Research team discovers frost on the highest volcanoes of the solar system PROVIDENCE, R.I. [Brown University] — An international team of planetary scientists has discovered patches of water frost on the peaks of the Tharsis volcanoes on Mars, which are the highest volcanic mountain masses not only on the Red Planet but in the entire solar system.

This discovery marks the first time that frost has been observed near the planet's equator, challenging existing perceptions of Mars' climate dynamics, according to a new study published in the journal Nature Geoscience.

Unexpected discovery
“We thought it was unlikely for frost to form around Mars' equator, because the combination of sunlight and thin atmosphere keeps temperatures relatively high on the surface and on the mountain peaks during the day — unlike Earth, where you can expect frosty peaks,” said Adomas Valantinas, a postdoctoral researcher at Brown University who led the work while a Ph.D. student at the University of Bern. “What we see could be a remnant of an ancient climate cycle on modern Mars, where precipitation and snow cover may have occurred on these volcanoes in the past.”

According to the study, the frost is present only for a few hours after sunrise before it evaporates in the sunlight. The frost is also extremely thin — probably only a hundredth of a millimeter thick or about the width of a human hair. Nevertheless, it covers a large surface area. Researchers estimate that the frost contains at least 150,000 tons of water that exchanges between the surface and the atmosphere each day during the cold seasons. This is equivalent to about 60 Olympic swimming pools.

Tharsis region
Tharsis, the region of Mars where the frost was found, contains numerous volcanoes. They rise above the surrounding plains to heights of one to twice the height of Mount Everest on Earth. For example, Olympus Mons is as wide as France.

The frost is located in the calderas of the volcanoes, which are large cavities at their peaks formed during past eruptions. Researchers suggest that the way air moves over these mountains creates a unique microclimate that allows thin patches of frost to form.

Modeling frost formation
Researchers believe that modeling how frost forms could allow scientists to uncover even more secrets of Mars, including understanding where water is located and how it moves, as well as understanding the complex atmospheric dynamics of the planet, which is crucial for future exploration and the search for possible signs of life.

Advanced technology used
Researchers discovered the frost using high-resolution color images from the Colour and Stereo Surface Imaging System (CaSSIS) on board the European Space Agency's (ESA) Trace Gas Orbiter. The findings were then confirmed by independent observations from the High Resolution Stereo Camera on ESA's Mars Express orbiter and the Nadir and Occultation for Mars Discovery spectrometer on the Trace Gas Orbiter.

The efforts included analyzing more than 30,000 images to initially find the frost and then confirm its existence. Valantinas filtered images based on where they were taken as well as when they were taken, such as the time of day and season. This methodical approach helped isolate spectral signatures indicating water frost and where it forms on the surface of Mars.

Valantinas began analyzing images in 2018. Most of the work was completed while he was earning his Ph.D. abroad, but part of the reanalysis was completed while he was at Brown University.

Further research
Transitioning to his role at Brown University, Valantinas now plans to continue investigating Martian mysteries as he turns to astrobiology. Working in the laboratory of planetary scientist Jack Mustard at Brown University, he will work on characterizing ancient hydrothermal environments that could have supported microbial life. Samples from these environments could one day be brought to Earth as part of NASA's Mars Sample Return mission.

“This idea of a second genesis, of life beyond Earth, has always fascinated me,” Valantinas said.

Source: Brown University