A seasonal imbalance in the amount of solar energy absorbed and released by the planet Mars is a likely cause of the dust storms that have long puzzled observers, a team of researchers report.
The extreme imbalance in Mars’ energy balance (a term referring to the measure of solar energy a planet receives from the sun and then releases as heat) has been documented by University of Houston researchers Liming Li , Associate Professor of Physics; Xun Jiang, professor of atmospheric sciences; and Ellen Creecy, PhD student and lead author of a published article in the Proceedings of the National Academy of Sciences (PNAS).
“One of our most interesting findings is that excess energy – more energy absorbed than emitted – could be one of the generating mechanisms of Mars dust storms. Understanding how it works on Mars could provide clues to the roles that Earth’s energy budget plays in the development of severe storms, including hurricanes, on our own planet,” Creecy said.
A thin atmosphere and a very elliptical orbit make Mars particularly sensitive to large temperature differences. It absorbs extreme amounts of solar heat as it swings closest to the sun in its perihelion seasons (spring and summer for Mars’ southern hemisphere), which is the same extreme part of the orbit when its dust storms appear. As its orbit moves Mars away from the sun, less solar energy is absorbed by the planet. This same phenomenon also occurs on Earth, but researchers have found it particularly extreme on Mars.
On Earth, energy imbalances can be measured by season and year, and they play a crucial role in our global warming and climate change. In a separate project, Creecy and his colleagues are examining whether the energy imbalance on Mars also exists on longer time scales, and if so, what the implications for the planet’s climate change would be.
“Mars is not a planet with real energy storage mechanisms, like we have on Earth. Our great oceans, for example, help balance the climate system,” Creecy said.
Yet Mars bears signs that oceans, lakes and rivers were once plentiful. So what happened? The facts are unclear as to why or when the planet dried up into a hot, dusty globe with an abundance of iron oxide – rust, in fact, whose tawny color inspired observers to centuries ago calling it the red planet.
“Mars had oceans and lakes in the past, but then it experienced global warming and climate change. Somehow Mars lost its oceans and lakes. We know that climate change is happening on Earth right now. So what are the lessons of the Mars experiment for Earth’s future,” Li asked.
Creecy and his colleagues reached their conclusions by comparing four years of data (that’s Martian years, or roughly the equivalent of eight Earth years) of Mars’ orbits and temperatures to conditions documented by the missions. from NASA.
For planetary enthusiasts, they note that much of the data is freely available on NASA’s Planetary Data Systems website, although some information is only available to researchers. They also collaborated with NASA scientists, including several who have been key members of past missions, including the Mars Global Surveyor and two rovers, Curiosity and Insight, which still operate there.
“If we open our eyes to a wide field, the Earth is only one planet. With a single point, we can never have a complete picture. We have to look at all the points, all the planets, to have a complete picture of the evolution of our own Earth. There are many things we can learn from other planets,” Li said. “By studying the history of Mars, we gain a lot. What is climate change? What is the future phase of our planet? What is the evolution of the Earth? So many things we can learn from other planets.
Joining Creecy, Li and Jiang as co-authors on the paper were Michael Smith of NASA Goddard Space Flight Center in Greenbelt, MD; David Kass and Armin Kleinböhl, both of the Jet Propulsion Laboratory at the California Institute of Technology; and Germán Martínez of the Lunar and Planetary Institute in Houston.
– This press release originally appeared on the University of Houston website