Spotted! Water frost on Mars volcanoes for 1st time

Frost on Mars volcanoes: Large rounded mountain seen from above, with craters on top.
View larger. | Olympus Mons on Mars is the largest volcano in the solar system. This view is from Mars Express. A new study of images from the Trace Gas Orbiter (TGO) spacecraft reveals water frost on Mars volcanoes for the 1st time. Image via ESA/ DLR/ FU Berlin/ University of Berlin.
  • For the first time, scientists have found water frost on Martian volcanoes. ESA’s Trace Gas Orbiter spacecraft discovered the frost on the huge Tharsis volcanoes, including Olympus Mons.
  • The coatings are only about the thickness of a human hair. But the daily amount of frost covers such a large area that altogether it could fill 60 Olympic swimming pools.
  • The water in the frost could be a valuable resource for future human missions to the red planet.

Water frost found on Mars

Frost is one of the few forms of water that still exists on the surface of Mars. Orbiting spacecraft have seen it from high above and landers and rovers have sometimes come across it right on the ground. Now, for the first time, orbiters have spotted frost on Mars volcanoes, specifically the massive Tharsis volcanoes, including Olympus Mons. On June 10, 2024, an international team of researchers said the European Space Agency’s Trace Gas Orbiter (TGO) spacecraft found the frost.

The team, led by Adomas Valantinas at the University of Bern in Switzerland, published their peer-reviewed findings in Nature Geoscience on June 10, 2024.

Frost on Mars volcanoes is a surprise

While water frost has been seen on Mars before, it has never been detected on the giant volcanoes in the Tharsis region, until now. Even though the volcanoes are massive, reaching up to 16 miles (26 km) in height, scientists didn’t expect to find frost on them. That’s because they are at low latitudes, close to the Martian equator. Valantinas said:

At these low latitudes, the high amounts of sunshine tend to keep surface temperatures high. Therefore, we did not expect frost to be found there.

But it was there. The thin atmosphere also plays a role. It doesn’t cool the surface very well, so at midday, surfaces at high altitudes can get just as warm as those at low altitudes. That is the opposite of what happens on Earth.

Valantinas elaborated:

Upslope winds bring air containing water vapor up from the lowlands, and this air cools as it gets to high altitudes, causing condensation. This is a familiar phenomenon both on Earth and on Mars. As we could see from the CaSSIS images, the thin frosts are only present briefly, for a few hours around sunrise, before they evaporate in the sunlight.

Bluish terrain with many meandering ridges and cracks.
High-resolution (4.5 meters/pixel or 15 ft/pixel) CaSSIS color image of frost on the caldera floor and northern rim of Olympus Mons. Frost is absent, however, on the steep sunlit slopes. Image via ESA/ TGO/ CaSSIS / University of Berlin (CC BY SA 3.0 IGO).

CaSSIS images reveal frost on Mars volcanoes

The researchers made the discovery using images from the Color and Stereo Surface Imaging System (CaSSIS) on the Trace Gas Orbiter spacecraft. Overall, the research team analyzed more than 5,000 images. Previously, CaSSIS has spotted movements of dust, dry avalanches and changes in deposits of carbon dioxide ice. Now frost can be added to that list. Co-author Nicolas Thomas at the University of Bern said:

That we now could detect the nighttime deposition of water frost on Mars at visual wavelengths and at high resolution is yet another proof of the impressive scientific capabilities of the Bern camera system.

In addition, the High Resolution Stereo Camera (HRSC) onboard ESA’s Mars Express orbiter and the Nadir and Occultation for Mars Discovery (NOMAD) spectrometer onboard the TGO spacecraft helped to confirm the findings. As Ernst Hauber, a geologist at the DLR Institute of Planetary Research in Berlin, Germany, noted:

This study nicely demonstrates the value of different orbital assets. Combining measurements from various instruments and modeling, we can improve our understanding of atmosphere-surface interactions in a way that wouldn’t be possible with one instrument alone.

Volcanic origin?

The paper also noted that the frost is unlikely to be volcanic in origin:

Given the unlikely seasonal nature of volcanic outgassing, we suggest the observed frost is atmospheric in origin, implying the role of microclimate in local frost formation and a contribution to the broader Mars water cycle.

It is conceivable that dormant volcanoes can emit carbon dioxide, water vapor and minor amounts of sulfur dioxide via diffuse outgassing from the regolith [soil]. If the observed water frost deposits are of volcanic origin, their distribution may constrain models for present-day outgassing from the interior. However, on Mars, sulfur dioxide has not been detected, and no thermal hotspots have been found. A volcanic source for the condensate cannot completely be ruled out … Consequently, we conclude the newly detected frosts on Tharsis volcano calderas are probably of atmospheric origin.

Brownish rocky terrain with white frost and hazy reddish sky.
View larger. | NASA’s Viking 2 lander captured this view of water frost in Utopia Planitia on May 18, 1979. Image via NASA/ JPL/ Ted Stryk/ The Planetary Society. Used with permission.

A significant amount of water

The coatings of frost on Mars volcanoes are thin, only about 1/100 of a millimeter. That’s the width of a human hair. That sounds pretty minuscule. Yet, the frost covers so much terrain, it still adds up to a significant amount. Valantinas said:

The amount of frost represents about 150,000 tons of water swapping between surface and atmosphere each day during the cold seasons, the equivalent of roughly 60 Olympic swimming pools.

Could that be enough to sustain microbial life? Possibly, but the surface conditions are still brutally cold with only a whisper of an atmosphere. Most scientists think if there are any microbes on Mars, they are most likely below the surface.

A future resource

The water could still be an important resource for future astronauts, however. Thomas said:

Understanding where water can be found, and how it moves between reservoirs, is relevant for many aspects of Mars exploration.

Valantinas added:

Of course, we want to understand the physical processes involved in the climate of Mars. But, in addition, understanding the water cycle on Mars is also of major importance for establishing key resources for future human exploration and to constrain the past or present habitability.

NASA’s Viking 2 lander, which landed in Utopia Planitia on September 3, 1976, also sent back photos showing coatings of water frost on the rocks and sand. The iconic image shown above clearly shows the white frost on the brownish/reddish terrain. Viking 2’s companion lander, Viking 1, touched down in Chryse Planitia on July 20, 1976.

Bottom line: For the first time, an orbiting spacecraft has detected water frost on Mars volcanoes. The daily amount of frost could fill 60 Olympic swimming pools.

Source: Evidence for transient morning water frost deposits on the Tharsis volcanoes of Mars

Via University of Bern

Read more: Miles-thick buried water ice at Mars’ equator?

Read more: Scientists find water in Mars’ Grand Canyon

June 16, 2024

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