Ascent of Mars Mountain

Dr Duncan L Copp

May 2003

Mars has a special affinity with us on Earth. It's often cited as being most Earth-like of all the other planets in our solar system, but as many international robotic emissaries have shown, this is true up to a point. As Mars stands today it is a considerably hostile world for us to visit, and it may well be some time before we have the ability to climb the slopes of Olympus Mons.

Present Mars

A cursory glance at Mars will reveal a number of striking differences between it and our home planet. Mars has a very thin atmosphere, lacks liquid water, and has a distinctive orange-red colour. Although made from approximately 95% carbon dioxide (a dense gas compared to nitrogen and oxygen that constitute the bulk of Earth's atmosphere), the air pressure on the surface of Mars is almost 100 times less than on Earth. It's the equivalent of being 30km high on Earth – three times higher than the cruising altitude of a commercial airliner. Anyone exploring its surface would need to be cocooned in a pressure suit.

Your suit must also protect you from the dangers of space radiation. On Earth, our thick atmosphere shields us from the majority of high energy solar and cosmic particles which deluge the planet daily. These particles are so energetic that if the atmosphere were absent, they'd bore through our skin disrupting our delicate cell structure. The result would be an increase in harmful genetic mutations and a much higher risk of cancer. In fact, space radiation is one of the greatest hazards for astronauts venturing beyond Earth. But it's worse than that. Mars also lacks a substantial ozone layer. The ozone layer on Earth is all-important because it shelters us from the Sun's blistering ultra-violet light. On Mars, ultra-violet bathes and sterilises its surface and sunburn would be an acute problem if you were not guarded.

The lack of a substantial atmosphere results in a number of other inconvenient circumstances for the Earth visitor. First, it's cold down there. With no warming atmospheric blanket, temperatures typically hover around -63 C. Only in the lowest valleys during the warmest summer days do temperatures occasionally creep above freezing. Second, the low atmospheric pressure means water cannot remain liquid on the Martian surface. There's a golden rule in physics, the lower the atmospheric pressure, the lower the boiling point of water. That's why high on an Earth mountain an egg takes so long to boil – the water in which it's cooking boils at a lower temperature than at sea level. On Mars, the pressure is so low any liquid water brought to the surface instantly vaporises explosively. Water can only exist as solid ice as is seen at the poles of Mars, or in vapour form. Boiled eggs for breakfast would be a bad idea on Mars.

Today, the surface of Mars is an extremely cold desert. It shares features that are common with deserts on Earth. Its overall colour is red, owing to the abundance of iron minerals in the rocks and soils that have reacted with oxygen – effectively the surface has rusted over eons of time. Large dune fields are common and occasionally vast sandstorms sweep across the rock-strewn surface, blown by winds over a 100 miles an hour. The Martian atmosphere may be much thinner, but its gravity is only a third of that on Earth and dust particles are easily lifted and suspended. It's dust in the Martian atmosphere that gives it its characteristic pink sky.

Past Mars

There is an old adage in geological science, 'the present is key to the past'. This is particularly applicable on Mars. Although geologically dead today, Mars is littered with ancient volcanoes, valleys and dry channels that speak of times gone by when the planet was geologically dynamic. Travel back a few billion years and Mars would have been a world with erupting volcanoes and running water, perhaps enough water and atmosphere to sustain an ocean that harboured life.

Mars boasts the largest volcanoes in the solar system, the biggest being Olympus Mons. It towers 24km above the surface, three times higher than Earth's tallest volcano, Mauna Loa. Olympus Mons has a diameter half the size of Spain! These huge volcanoes are strikingly similar to the 'shield-shaped' volcanoes on Earth. The main difference is size – in every detail the Martian volcanoes are bigger. Why? On Earth the crust is made of a number of large plates which, driven by heat from below, shuffle past, ruck up and dive under each other – they are constantly on the move. Shield volcanoes on Earth can form when a plate moves over a hot spot, an area of hot upwelling material, hot enough to 'burn' a series of holes in the crust as it passes above. Each hole in the crust feeds a volcano. A good analogy is moving a piece of paper over a candle. On Earth the process is responsible for the formation of the chain of volcanic Hawaiian Islands, where the Pacific Plate is moving over a hot spot. However, on Mars plate tectonics never really got going. Here a hot spot would simply continue burning a larger hole in the same area of the crust, feeding the same volcano. Hence over time volcanoes the size of Olympus Mons formed.

From orbit you can see more evidence of Mars' active past. A vast canyon system running for roughly 3000km looms large along the Martian equator. This is Vhalles Marineris, a huge tear in the Martian crust. Such a feature on Earth would straddle the United States. Standing at it's edge would not be for the faint hearted – the cliffs either side form a 7km shear drop. Valles Marineris tells of a time when the crust of Mars creaked and groaned, driven by a hotter interior. Over billions of years, the Martian interior has cooled off quicker than our own molten core. This is because Mars being a smaller world loses heat more rapidly. Once the interior of Mars had cooled sufficiently, it no longer had the energy required to drive its geology. The crust stopped heaving and volcanoes stopped erupting.

