Do microbes live elsewhere in our solar system?
Signs point to yes….
The Atacama Desert in Chile is one of the most arid and uninhabitable places on earth. Decades can pass without any rainfall. Yet researchers have managed to find life there: microbes. This discovery has inspired hope that there may perhaps be life on Mars.
The international research team found a number of bacteria in the bone-dry soil. Contrary to other species of bacteria, though, these single-celled organisms seemed to be inactive. For quite some time, they were assumed to be dead or perhaps dying bacteria that had been carried there by the wind from other places. However, subsequent research showed that they are specialised bacteria that survive in a form of deep sleep when there is a lack of water. When it rains, they awaken and begin to divide actively.
Chance of rain: 1 in a 1,000
When the researchers first arrived at the desert in 2015, something unusual happened. It began to rain. This exceptional occurrence led to an explosion of biological activity. Using sterile spoons and surgical precision, soil samples were taken at various depths. Near the surface, Geodermatophilaceae and Rubrobacter bacteria were found with a resistance to dehydration and UV radiation. At deeper levels, where saline levels were higher, so-called halophile (‘salt-loving’) microbes such as Betaproteobacteria were encountered.
Researchers think that these micro-organisms may well be able to sleep for hundreds or even thousands of years. The conditions closely resemble the planet Mars. Although conditions there are currently arid and cold, this situation was not always the case. Billions of years ago, Mars had small oceans and lakes that may have hosted early life forms. These life forms perhaps adapted themselves to current conditions on Mars.
Frozen lakes are known to exist on Mars, while recent research suggests that there may even be snowfall. This fact means that circumstances exist in which humidity on Mars could increase. As the research in the Atacama Desert has shown, moisture could revive the microbes. To this end, the team would like to conduct research in Don Juan Pond on Antarctica. Since the shallow lake has a salinity of 40%, it does not even freeze over at −50°C.
Saturn’s icy moon
Mars is not the only place in our solar system where life could exist. There are any number of places where moisture can be found. Austrian and German researchers have used laboratory experiments to show that there could be microbes living on Saturn’s icy moon Enceladus. Cassini, the American spacecraft which explored the planets, showed that there were geysers spewing methane into the atmosphere from a subterranean ocean. According to the researchers, this methane gas possibly is being produced by micro-organisms. They mimicked the circumstances in this ocean within the laboratory. The methane-producing archaea Methanothermococcus okinawensis, found on earth in extremely hot water near deep-sea hydrothermal vents, would easily be able to live in these circumstances.
Source: PNAS and Nature