CNN
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The equatorial region of Mars is home to the solar system’s tallest volcanoes, which — in addition to being as tall as three Mount Everests in some cases — likely harbor an unexpected cold phenomenon, a new study has found.
The largest of these—Olympus Mons—is 16 miles (26 kilometers) tall and a whopping 374 miles (602 kilometers) in diameter, about 100 times larger than Earth’s largest volcano, Mauna Loa, in Hawaii. According to NASA, a Martian volcano could fit the entire chain of Hawaiian islands.
NASA/JPL/MSSS
The results of the study suggest that water can be found almost anywhere on the red planet’s surface, said lead author Adomas Valantinas.
These giants are topped by large calderas – bowl-shaped depressions caused by the collapse of the top of a volcano after an intense eruption.
The sheer size of the calderas – up to 75 miles (121 kilometers) across – creates a special microclimate within them. Using cameras mounted on probes orbiting Mars, researchers have observed for the first time morning frost forming inside calderas.
“Sediment forms at the bottom of the caldera, but we also see some ice on the rim. We also confirmed that it is ice and probably water,” said Adomas Valantinas, a postdoctoral researcher at Brown University who made the discovery as a doctoral student at the University of Bern in Switzerland and lead author of the study.
“This is significant because it shows us that Mars is a dynamic planet, but also that water can be found almost everywhere on the Martian surface.”
According to a study published Monday in the journal Nature Geoscience, a team of more than two dozen researchers recorded frost at four volcanoes: Arsia Mons, Ascraeus Mons and Ceraunius Tholus, as well as Olympus Mons.
The deposits are extremely thin—only one-hundredth of a millimeter thick, or one-sixth of a human hair, according to Valantinas—but they’re spread over such a large area that they form a lot of water. “A rough estimate is about 150,000 metric tons of water ice, which is the equivalent of 60 Olympic swimming pools,” he said.
To observe the deposits, the team first looked at about 5,000 images taken by the University of Bern’s CaSSIS — Color and Stereo Surface Imaging System — a high-resolution camera that has been photographing Mars since 2018. These include instruments aboard the ExoMars Trace Gas Orbiter, the space ship launched in 2016 as a collaboration between the European Space Agency and the Russian space agency Roskosmos.
“This is also the first discovery coming from CaSSIS, which is quite exciting,” Valantinas said.
The team verified their observations with two other instruments: NOMAD, a spectrometer also aboard the Trace Gas Orbiter, and HRSC, or High Resolution Stereo Camera, an older camera aboard ESA’s Mars Express orbiter, a spacecraft launched in 2003.
ESA/DLR/FU Berlin
This image of Olympus Mons was obtained early this morning (7:20 a.m. local solar time) by the stereo camera on board ESA’s Mars Express as part of new research that has revealed for the first time water frosts near the Martian equator – part of the planet. where it was thought impossible for frost to exist.
Valantinas says the discovery came with a degree of serendipity, as he originally looked for carbon dioxide frost but found none. The deposits have not yet been spotted because they only form during the early morning and in the cooler months, so the viewing window is narrow.
However, it is unlikely that human astronauts on Mars could one day harvest the frost. “It would be quite difficult because although it’s a large deposit, it’s also very thin and ephemeral, meaning it’s only there at night and early in the morning, then it sublimates back into the atmosphere,” Valantinas said.
The volcanoes are close to the equator of Mars, the planet’s hottest region, making the discovery of water particularly interesting, Valantinas said.
“Mars is a desert planet, but there is water ice in the polar caps and there is water ice in the mid-latitudes.” We also now have water frost in the equatorial regions, and the equatorial regions are generally quite dry. So it was quite unexpected,” he said.
He added that in the past, when Mars had a denser atmosphere and a different climate, there may have been glaciers on these volcanoes. The team now wants to expand the search for frost to all of the more than a dozen named volcanoes on Mars.
If humans are ever going to explore the Red Planet, we’ll need to know where the water is, so the water cycle on Mars is an important area of study, said John Bridges, a professor of planetary sciences at the University of Leicester in the United States. Kingdom, which was not involved in the study.
“This paper is a fantastic use of the ExoMars Trace Gas Orbiter’s CaSSIS camera, which provides both visible color and infrared light reflected from the Martian surface,” Bridges said, calling the results “a remarkable achievement.”
Additionally, the water cycle on Mars is not nearly as active as it was billions of years ago, making it challenging to measure how water moves across the surface, noted J. Taylor Perron, the Cecil and Ida Green Professor of Earth, Atmosphere and Atmosphere. Planetary Sciences at the Massachusetts Institute of Technology. Perron was also not associated with the new research.
“If the frost on these volcanoes is confirmed to be water (and not carbon dioxide), it would be surprising,” he said.
Everywhere on the surface of Mars is cold and dry, Perron added, but the region around the equator is drier and less cold than the poles, so it’s one of the last places you’d expect to see water frost. He reasoned that it would also raise the question of where the water vapor that forms the ice comes from—from volcanoes, even when dormant, or from much further away, such as the polar ice caps.