In 1976 NASA placed two Viking Landers on the surface of Mars.
These have been the only landers sent to the Red Planet that had experiments on board that were specifically designed to find living microbes in the Martian soil.
Two of the three experiments confirmed the existence of life on Mars. The third experiment was designed to find organic molecules in the soil. The life and death of microbes should leave a build-up of these complex chemical building blocks of life in the soil.
No organics were detected and NASA ignored the positive evidence from the other two experiments.
Many years later it was admitted that the organics detector was not sensitive enough to detect any organic molecules that microbes produced.
Also, many years later, further analysis of the apparent metabolic activity from the Martian soil in the other two experiments showed that it followed a diurnal cycle. Even though the soil samples were kept at a constant temperature and lighting, the suspected microbes were metabolising according to the external Martian day/night cycle. In other words, the suspected microbes seemed to be following a "body clock" rythm that made them sleep at night.
NASA scientist Gilbert Levin was in charge of the Viking biology experiments and has always had the opinion that the Viking landers found life on Mars.
The video is a short interview with Levin explaining one of the reasons why he holds this opinion
(This article continues after the video below)
Gilbert Levin has his own website setting out the evidence that the Viking Lander biology experiments found life on Mars. Click the link below to access decades of scientific papers on the matter.
In December 2014 NASA announced that the Curiosity rover operating in Gale Crater had detected the missing organic molecules. However, they were not sure whether the organics were produced by life or by geological chemical processes.
OTHER EVIDENCE FOR LIFE ON THE RED PLANET
In August 1969 Mariner 7 reached Mars and detected some methane and perhaps ammonia in the Martian atmosphere. Methane breaks down fairly quickly in both the atmosphere of the Earth and Mars. This meant that some source had to be constantly replenishing the methane. An obvious possible source - and very important on Earth - is current or past life. (Earth's energy economy is very dependent on methane that is the fossil left-over of ancient decomposed life on Earth. Most methane on Earth - 95% - is the product of current life or past life).
It had long been suggested that one of the tests for life on a newly explored planet is that it changes the composition of that planet's atmosphere. Earth's current Nitrogen-Oxygen atmosphere is the result of the evolution of photosynthetic life...... or plants.
However, within a few weeks the lead investigator - George Pimental - mysteriously retracted the discovery of methane and ammonia on Mars by Mariner 7.
...... But you can't keep life down -
In September 2003 NASA's Centre for Astrobiology, using sensitive instruments at NASA's Infrared Telescope Facility in Hawaii and a similar facility in Chile, announced the detection of methane on Mars. Furthermore they could map the methane emissions to the planet's equatorial regions.
Then in 2004 -
The European Space Agency's (ESA) Mars Express Mars Orbiter was reported to have detected not only methane, but formaldahyde too. Formaldahyde is an even stronger bio-marker for life than methane because it can only survive a few hours in the Mars atmosphere before breaking down. It would therefore have to be continuously produced by some very consistent source - like life.
"Speculation is that already methane is a rather strong indicator life is probably present today on Mars. Just simply based on methane. ...Formaldehyde is destroyed in the Martian atmosphere within 7.5 hours. There is no way that formaldehyde can exist and remain for a long time in the Martian atmosphere. If (formaldehyde) confirmed, possibly life on Mars today, yes." - Vittorio Formisano, Ph.D., Physicist Principal Investigator of the Planetary Fourier Spectrometer for Mars Express.
Another team of astronomers using an Earth based telescope, led by Vladimir Krasnopolsky also detected methane in the Martian atmosphere around the same time. In a published science paper published in August 2004 they discounted volcanic, hydrothermal and fossil sources for the methane and concluded in their abstract that -
"Therefore, methanogenesis by living subterranean organisms is a plausible explanation for this discovery. Our estimates of the biomass and its production using the measured CH4 abundance show that the martian biota may be extremely scarce and Mars may be generally sterile except for some oases."
On Earth such methane belching bacteria are found in the guts of animals, at the bottom of swamps or deep underground and are known as methanogens. They require no oxygen. Underground colonies get by on water, hydrogen in rocks and carbon dioxide, (see µµµ). The interesting thing is that there is another group of Earth bacteria that feed on methane. These methanothrophic/methanotropic bacteria can live in environments both with and without oxygen. They get by on any source of water, methane and formaldehyde - the latter of which usually kills bacteria (see µµµ). Crucially, formaldehyde tends to form easily in the presence of any methane source.
There is therefore scope for there to be a symbiotic ecosystem of methanogenic and methanothrophic bacteria under the Martian surface. The methanogens produce the methane and formaldehyde that the methanothrops require. The methanothrops mop up the methane and formaldehyde that would otherwise poison the methanogens. The efficiency of such a system may be such that very little of the methane produced by the methanogens leaves the ground. There may therefore be much more than a few "oases" of bacterial life on Mars as suggested by Krasnopolsky.
The Reluctance to Announce the Discovery of Life on Mars
Professor Formisano was prevented by ESA officials from officially presenting the results from the Mars Express spacecraft. They stopped him just as he was about to step onto a conference podium to present his paper on the topic. (ESA explained their reticence by explaining that they had decided that there must be something wrong with the detectors on Mars Express).
The abstract from his paper had previously been released and had an extra-ordinary conclusion -
"A symbiosis of methanogenic bacteria with methanothrophic bacteria in the Martian underground can be an alternative interpretation and looks more likely."
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