The search for life on Mars
The idea of life on Mars has captured the imagination since astronomers first thought they had found water-carrying canals crossing the planet.
HG Wells wrote his most famous book The War Of The Worlds about an invasion of Martians and the notion of Little Green Men inspired many films – such as the great spoof B-movie Mars Attacks!
But in 1996 the world was rocked by the announcement from the US space agency Nasa that they believed life probably did once exist on Mars. They claimed there was clear evidence of fossilised organisms in a meteorite from Mars found in Allan Hills, Antarctica.
The news inspired dramatic headlines such as “Life On Mars: Official” across the front page of the UK’s Daily Mirror newspaper.
It is probably safe to say that few today agree with Nasa’s early claims – the concensus appears to be that the meteorite could have been contaminated once it reached Earth.
Life on Mars made the front pages again in January 2009 when NASA reported the detection of plumes of methane coming from the surface of Mars. This could have a biological or geological origin and the experts are torn. It is clear that more investigations need to be carried out by future spaceprobes.
Some rather imaginative people believe there to be evidence of intelligent life inhabiting the Red Planet. Photos from spacecraft showing a face-like feature on Mars and shapes vaguely like pyramids inspired a rash of pseudo-scientific books claiming they had been built by aliens – but further images from space reveal clearly that they are natural rock formations.
How did the Allan Hills meteorite come to be on Earth? An asteroid struck Mars 16 million years ago, throwing a lot of Mars rock into space. It floated around the solar system before colliding with Earth 13,000 years ago.
Antarctica acts as a giant deep freeze, preserving meteorites that fall from space. Many have been found lying in the snow thousands of years after they fell.