What happened to water on Mars? – Brantford Expositor

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For most of the last couple of hundred years, people believed that Mars was inhabited.

Well-regarded astronomers thought they saw large structures on the planets surface that they ascribed to Martian civilization. These are the famous Martian canals.

The idea was that the inhabitants constructed a network of canals to carry water from the ice caps of Mars to the rest of the planet where it was needed. Of course, modern space probes have revealed that Mars is a dry planet and there were never any canals.

Our solar system is mostly composed of two distinct kinds of planets.

Gas giants, such as Jupiter, Saturn and the other outer planets, and terrestrial planets, such as Mercury, Venus, Mars and, of course, Earth.

If you are searching for life, you do not have a lot of choice in the solar system. Life as we know it must have three things: a solid surface to stand on, an atmosphere and a source of water. Of the terrestrial planets, Mercury is too small to hold an atmosphere and Venus is too hot for liquid water to exist on the surface.

Earth, of course, teems with life, so that leaves Mars as the only reasonable choice to find life. Unfortunately, Mars appears to be devoid of water.

Since Earth and Mars were formed by the same processes, why isnt Mars wet?

There are plenty of hints that Mars did have lots of water on the surface. We can see large geological formations that look just like similar water-created features on Earth.

We can see what look like meandering channels and deltas that resemble the formations at the mouths of rivers. Our robotic probes have found chemical evidence of water. When the surface was scratched by the robots, we saw what appeared to be water ice in the scrape.

As well, minerals were found that only could have been formed in the presence of water.

Today, it is pretty much settled that Mars, at one time, was wet. So, what happened to the water?

It appears a couple of different processes removed Mars water.

First, Mars lost its magnetic field. These fields are generated by liquid iron in a planets core. As the iron circulates, currents of electricity are generated and this creates a magnetic field that shields the planet from the action of the sun.

The sun spews huge amounts of charged particles from its surface every second. These particles stream out in all directions and sometimes strike the planets as they orbit the sun.

On Earth, the solar wind is deflected from the planet by its magnetic field.

Because Mars has no such magnetic shield, the solar wind strikes the planets atmosphere and, almost like sandpaper, strips it of molecules. Over billions of years, the atmosphere of Mars has been almost completely stripped away. By this process, any water in the atmosphere also would be stripped away.

This probably accounts for 10 per cent to 70 per cent of the water that was on Mars. The percentage depends on how much water the planet started with.

The rest of the water is almost certainly beneath the surface and chemically bound to rock layers. This happens on Earth, too, but our planet is volcanically active and the water is brought back to the surface.

The water on Mars might be available for humans to use if we colonize the planet, but it would be energetically inefficient to pry the water loose from the rock that it is bound to.

Only the future will tell if we can make Mars suitable for habitation.

Tim Philp has enjoyed science since he was old enough to read. Having worked in technical fields all his life, he shares his love of science with readers weekly. He can be reached by e-mail at: tphilp@bfree.on.ca.

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What happened to water on Mars? - Brantford Expositor