CNN
—
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 – are likely hiding an unexpected icy phenomenon, a new study has found.
The largest – Olympus Mons – is 26 kilometers high and a whopping 602 kilometers in diameter, making it about 100 times larger than the largest volcano on Earth, Mauna Loa, in Hawaii. According to NASA, the entire Hawaiian island chain could fit inside the volcano on Mars.
NASA/JPL/MSSS
The study’s findings suggest that water can be found almost everywhere on the red planet’s surface, said lead author Adomas Valantinas.
These giants are crowned by large calderas: bowl-shaped depressions caused by the collapse of the top of the volcano after an intense eruption.
The enormous size of the calderas – up to 121 kilometers wide – creates a special microclimate within them. Using cameras mounted on probes orbiting Mars, researchers have observed morning frost in the calderas for the first time.
“The deposits form at the bottom of the caldera, but we also see a bit of frost 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 candidate at the University of Bern, Switzerland, and the lead author of the study.
“It’s important because it shows us that Mars is a dynamic planet, but also that water can be found almost everywhere on the surface of Mars.”
The team of more than 20 researchers saw frost in four volcanoes: Arsia Mons, Ascraeus Mons and Ceraunius Tholus, as well as Olympus Mons, according to the study published Monday in the journal Nature Geoscience.
The deposits are extremely thin – just a hundredth of a millimeter thick, or one-sixth of a human hair, according to Valantinas – but they are spread over such a large surface area that they contain a lot of water. “Based on rough estimates, this is about 150,000 tons of water ice, the equivalent of 60 Olympic swimming pools,” he said.
To observe the deposits, the team first looked at about 5,000 images taken by CaSSIS – the University of Bern’s Color and Stereo Surface Imaging System – a high-definition camera that has been photographing Mars since 2018. It is one of the instruments on board the ExoMars Trace Gas Orbiter, a spacecraft launched in 2016 as a collaboration between the European Space Agency and the Russian space agency Roscosmos.
“This is also the first discovery of CaSSIS, which is quite exciting,” says Valantinas.
The team validated its observations with two other instruments: NOMAD, a spectrometer also on board the Trace Gas Orbiter, and HRSC, or High Resolution Stereo Camera, an older camera on board the ESA Mars Express orbiter, a spacecraft launched in 2003.
ESA/DLR/FU Berlin
This image of Olympus Mons was acquired in the early morning (07:20 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 frost near Mars’ equator – a part of the planet where it was thought that no monarch could exist.
Valantinas says the discovery came about with a degree of serendipity, as he was originally looking for carbon dioxide ice but found none. The deposits have not been noticed until now because they only form in the early morning and in the colder months, making the observation window narrow.
However, it is unlikely that the frost could ever be harvested by human astronauts on Mars. “It would be quite difficult because although it is a large deposit, it is also very thin and ephemeral, meaning it is only there at night and in the early morning, and then sublimates back into the atmosphere,” Valantinas said .
The volcanoes are located near Mars’ equator, the hottest part of the planet, making a water discovery particularly intriguing, Valantinas said.
“Mars is a desert planet, but there is water ice in the polar ice caps, and there is water ice in the mid-latitudes. Now we also have water frosts in the equatorial areas, and the equatorial areas are generally quite dry. So this was quite unexpected,” he said.
He added that in the past, when Mars had a thicker atmosphere and a different climate, there may have been glaciers on these volcanoes. The team now wants to expand the frost search to all more than a dozen named volcanoes on Mars.
If humans ever want to explore the red planet, we need to know where the water is, so Mars’ water cycle is an important area of research, says John Bridges, professor of planetary sciences at the University of Leicester in the United States. Kingdom, who was not involved in the investigation.
“This paper is a fantastic use of the CaSSIS camera on the ExoMars Trace Gas Orbiter, which reflects both visible color and infrared light from the surface of Mars,” Bridges said, calling the results a “remarkable achievement.”
In addition, the water cycle on Mars is not nearly as active as it was billions of years ago, so measuring how water moves across the surface is a challenge, noted J. Taylor Perron, the Cecil and Ida Green Professor of Earth, Atmospheric and Planetary Sciences at the Massachusetts Institute of Technology. Perron was also not involved in the new research.
“If it is confirmed that the frost on these volcanoes is water (and not carbon dioxide), that would be surprising,” he said.
Everywhere on Mars’ surface is cold and dry, Perron added, but the area 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. It would also raise the question, he concluded, of where the water vapor that forms the frost comes from – from the volcanoes, even if they are inactive, or from much further away, such as the polar ice caps.