Evidence builds for life on Mars

 

A team of UK scientists have produced powerful new evidence that life may still exist on Mars. Their research reveals that swamp gas detected in the martian atmosphere can NOT be caused by meteorites hitting the red planet.

Mars photographed by the Hubble space telescopeRuling out that theory boosts NASA’s suggestion that the methane gas is being given off by living organisms.

The UK experiments were carried out by a team at London’s Imperial College. Their results are published tomorrow in the journal Earth and Planetary Science Letters.

Methane can only last a limited time of a few hundred years in the atmosphere of Mars before it is destroyed by sunlight.

The puzzle facing scientists therefore is that it must be constantly replenished by an unknown source – which many believe must be a simple form of life.

Mars is regularly hit by meteorites from space. The Imperial College team checked whether the methane could be produced by intense heat on the space rocks as they entered the martian atmosphere.

But laboratory tests recreating this searing bombardment failed to produce high enough levels of methane. They heated meteorite fragments to 1,000° C and then used a device called a spectrometer to measure the gases given off.

This showed that meteorites can only account for 10 kg of methane a year – way below the 100-300 tons needed to top up the levels of methane that are observed in the martian atmosphere.

Co-author of the new study, Dr Richard Court, said: “Meteorites vaporizing in the atmosphere are a proposed methane source but when we recreate their fiery entry in the laboratory we get only small amounts of the gas. For Mars, meteorites fail the methane test.”

The only alternative explanation now is that the gas is produced by volcanic rock reacting with water on Mars. But the UK team says that previous studies have ruled out volcanism as a cause.

Professor Colin Pillinger, of the Open University, who was behind Britain’s ill-fated Beagle 2 mission to Mars in 2003, says he does not accept a volcanic explanation.

He points out that the plumes of methane announced by NASA in January are not being produced in areas where there are volcanoes. He told Skymania News: “Methane is a product of biology. For methane to be in Mars’ atmosphere, there has to be a replenishable source.

“The most obvious source of methane is organisms. So if you find methane in an atmosphere, you can suspect there is life.”

Now scientists are keenly awaiting a joint NASA/European probe to Mars in 2018 to dig for direct contact with any mini-Martians. The Imperial team have developed instruments to extract organic material from martian rocks.

Professor Mark Sephton, of Imperial College, said: “As Sherlock Holmes said, eliminate all other factors and the one that remains must be the truth. The list of possible sources of methane gas is getting smaller and excitingly, extraterrestrial life still remains an option. Ultimately the final test may have to be on Mars.”

Last week, a NASA team produced images of what they claim is a colony of martian bacteria in a meteorite kept at London’s Natural History Museum, boosting the idea that alien organisms were brought to Earth from Mars.

• Discover space for yourself and do fun science with a telescope. Here is Skymania’s advice on how to choose a telescope. We also have a guide to the different types of telescope available.

 

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  • Daniel Fischer

    There was a big conference on the Martian Methane Mystery last month where the bottom line was that the sink is a much bigger problem that the source for which many – mostly abiological – candidates exist. One of those may be gone now with the new British study, but the headline here isn't justified at all.

  • Michael Khan

    I fail to see the point you are getting at.

    First of all, you do not mention the dynamics of the methane abundance in the Mars atmosphere. After the initial discovery of that trace gas in 2004, later measurement campaigns, which were independently verified, showed a strong local and seasonal variability.

    The methane concentrations are more accurately described as plumes, forming over limited regions, dispersing with the winds and then decreasing on time4 scales of less than an Earth year, rather than hundreds of years. In his comment, Daniel Fischer posted the link to a blog post of mine where I summarize the findings presented in a recent conference.

    The fact that the methane source and also sink are so dynamic leads to the inevitable conclusion that the yearly release must be orders of magnitude larger than just the 100-300 tons that you would get if you – incorrectly – postulate only photochemical dissociation as the mechanism of methane removal. The currently accepted figures is in the order of up to several tens of thousands of tons per year.

    Even without that British experiment you refer to, I am not aware of anyone who thought that meteorites or comets could account for the methane source. Not only does the sheer amount preclude that – also the seasonal variability is inconsistent with such an explanation. Why should methane-rich objects hit Mars only during Northern Martian spring?

    Then, you mention the mechanism by which methane is produced through a chemical reaction involving volcanic minerals and water. This is the process of serpentinization, which involves the volcanic minerals olivine and pyroxene.

    However, you then state that volcanism is ruled out as a cause. That is true, but it in itself is not exactly news. On Earth too, serpentinization accounts for a significant contribution to the total methane release. On Earth, about 9% of the methane released into the atmosphere are of abiotic origin, the overwhelming majority is associated with life. But on Earth, erupting volcanoes do not constitute an effective mechanism for methane release – most of the geochemically produced methane is released through much less hot mud volcanoes and networks of small vents and cracks. On Mars, such fissures would not be easy to detect from orbit.

    While it is true that life on Mars may account for at least part of the methane source, it is not true that the experiment you describe in any way changes the current approach or theories concerning methane in the Mars atmosphere.

    We just don't know. It is possible to obtain further data on whether methane is of biotic or abiotic origin by analyzing the abundances on certain isotopes, but that will, as some of the scientists you quote stated correctly, imply going there and measuring in-situ.

    So in summary, there already exists a body of knowledge that extends significantly beyond what you report, and frankly, I don't think those issues you raise could be accurately described as "news".

    The issue of methane on Mars certainly is a conundrum. It may be one of the greatest scientific puzzles of our time. But I don't see those experiments you describe as contributing to finding the answer.