and most of its atmosphere about 4 billion years ago is generally thought to have been warm and wet.
The findings come as NASA’s Mars 2020 Perseverance rover nears landing, and NASA looks to engage the public with a touchdown scheduled for 3:55 p.m. EST on Thursday. Trudy Kortes, director of technology demonstrations at NASA, said at a media briefing Tuesday that the development of the technology leading up to Mars 2020 and the demonstrations that will take place on the rover upon landing "are so critical to continue to make these advancements, and required to send more sophisticated robotic explorers, as well as humans, to places in the solar system we’ve never been able to send them before."
The recently published research formed part of the Mars Atmosphere and Volatile EvolutioN, or MAVEN, mission of NASA's Mars Scout program, which aims to understand whether there is or can be life on the Red Planet.
Dust storms, particularly those circulating entire planets, were at the heart of the research. Yiğit’s team studied how large-scale, long-lasting dust storms can affect the climate and weather on Mars and ultimately found that they modulate gravity wave activity. Once that was established, it led to the observation of a second connection, this time between the influence of such gravity waves and atmospheric escape.
"There is more gravity wave activity in the atmosphere during storms, and these waves can promulgate all the way from the bottom of the atmosphere on Mars to the top of the atmosphere, meaning up to 200 kilometers and more, which ultimately affects how much atmosphere is lost into space," Yiğit said.
Researchers observed not only how planet-circulating dust storms cause atmospheric loss, with real-time satellite measurements, but also how they can help to explain the orange-red tint of Mars.
“In the images, you can see that if there’s a dust storm, the planet is completely orange, very orange,” Yiğit says. “If there's no dust storm, you'll see the surface [of Mars] from the space telescopes.”
And the storms can cover huge surface areas, Yiğit said: If they took place on Earth, the spaces from North America to Asia and from Antarctica to the North Pole would be completely covered in dust. They can also be lengthy, lasting between two and four months, and are largely unpredictable. The last one, spanning several months, happened in 2018.
For programs like NASA’s, the findings bring new implications for exploring the potential for life on Mars. Amid conflicting information, assessing that potential is already complicated, Yiğit said, in part because of the open and essential question of whether there is water on Mars.
“The Mars atmosphere cannot sustain liquid water in the scales and amounts that we’re familiar with on Earth,” Yiğit explained. “If the planet is so dry and so cold, then it’s very difficult for life to form, and if it’s formed, it’s not going to last long.”
The issue of water aside, merely settling on Mars “is going to be very challenging” because of the dust storms, Yiğit said.
“There’s no visibility inside the dust storm. Just being on the surface of Mars, for three or four months of dust storm, humanity would be stuck in a capsule, or dome,” unable to venture out for research, he said.
New questions have also emerged regarding details surrounding the physical process described in the research, from how the phenomenon of atmospheric escape happens to what this could mean for the Martian thermosphere over time.
“This paper opened a box of worms,” Yiğit said. “I'm confident there will be new discoveries about this.”
Yiğit plans to next look at the physics behind atmospheric escape on Mars in detail. He explained that additional research can use the evidence that dust storms, gravity waves and atmospheric escape are connected as a benchmark to further explore the idea of humans residing on Mars.
"If we would like to imagine Mars as a second home, we would have to deal with this problem [of atmospheric escape]," he said. "The planet would be losing gas into space continuously. Can we stop that?"
If Earth is overpopulated, to imagine Mars as a home for millions of people or more would require "a place that can become habitable," Yiğit said, and continuous atmospheric escape just due to weather "is not our favor." There would eventually need to be a way to reverse the process via geoengineering that can artificially change the climate or the atmosphere, he continued.
The research letter, “Dust storm‐enhanced gravity wave activity in the Martian thermosphere observed by MAVEN and implication for atmospheric escape," was published on Feb. 2 in Geophysical Research Letters. The authors were Erdal Yiğit, George Mason University; Alexander S. Medvedev, Max Planck Institute for Solar System Research; Mehdi Benna, University of Maryland Baltimore County; and Bruce M. Jakosky, University of Colorado.