The most compelling evidence yet that liquid water exists on the surface of Mars was obtained by NASA’s Mars Reconnaissance Orbiter in pictures released on September 28th.
Mars missions over the last 20 years or so have established that vast oceans of water existed on its surface in the past but have subsequently dried up. Mars is smaller than the Earth and further from the Sun. It has therefore cooled down quicker and whereas the Earth retains a liquid core of molten iron the centre of Mars is solid. This means that Mars is no longer surrounded by a magnetic field. Our planet’s magnetic field protects the surface from harmful radiation and charged particles streaming from the Sun that are believed to have blown Mars’ atmosphere away.
Conditions on the surface were now thought to be too cold and at too low a pressure for liquid water to exist. Any liquid water present would, it was believed, quickly evaporate and escape into space. Why should water evaporate quickly on a cold planet? Surely evaporation depends on it being warm?
Everyone knows that water freezes at 0ºC and boils at 100ºC but this actually only applies to the conditions we normally encounter on the Earth’s surface. If we alter the pressure or add chemicals then these numbers change. Putting salt on the road or anti-freeze in our car’s coolant for example lowers the temperature at which water freezes, hopefully preventing skidding and burst radiators. The water on Mars appears to have been kept in a liquid state by similar processes to these.
The hottest liquid water on Earth is in the so called Black Smokers on the sea bed, at a temperature of over 400º, by contrast the surrounding oceans are at a temperature of around -10ºC.
The significance of these numbers is that wherever liquid water has been found on Earth so has life, no matter how inhospitable these places may appear to us.
The dry valleys of Antarctica are the most arid places on Earth. Blood Falls lies in one of these and is so called because the extremely salty water flowing from the tongue of Taylor Glacier contains so many red-coloured bacteria that it has the appearance of oxygenated blood.
The aptly if rather disgustingly named snottites live in deep caves, chemosynthesising volcanic sulphur and producing sulphuric acid as a waste product that is stronger than battery acid.
The density of living things around the black smokers mentioned above, including quite complex multicellular organisms, is 10-100 000 times that of the surrounding sea bed.
Some organisms meanwhile have adapted to the extreme cold, there are frogs and toads that can induce a rapid freezing of their body fluids, if they detect a drop in temperature, preventing damaging ice crystals from forming and allowing them to survive in solid ice until the Spring. Other animals have their own internal anti-freeze.
Living things have been found 11km below sea level at the bottom of the Mariana Trench at pressures 1100 times that on the surface, In solid rock 4km deep inside the Earth’s mantle and at the bottom of the misnamed Dead Sea, where the salinity is 34%.
The discovery of liquid water on Mars is therefore of enormous importance. We know that oceans of liquid water exist on Saturn’s moon Enceladus, Jupiter’s moon Europa and of course here on Earth. If liquid water also exists on Mars then, in the only solar system we have so far been able to study, liquid water exists on at least four planets or their moons. What limited evidence we have suggests that liquid water is ubiquitous in our Universe and, on the only planet we really know much about, wherever liquid water exists then so does life.
Paradoxically the discovery of liquid water has actually given the space agencies of Europe, Russia and America a fresh headache. International law, not to mention scientific and ethical considerations, prevent space probes from going to places where liquid water might exist in order to prevent contamination. We know that microbes can survive long journeys in space and the sterilisation techniques currently employed on space probes could not prevent introducing terrestrial organisms onto the Martian surface.
Nevertheless, planned missions by all these countries over the next couple of decades have a real chance of finding life on Mars if it exists and, as Dr Matthew Balme of the Open University has said:
“If we find life on Mars and it can be shown to be of a different origin to that on Earth, then that essentially means that the Universe is teeming with life. It seems almost impossible that life could spring up by chance on two adjacent planets if life was rare.”
In his wonderful book ‘Time’s Arrow Time’s Cycle’ the late Stephen Jay Gould describes the discovery of ‘deep time’ by the Scottish geologist James Hutton in the 18th Century. My father was a minister of religion and I have his old bible; it contains the dates worked out by Bishop Usher who, using the bible as his source, stated that the Earth was created at 6pm on the 22nd October 4004BC.
James Hutton showed that the Earth was by contrast unimaginably old.
The American writer Mark Twain said this about deep time:
“Man has been here 32,000 years. That it took a hundred million years to prepare the world for him is proof that that is what it was done for. I suppose it is. I dunno. If the Eiffel tower were now representing the world’s age, the skin of paint on the pinnacle-knob at its summit would represent man’s share of that age; & anybody would perceive that that skin was what the tower was built for. I reckon they would. I dunno.”
Certain scientific discoveries: that the Earth is not at the centre of space but just an insignificant part of a vast cosmos, that it formed billions of years before humans existed, that humans are not the product of divine intervention but the product of a process of evolution lasting aeons, these have fundamentally changed our view of ourselves.
The discovery that we are not alone, that life was, far from unique to the Earth, probably commonplace, would challenge many people’s deepest held beliefs, it would be, in every sense of the word, revolutionary. For that reason alone socialists should find these latest discoveries fascinating exciting and uplifting.