Simply put, there is life on Mars – or at least that’s the most plausible explanation that NASA scientists can put forward in order to explain certain observations in the lab. A robotic mission launched thirty years ago, the Viking 1 and Viking 2, brought soil samples back to Earth and these have been thoroughly tested for the presence of Martian life, and the tests have been encouraging.
One of the packages brought back by the Viking spacecraft was collected by the Labeled Release (LR) apparatus. This sample is particularly interesting.
The ticks of life
Soil microbes metabolize and release carbon dioxide, using up minerals in the soil. The carbon in the carbon dioxide contains one radioactive atom in a million million atoms, but since there are lots of carbon atoms around, there is a lot of radioactive carbon as well. And this shows up in any instrument that measures radioactivity, like a Geiger Counter. So the idea is that if a soil sample emits more than its share of radioactive rays, the chances are very high indeed that there are microbes inside, that are churning out carbon dioxide gas, which can escape and be detected. The detector will produce more counts than normal.
They found exactly that! A control sample was put in to confirm that this is indeed due to some source of microbe inside the soil sample. This sample was baked at a high temperature to kill any microbe that might be present. When the two samples were checked for radiation, the unbaked LR sample clocked around 10,000 counts per minute, while the background was only about 100.
However, this is not true of the other two experiments on the Viking spacecraft. This non-confirmation led to the dismissal of the probability of life.
The diurnal cycle of life
Life on any planet, especially if local, adjusts its living patterns – sleeping, hunting etc. – according to the clock on that planet. Lifeforms on Earth have a 24 hour clock schedule, but on Mars the day is 24.7 hours long, and that will be the so-called ‘circadian rhythm’.
The funny thing is that the radiation emitted by the LR apparatus sample also shows this daily cycle. The radiation goes down, indicating a period of inactivity, then goes up again. The oscillation is periodic with the exact period of 24.66 hours.
Joseph Miller, a neurobiologist at University of Southern California, and a member of the study says:
That is basically a circadian rhythm, and we think circadian rhythms are a good signal for life.
No one has yet cultured a Martian microbe. The next spacecraft explorer – Curiosity – which is scheduled to land on Mars in a few days will shed much more light on this very critical issue.
We may not only have company in the Universe, it might even be just next door.
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