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Skywatching

How dry is Mars?

With Mars now the most intensively explored planet in the Solar System after ours, it is not surprising that we are continually having to review our ideas and preconceptions.

The Red Planet continues to challenge our imaginations.

The mainstream idea is that originally Mars had lots of water, but being a smaller world, with weaker gravity, and losing its magnetic field early on, its atmosphere and water got lost to space, leaving a cold, dry desert world.

Now, it looks as though we could be seriously wrong in our assumption that Mars is now a dried-up world.

Current estimates are that around three billion years ago, when life was first getting started in the Earth's oceans and possibly on Mars too, there was enough water on Mars to submerge the whole planet to a depth of between 100 and 1000 metres.

By comparison, if our Earth were a smooth ball, the existing oceans would cover it to a depth of well over 2000 metres. Mars once had a lot of water; by about a billion years ago, it had disappeared.

There are three places the Martian oceans could have disappeared to.

  • One is, as we know, the loss of water to space.
  • A second is the presence of lots of ice hidden underground, and possibly underground or under-ice briny lakes.
  • A third option is that water got taken up and combined with various minerals. This water is chemically tied up and can remain sequestered for a long time.

At some point in our high-school science career most of us have heated copper sulphate.

As we warmed it, those nice blue crystals turned into white powder and water came off as steam. Before we applied the heat the crystals were perfectly dry.

The water molecules were locked up inside the crystals as part of the chemical. There are many minerals that similarly lock up water.

The first rocks on Mars would have been volcanic. However, Mars, like Earth, was then a wet world, with rain and other weather.

On Earth, rocks are continually attacked and broken down, a process we call weathering. The situation on Mars would have been the same. In the process, minerals in the rock become new minerals that contain water, such as clays.

From observations done from orbit and on the Martian surface, it looks as though there is a lot of water tied up in hydrated minerals.

Apart from our interest in this information in helping us understand the history of the planet in the Solar System most like ours, it also is important regarding our plans to have long-term manned bases, or even colonies on Mars.

The red surface of Mars indicates iron oxides, which contain oxygen. In addition, we can use solar-generated electricity to liberate oxygen from water.

Given that current space technology means Mars is always many months away, the more self-sufficient our bases are for the key needs of energy, water and oxygen, the less dependent they will be upon Earthly support, and the more secure they will be in the long term.

Moreover, the more water there is, the better the long-term prospects of terraforming the planet.

Before messing with the Martian environment, we need to know whether there are living things on the planet. The last thing we would want to do is render their world uninhabitable to them.

The presence of water tied up in minerals rather than just frozen solid offers easier prospects for Martians to make a living, because water is an important component in extracting useful chemicals from their surroundings, maybe, as is the case on Earth, with the help of the Sun.

It is true that the solar ultraviolet radiation level on the surface of Mars is dangerous to us, but that radiation has a lot of energy in it, and there is no reason Martians, if any, will be like us.

  • Mars is high in the southwest after dark.
  • Jupiter and Saturn lie low in the southeast just before dawn.
  • The Moon will be New on the 11th.

This article is written by or on behalf of an outsourced columnist and does not necessarily reflect the views of Castanet.



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About the Author

Ken Tapping is an astronomer born in the U.K. He has been with the National Research Council since 1975 and moved to the Okanagan in 1990.  

He plays guitar with a couple of local jazz bands and has written weekly astronomy articles since 1992. 

Tapping has a doctorate from the University of Utrecht in The Netherlands.

[email protected]



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The views expressed are strictly those of the author and not necessarily those of Castanet. Castanet does not warrant the contents.

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