Sunday, October 25, 2009

Life On Mars? Methane 'Plumes' Raise Tantalizing Prospect Of Organisms On Red Planet

The tantalising prospect of finding life on Mars came a step closer today after Nasa discovered tell-tale ‘seasonal plumes’ of methane gas in the planet’s atmosphere.

The methane levels peak during the warmer summer months, providing the strongest hint yet that alien microbes could be thriving deep below the red, dusty surface.

Nasa scientists stressed there was still no direct evidence of extra terrestrial life - and that methane can also be produced by volcanic activity.

[ The surface of Mars may look dry and desolate but strange rock formations could suggest there was once water running there ]

However no active volcanoes have ever been spotted on the Red Planet.

On Earth 90 per cent of the methane in the atmosphere comes from living organisms.

While methane was found in the atmosphere in 2003, the new discovery of local hotspots of gas seeping from the ground during the warmer Martian summer raises the possibility that there are clusters of gas-producing microbes buried beneath the soil.

It will also allow future Mars probes to trace the source of the gas - and identify its origins.

British scientists last night welcomed the discovery, published in the journal Science.

Prof Colin Pillinger, the Open University scientist behind the failed Beagle 2 Mars probe in 2003, said: ‘Methane is one indicator of life - and this is more circumstantial evidence.

‘We only have methane on the Earth because it is pumped into the air by life now - or because it comes out of volcanoes.

‘The only way to prove it is produced by life on Mars is to go and have a look.’

Prof Andrew Coates, head of the Mullard Space Science Laboratory at University College London, added: ‘There are two basic scenarios and both are exciting. One is the possibility of life and the other of a geological process.

‘It’s a tantalising result, but it doesn’t prove life’.

Methane was discovered on Mars in 2003. Since then Nasa and European space craft have confirmed water vapour in the atmosphere and ice below the surface.

Lead scientist Dr Michael Mumma of Nasa said: ‘That was really exciting, but we knew that if we were to present the data to the scientific community it would have to be unassailable.

‘We would have to demonstrate not only that we were seeing methane, but that there really was no other explanation for it.

We know that every human on earth wants the answer to the question “Where did we come from and are we alone?” so it would be irresponsible to put out a claim that addressed this question without actually having an unassailable argument.’

[ Professor Colin Pillinger, who masterminded the unsuccessful Beagle 2 mission to Mars in 2003, said he believed the gas pointed to the existence of life on the planet ]

The source of the methane remains unclear and could be either micro-organisms living far below the Martian surface or volcanic activity, though volcanoes are not known to exist there.

‘If it were biological, it couldn’t be the higher life forms that we see on Earth because the surface of Mars is exposed to harsh ultra-violet light and low-density gases and so on,’ said Dr Mumma.

‘If this methane is a production of biology, it would be in the form of microbes underground where they may have access to water and other things needed to live, and where they are protected from the harsh surface environment.’

Such organisms are known to exist on Earth, living in the rock several miles below the surface in deep South African coal mines.

‘So we know that on Earth we have analogues that, if placed on Mars, could in fact prosper,’ Dr Mumma explained.

The latest findings were made using three telescopes in Hawaii. It was detected using specialist high-dispersion infra-red spectrometers - equipment that can reveal the chemical make up of gas on other planets.

Dr Mumma found plumes of methanes in regions of Mars’ northern hemisphere as it warmed during the Martian summer.

‘The methane we detected is of unknown age - its origin could be ancient or perhaps recent,’ he said.

Nasa is sending another probe to Mars in 2011. However, it will be poorly equipped to study methane and discover whether it comes from life.

The best chance to settle the life question will come in 2017 when Europe’s ExoMars robotic mission is due to land on the Red Planet.

[ The Phoenix Mars Lander, above and below, scooped up and tested soil samples that gave off water vapour. Water is seen as a pre-requisite for life on Mars ]

On Earth, methane made by decaying plants or found in the burps, belches and other emissions of animals from termites to cattle and people.

It is made up of carbon and hydrogen.

Mars is Earth’s neighbour in space.

It is further away from the Sun than the Earth and is smaller and colder.

Its thin atmosphere is mostly made up of carbon dioxide, with a little nitrogen, carbon monoxide and traces of oxygen and water vapour.

Water exists on Mars, and robot rovers have sampled ice from the surface. Scientists are eager to know how much more water is below the surface and whether it could support life now or in the past.

No known processes produce methane on the surface of Mars, and chemical reactions with compounds on the surface could break it down.

Nasa has a track history of talking up the possibility of life on Mars.

In 1996 it claimed to have found evidence of fossilised bacteria in a meteorite from the Antarctic that originated on Mars.

The claims of life were challenged by other scientists who said the unusual markings in the 4.5 billion year old rock could be the result of geological and chemical changes.

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