Date: 31 March 2004
Subject: Water and Life on Mars

Martian life has always been a source of science fiction, and water central to ideas of Martian life. In 1858 Fr Pierre Angelo Secchi made some observations, showing mottled green patches on a pink background. In his 1863 colour map of the planet he labelled certain vague streak-like features he observed as "canali". or "channels".


The eminent Italian astronomer Giovanni Schiaparelli (1835-1910) used the same term as he produced his map of Mars. Actually Schiaparelli was colour blind and effectively produced a chart rather than a picture – albeit the "canali" do look very regular and sharply defined.

The words "canali" just means "channels", but when the American Percival Lowell referred to them the word "canals" implied a conscious design origin. Lowell began from a kind of Spencerian social Darwinism, more Lamarckian than really Darwinian, with notions of an upward thrust of life. A view that life, even intelligent life, existed elsewhere was certainly not, however, anti-Christian, indeed it was the dominant view amongst Christians (even those sceptical of Lowell). Lowell, however, saw the seasonally changing polar caps of Mars as remainders of ice sheets, and the canals as the attempts of intelligent Martians to preserve and distribute the remaining water in a planet which was gradually losing it. Astronomers divided between those who could "see" the canals and those who couldn't. The idea, however, inspired generations of sci fi writers, including H.G.Wells in his famous "War of the Worlds".

Late 20th century work proved that there are no large scale canals on Mars, but speculation has remained as to whether or not there was or at least had been water there. NASA aimed their 2004 space mission to see if their rover could find out, eg, whether its target site was a one time lake bed or just somewhere covered in volcanic ash. Now the data sent by the NASA rovers seem to have shown that there once was indeed water on Mars. The rover Opportunity has found various things which make it look as though there was water, in particular finding an unusual amber-yellow-brown mineral made of potassium iron sulfate hydroxide (jarosite) which apparently forms only in water.

If there was, indeed, water, then possibly there could have existed at least the kind of microbes that are thought to have once dominated terrestrial life. In purely scientific terms we really have little idea how likely this would be. Since we know very little about any exact biochemical path which could have led step by step to our existing DNA based replicating life forms, assessing its likelihood "by chance" is very difficult. Those who simply assume that it "must have happened" have little basis for it.

On the theological level we also have little to guide us. The most common Christian view in the nineteenth century (taken eg by David Brewster) was that God would not have created so vast a universe just to leave it empty – so there very probably were other life forms on other planets, elsewhere if not in our own solar system. Scripture, however, really does not indicate anything one way or the other. Perhaps God, as C S Lewis famously put it for Aslan in his Narnia books, would simply say "I tell no one any story but their own". To us it is of interest in itself, but has no obvious theological implications one way or the other.