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Mars is the second closest planet to the Earth (Venus gets closer), and in many ways is the nearest to the Earth in conditions.  It is also the obvious place for the first genuinely self sustaining Human colony off this planet.


Mars has about a tenth of the mass of the Earth; its gravity is a bit over a third of the Earth’s.


The atmosphere of Mars is much thinner than that of the Earth, having a little less than a hundredth of the air pressure.  The air of Mars contains about 95 percent Carbon Dioxide, and 2.7 percent Nitrogen. There are smaller amounts of several other gases including a small amount of free Oxygen and some water vapour and a little bit of Methane.  There is also some Carbon Monoxide which is poisonous to us although not to all life, and several inert gasses like those on the Earth.


Mars is colder than the Earth.  At the Martian poles, the temperature certainly drops to minus 143 degrees C (minus 225 degrees F).  This compares with the coldest temperature ever recorded on Earth (At Vostok in the Australian Antarctic Territory) of minus 89 degrees C.

The hottest the surface of Mars gets at the equator is around 27 degrees C in the summer(80 degrees F), but the air temperature is practically always below freezing point.

Orbit and Seasons

Mars has a similar axial tilt to the Earth and has seasons, but because the Martian year is nearly twice as long as the Earth’s, the seasons are longer.  The Martian day is only a little bit longer than the Earth’s day.

Magnetic field

Mars does not have a strong magnetic field like the Earth’s although there is evidence that in the past it had one.  This means that the surface of Mars has much less protection from some of the more damaging particles from the Sun.


Mars has less water than the Earth, but still has substantial amounts.  However, the water is not liquid on the surface.  We cannot rule out liquid water underground, and there are a number of things that suggest it is likely.

The water is mainly in the form of ice although there is water vapour in the atmosphere as well.

Evidence for Life on Mars

We do not know if there is life on Mars.  Certainly no proof that life even exists on any place except the Earth has been found.  There is evidence of life, but different people interpret it in different ways.


The Martian atmosphere contains about 10 parts per billion of Methane.  Methane in the  Martian atmosphere will be destroyed over a period of a few hundred years.  This means that something is replacing it.  Several theories have been suggested to explain where the Methane is coming from. 

Methane producing bacterial are certainly one possibility.  To me is seems significant that the main places the Methane is coming from are the areas with definite indications of liquid water in the past.


In 2004 the Mars Express spacecraft detected Ammonia(NH3) in the atmosphere of Mars.  Ammonia would only last for a few hours in the atmosphere of Mars, so if it was there, something had produced it.  Again there are several theories about where it came from, but to me the most plausible one is bacterial action.

Although Mars has all the elements necessary for life as we know it, they are certainly present in different proportions compared with the Earth.  One important element is Nitrogen.  This is part of all proteins and nucleic acids.  Mars has Nitrogen.  The atmosphere has a 2.7 percent Nitrogen.  This is much less than the Earth, so Martian living organisms may be more careful to retain its Nitrogen than those on the Earth.  If the presence of Ammonia in the atmosphere is confirmed, it may be very important.


Roughly one in a thousand of the meteorites found on the Earth are from Mars.  A meteorite hitting Mars can knock small pieces of the planet into space and some will go to other planets.  Rocks can also be ejected into outer space by volcanoes.  Structures have been found in at least three Martian meteorites which have been interpreted as evidence of life on Mars in the past although this is still being argued about.

The places on the Earth with the most similar condition to those of parts of Mars are dry valleys in Antarctica.  These do have life, but detecting it is not as easy as in other places.  These valleys are actually colder than the warmer parts of Mars, so the low temperatures of Mars are not an absolute bar to life.

Although the lack of a Martian magnetic field means that the surface is being bombarded with damaging particles from the Sun, this only applies to the exposed surface.  Underground life would be protected, even if it was only a couple of millimetres deep it would have some protection.

Although the conditions for life as we know it are not as good on Mars as on the Earth, the Martian conditions certainly allow for some life to exist.  This does not prove that it is there, but I am inclined to think that Mars does have life.

Where could Martian Life have come from?

There are two obvious possibilities.  Martian life could have formed in the first half billion years or so of the planet’s existence when the conditions were quite different those of today, or life could have come from somewhere else.

We know that the planet closest to Mars has abundant life, including very tough underground life.  A meteorite could have been knocked off the Earth by an impact, or ejected by a volcano, and bacterial could have survived the journey to Mars.  Although this sounds like an unlikely thing to happen in any one century, we have increasing evidence that this is possible, and there have been a huge number of centuries for it to happen.

Manned Exploration of Mars

The enormous cost of travelling to Mars certainly puts governments off the idea.  The cost has been variously estimated, but it certainly could be a Trillion Dollars or more.  Is it worth it?  Personally I think it would be worth even this huge cost, but there is a cheaper way.  Robert Zubrin suggested one in his book "The Case for Mars: The Plan to Settle the Red Planet and Why We Must".  This book was written in the 1990’s, but the basic ideas are at least as valid now as they were in 1990 when he was investigating the idea.

Mr. Zubrin was not suggesting any new technology; in fact he made the point that we were capable of going to Mars after 1969 when men landed on the Moon.

 Make your own Fuel

By sending an automatic plant to Mars to manufacture fuel for the return journey, you have immediately saved a huge amount of weight in what you send to Mars.  If you have power, rocket fuel can be made using material easily available on Mars.  All the elements are there; Carbon and Oxygen from the Carbon Dioxide in the atmosphere, Hydrogen and Oxygen from water in the soil, assuming you land the plant over an area with water.

Liquid Hydrogen it not easy to store for long periods, but you can easily get round this problem by using Methane as your fuel.  Although this is not quite as efficient as Hydrogen, the escape velocity of Mars is much lower than the Earth’s, so you do not need as much power to leave the planet.

Although Mr Zubrin suggests sending a small nuclear reactor to Mars, I would also be looking at the possibility of using solar cells as the power source.  On Mars, one square metre of reasonably efficient solar cells should produce about 100 watts of electricity during the Martian day. To equal the 100 Kilowatts envisaged by Mr. Zubrin would need about 2000 square metres of Solar Cells.  This is a large area, and you would need some sort of automatic system of setting them up.  Although there are problems with this, it would be an alternative if people object to the idea of sending a Nuclear reactor into space.

If you had less power, you could still make the fuel, but more slowly

Of course once you have your fuel making plant on Mars, it can be used for many return missions as well as providing power and Oxygen for your people on the planet.


Although you have saved many of the costs of sending a manned mission to Mars, this would still be expensive.  In fact it could easily cost you as much as a tenth of the present estimates of going to Mars.

Mars at its close approach to the Earth on October 28, 2005
Picture taken with the Hubble Space Telescope.
It was it was created by NASA and ESA.
Ice Clouds on Mars
This Picture was taken by NASA's Mars Pathfinder.
Hypothesised History of Water on Mars
Images created by NASA.
Mars meteorite EETA79001.
Photograph by NASA
Scanning Electonmicrograph of the Surface of a Martian Meteorite.
This picture by NASA is of a Metoerite from Mars recovered from Antarctica by the Japanese polar team.
NASA's Oppotunity rover found strong evidence that Mars was wet in the past.
A drawing of a proposed NASA Martian Descent/Ascent vehicle.