Discovered in 1956 and mapped in 1990, Lake Vostok is one about of the 375 lakes beneath Antarctica’s ice sheets. It is also the largest body of water in the Antarctic, seventh in the world (by volume) and fourth deepest. Its length is about 250 kilometres, width about 50 kilometres; depth averages 344m, although it can be as much as 800m in places.
The lake lies under an ice cap about 3,700m thick and is thought to have been cut off from the surface for millions of years. A team of Russian scientists drilled through the ice cap in 2012, collecting water samples and analysing the RNA existent in them for the possibility of existence of life forms inside the lake.
About 94% of the samples contained RNA that could be classified as pertaining to bacteria, while 6% of them contained eukaryote RNA (complex, multi-cellular organisms). Many of the RNA sequences closely resembled those of bacteria living inside fish intestines. Since RNA is more unstable than DNA, it is less likely to remain unchanged for millions of years. Therefore, the sequences identified are “likely [were] from living organisms present in the accretion ice.”
A large number of the identified sequences belong to organisms living in proximity to volcanic hydrothermal vents, which would “provide sources of energy and nutrients vital for organisms living in the lake.”
Lakes such as Vostok are of particular interest for astrobiologists, since the extreme conditions found there (such as high pressure, low temperatures and others) might be quite close to those found on moons of the gas giants (Jupiter, Saturn, Uranus, Neptune), such as Europa.
Image Courtesy: motherboard.vice.com