Lab Experiment Emulates Mars’s Boiling Water

We all know that Mars is a dry and dusty planet that, nonetheless, has hidden sources of water. None of it flows on the surface in a stable way — that is, it doesn’t move in rivers or pool in lakes anymore. The water that DOES exist is underground. When it somehow reaches the surface, the temperatures and pressures produce boiling water. The action of the water is so intense that it can set off dry avalanches and blast sediments out to the surface.

How can Mars water boil if the surface temperatures are cold? As anybody who has taken a physics or chemistry class would immediately recognize, water’s boiling point isn’t just dependent on temperature. It is also affected by atmospheric pressure. Here on Earth, the atmospheric pressure at sea level allows water to boil at 100 C (212 F). Where I live (at 9200 feet or 2818 meters), the water boils at 90 C (194 degrees F). The higher the altitude, the lower the air pressure, and the lower the temperature needed to boil water on Earth.

On Mars, the atmospheric pressure is so low that water can boil at as low as 0 C (32 F). Most of Mars’s water is frozen underground, but it can be warmed up enough during the Martian summer and spring that water will start to flow from underground and boil when it reaches the surface. And, according to some research done here on Earth by a group of scientists in Paris, France, the boiling action may be enough to explain some Martian surface features seen in high-resolution images.

Reproducing Mars on Earth

The scientists used a decompression chamber to simulate various atmospheric conditions where water flows. The flows produced in conditions that we see here on Earth produced water flows that simply seeped into sand. Once the water dried, there was no trace it had ever been there. However, when they dialed in the conditions for Mars and plugged in a small ice cube beneath the sand, the water produced by the melting ice started to boil as soon as it reached the surface. It also released gases, which caused the ejection of sand grains. They formed small ridges at the front of the flow. Over time, those ridges became unstable and actually produced avalanches of dry sand. The process was even more violent at lower pressures. The entire process left behind a series of ridges very similar to what is seen on Mars.

Of course, the action of boiling water is only one way that ridges form on the Red Planet. The wind plays a role in creating dunes and ridges, as well. However, this experiment also shows that more than one process is at work on Mars, and there are likely others, too.

Until we can actually get to Mars ourselves and do more in-depth chemical and physical studies of the ridges and dunes scattered across the planet, experiments such as these help us understand what we’re seeing on the Red Planet. For a planet without surface water, it does seem that the appearance of Mars really does owe a lot to the action of water.

Blame it On the Tilt

Staying on the topic of Mars this week, there’s a look at a new way of looking at the Red Planet’s ancient past. We all know that Mars’s history has been an enigma for scientist, even as they learn more about it through robotic explorations. Still, after more than 50 years of space missions to Mars, we have questions. Where’s the water? Where WAS the water? When did it flow? What made it flow? Was there a cataclysmic event that changed the face of the planet forever? As it turns out, maybe there’s an idea that helps answer all those questions.

A group of French scientists blames a gigantic structure called the Tharsis Bulge for some of Mars’s most impressive mysteries. They say that Mars experienced a curious “tilt” between 3 and 3.5 billion years ago. It wasn’t an axial tilt,  but a shift of the outer layers of the planet (the mantle and crust). They somehow “slipped” around the inner core. That introduced huge changes to the surface that make Mars what it looks like today.

What Caused The Mars Tilt Catastrophe?

A band of scientists using the sciences of geomorphology, geophysics and climatology used observational data from current Mars to explain the Mars of the past.  (The team was based at Géosciences Paris Sud (CNRS/Université Paris-Sud), Géosciences Environnement Toulouse (CNRS/Université Toulouse III) and the Laboratoire de Météorrologie Dynamique (CNRS/École polytechnique/UPMC/ENS), together with a researcher from the Lunar and Planetary Laboratory (University of Arizona, U.S.)

Here’s the sequence as the group described it: the gigantic Tharsis volcanic dome began to form nearly 4 billion years ago. It was first located at 20 degrees north latitude (about the location of Hawaii on Earth). It grew taller and wider from repeated volcanic eruptions. Eventually the flows formed a 5,000-kilometer-diameter plateau. (That’s about 3,400 miles, or about the width of North America). This huge volcanic dome was about 12 kilometers deep (about 7.5 miles, or taller than Mt. Everest on Earth), and was extremely massive. Think billions of billions of tons of volcanic deposits distributed in a relatively small part of the planet. That huge mass of rock unbalanced the crust and caused it to shift around. This “Tharsis  bulge” migrated to the equator where it lies today, and that shift moved the polar crust, too.

So, if such a shift happened, and the geological evidence may well show that it did, it rearranged the Martian topography. The same theoretical study that speculates on that shift, also shows that Martian rivers containing water from precipitation and ice melt could have flowed at the same time as the formation of the Tharsis bulge.  That would make sense, given that climate models from the Laboratoire de Météorologie Dynamique showed a colder, wetter climate with a denser atmosphere than we see today.  That would have allowed ice accumulations (such as those suspected to have existed at around latitude 25°S, for example) to melt in response to volcanism, and for water from both the melt and precipitation to flow and create the dry river beds we see today.

So, What Happened to Mars?

Put all these studies together, and you get a slightly different history of Mars of about 3.5 billion years ago. You have a period of liquid water stability that allowed the formation of river valleys on Mars at the same time as the volcanic activity of the Tharsis dome. In fact, the building of the dome may have caused the formation of the river valleys due to volcanic melting of ice. Then, for some reason, the fluvial activity ended some 3.5 billion years ago, and the great tilt triggered by Tharsis’s great heft and influence on the planet took place. That shifted the dome and the poles, and changed the look of the Red Planet.

Since this theory is based on observed geology of Mars, the new geological explanation should be a useful factor as planetary scientists speculate about early Mars and the possibility of life that may have existed in an ancient ocean. I would imagine that these ideas would also help guide future Mars explorers when they get to the Red Planet to study its rocks, plains, mountains, and former oceans, rivers, and lakebeds.