Life on Mars?

The year 2001 is just around the corner, but how close will life be then to how it was portrayed by Stanley Kubrick and Arthur C. Clarke in the epic film of the same name? The film showed a massive orbiting space station, communities on the moon, computers that can think and evidence of extraterrestrial life. It doesn't seem likely that we will reach such levels of technology in a matter of months, but can we ever expect people to live on other planets or encounter life elsewhere in the universe?

Within our solar system there is one place where man might live and even find other life - Mars. Ever since Italian astronomer Giovanni Schiaparelli thought he saw a planet-wide system of canals on Mars in 1877, people have speculated about the existence of intelligent life on the red planet.

Many books have been written and films made about the subject, possibly the most famous being H.G. Wells' The War of The Worlds, written in 1898 and featuring the invasion of Earth by Martians. But beyond the imagination of science-fiction writers and sensationalist filmmakers, is there any real chance of life on Mars and could we, Homo sapiens, ever hope to live there?

Vital statistics

From years of observation and more recent unmanned space probes we have developed quite a comprehensive picture of this, our most benign planetary neighbour. Like Earth, Mars has a twenty-four hour day but its year is about twice as long as ours, at 687 days. It travels in its orbit at a speed of over twenty-five kilometres a second and at its closest comes within 225.6 million kilometres of the sun. To give a picture of relative distances, it takes light from the sun eight light minutes to reach the Earth, but light from Mars arrives in only four-and-a-half, so it's about twice as close to us as our nearest star.

The planet's chemical makeup suggests a possibility of sustaining life. The atmosphere is composed mainly of carbon dioxide (95%) with oxygen at only 0.2%, but of course carbon dioxide can be broken down to produce oxygen. Another essential feature of life, water, is in evidence, but not as Schiaparelli imagined. The surface pressure of Mars is 0.6% of Earth's - if you could climb thirty-five kilometres into our atmosphere you would experience what it's like to walk on Mars. Temperatures vary extremely, with summer maximums of 17°C and polar regions dropping to a very freezing -123°C.

These conditions make it impossible for water to be found in a liquid state in most parts of Mars although there is water vapour in the atmosphere near the ice-caps in the Martian spring. There are, however, huge valleys and canyons, the most important being the Valles Marineris, over 4,000 kilometres long and sometimes as much as 600 kilometres wide and seven kilometres deep. This suggests that perhaps as long ago as the first third of its history Mars had substantial amounts of liquid water which may still exist below the surface. The greatest pointer to hidden water is the colour of the planet itself. It is red essentially due to the oxidation of iron- in other words it is rusty - and of course rust can't be produced without water.

So, although Mars would kill an unprotected human there are potentially the means to sustain life if they are technologically exploited. We are already in possession of the know-how to avoid the effects of low pressures and temperatures, to extract oxygen from carbon dioxide and find underground water. So, all in all, Mars would make for a more sensible place to live than our moon.

Journeys of discovery

The reasons why we haven't yet attempted to set up a manned Mars base are to do with the relative infancy of our manned space programme, which since 1968 has taken us no further than the moon, and the fact that there has been a mixed record in the success of the unmanned probes sent out to assess the potential of "Old Rusty". Most of our knowledge of Mars comes from the American projects; the first pictures coming from Mariner 4 in 1964, and then from Mariners 6 and 7 as they flew by in 1969. The first craft to orbit Mars was Mariner 9 which, after its launch in 1971, studied the planet from space for nearly a year. The first successful Mars landings were made in 1976 by two U.S. Viking craft, the first of which remained operational until 1982. Since then there have been failures - two Russian probes sent in 1988 both failed, as did the 1994 U.S. Mars Observer and the Russian Mars 1996 mission. More recently Climate Orbiter burned up over Mars in September 1999 and the Polar Lander, costing over $165 million, seems to have been lost too.

Alien sabotage?

Perhaps these losses were simply the result of bad technology, but people more inclined to the X-Files than pure science might speculate that they were not accidents. Maybe an advanced form of life exists there and chose to eliminate probes heading for sensitive areas so as to stay incognito. While there is no direct evidence to rule out that possibility, so far the only signs of life to be connected with Mars have been fossil traces of what would seem to be bacterial life found in meteorites from Alaska. Dating techniques applied to these samples age them to about the first 30% of the planet's 4.6 billion-year history.

Advanced or primitive, hostile or friendly, we aren't likely to get any answers for some time about the questions of life on Mars, nor are we in the foreseeable future likely to live there ourselves. As is so often the case with human endeavour, money is a crucial factor and after the recent failures, NASA will probably find funding hard to come by. Looking further into space, the kind of travel we see on TV sci-fi shows is out of the question for now, but our red neighbour is out there, within reach, waiting.

Steve Heighes