Other evidence of a very different Mars comes from the numerous channels carved into the ancient surface. These features are remarkably reminiscent of river valleys on Earth, and are strong evidence that water once flowed here. It's likely that while Mars was geologically active, numerous volcanoes belched out a great deal of gases, creating a much thicker atmosphere than today. A thicker atmosphere and higher pressure would be far more favourable for Mars to support water on its surface in the past. But again, as the planet cooled and the eruptions ceased, the small planet was unable to hold on to its precious atmosphere, the majority was either gradually lost to space or seeped back below the surface.

Future Mars

What of Mars in the future? Is the planet destined to remain a lifeless sub-zero desert. Not if some scientists have their way. A number of detailed studies have looked into the possibility of resuscitating Mars to a point where it could support life. The process is known as terra-forming – metamorphosing Mars into an Earth-like world. The idea seems far-fetched, yet it has to be said that the planet contains all the ingredients to support life on its surface, it's just that these ingredients need to be redistributed.

First and foremost, the Martian atmosphere would need bolstering. Such padding could be supplied by releasing carbon dioxide trapped in frozen ice at the poles and locked within Martian rocks. Carbon dioxide is a potent greenhouse gas. Heat from the Sun is absorbed by the Martian crust and then re-emitted as infrared radiation, as on Earth. Carbon dioxide is very good at trapping infrared radiation – this is the infamous 'greenhouse effect' we're so conscious of on Earth. On Mars, however, greenhouse effect warming is essential if surface temperatures are to rise above freezing. This in turn would liberate any water in the crust and at the poles, which too would end up in the atmosphere.

Of course the problem is liberating the carbon dioxide. Various suggestions have been made including the controlled explosion of thermonuclear devices that could melt the Martian polar caps and change the chemical make-up of rocks – giving off carbon dioxide. Gradually, plant life could be introduced which would further help the thickening of the atmosphere of Mars by adding more carbon dioxide. Although this seems technologically possible, the terra-formation of Mars would take tens of thousands of years in practice. So let's not hold our breath!

Resources

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Websites

Mars history and geology

The Geological History of Mars
http://cmex.ihmc.us/Exo_Strat/Docs/state.html
A description of Mars geology and information on the planet's origins.

The Planet Mars: A History of Observation and Discovery
www.uapress.arizona.edu/onlinebks/
mars/contents.htm
Comprehensive online book covering the history of discovery on Mars.

Red Guide to Mars
www.amnh.org/rose/mars/cont2.html
A guide from the American Museum of Natural History, including a brief history and features about life on Mars.

Malin Space Science Systems
www.msss.com
High resolution images of Mars taken by the current Mars Global Surveyor Orbiter.

Hubble Telescope
http://hubble.stsci.edu
Regularly updated with downloadable photographic images of planets and the solar system.

Mars Daily
www.marsdaily.com
Newspaper-style website that allows you to catch up with what's been happening on Mars. Excellent articles about missions and technological discoveries.

Mars exploration

Nasa Official Site
www.Nasa.gov
Homepage of the US Nasa (National Aeronautics and Space Administration) organisation.

Nasa Space Flight
http://spaceflight.Nasa.gov
Looks at the space flight missions with articles about the people involved.

Nasa Mars Exploration Programme
http://mars.jpl.Nasa.gov
Information about the Mars exploration programme.

Planetary Data System
http://pds.jpl.Nasa.gov
Archives from all the US missions into space.

Beagle 2
www.beagle2.com
British-led effort to land on Mars as part of the European Space Agency's Mars Express Mission.

European Space Agency – Mars Express
www.esa.int/esaMI/Mars_Express/
Contains details and images of the Mars Express mission that set off on June 2 2003. The mission is ongoing.

The British National Space Centre
www.bnsc.gov.uk
Current information about Britain's development of space technology.

Living on Mars

A Crewed Mission to Mars
http://nssdc.gsfc.Nasa.gov/planetary/
mars/mars_crew.html
Nasa asks the question: Is it possible? Includes detailed analysis of how life support on Mars could work.

Living on Mars
www.marssociety.org.au/library
/Living_on_Mars.ppt
Online guide to living on Mars by the Mars Society Australia. Has tons of information, from what we would need to live on Mars to why it is the best choice of planet for colonisation.

Mars Colonization
http://library.thinkquest.org/C003763/
index.php?page=mars03
Article from Astrobiology with artist's impressions of how a Mars human colony could look and how it could function.

Thawing Mars
http://nai.arc.Nasa.gov/news_stories/
news_detail.cfm?ID=212
Nasa news story on how greenhouse gases might one day be used to warm the cold surface of Mars and make the planet habitable for humans.

SciForums.com
www.sciforums.com
There is continual forum debate on astronomy and cosmology with discussion on the exploration and possible colonisation of Mars.

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