From the depths to the cosmos

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4A_scienceStudying the most extreme environments on earth may give us clues about what forms of life could potentially exist on other planets

Gizmos & Gadgets
Regan Meloche

Contributor

If you were asked to describe Antarctica in three words today, you might go with cold, ice, and penguins. If you were asked the same question over 100 million years ago, the surprising answer may be something more like warm, forests, and dinosaurs.

The warm climate of Antarctica was present at a time when the region was part of the supercontinent known as Gondwana, which also comprised of Africa, Australia, South America, and the Indian subcontinent.

Many millions of years and geological processeses later, Antarctica became the ice sheet that we know it as today.

While the continent doesn't have any permanent residents, it does have many research stations with scientists from all over the world doing different types of fieldwork.

Presently, a hotspot in the region is Lake Vostok, where Russian scientists may be on the verge of making some important discoveries.

At 16,000 square kilometres, Lake Vostok is the world’s largest known subglacial lake – a body of water covered by a thick layer of ice. Last year, the research team managed to drill through all 4 km of this ice layer, and just last month, they retrieved the first sample of lake water.

Two questions immediately come up.

First, what is liquid water – which shouldn't exist below 0 degrees Celsius – doing on Antarctica, underneath 4 kilometers of ice? A region with the coldest recorded temperature on the entire earth, a recorded chilling -89 degrees Celsius, and yet the liquid form of water exists?

Second, why would anyone be interested in getting at this water?

The liquid water is able to exist for two main reasons.

The centre of the earth is very hot, and as one gets closer to the core, the temperature gets higher. This heat is a combination of heat left over from when the earth first formed, combined with radioactive decay. The heat can be harnessed and used as geothermal energy, helping to keep subglacial lakes from freezing.

The lakes are under a lot of pressure from a dense sheet of ice sitting on top, which can also act as insulators. Water is one of the few substances that expands when going from liquid to solid, which causes the increase in pressure to lower the melting point, allowing the lake to remain in liquid form, at a temperature of about -3 degrees Celsius, the average temperature of Lake Vostok.

But, why are scientists interested in studying this?

Remember the life that thrived on Antarctica before it became a freezing desert? Scientists have been curiously looking for forms of microbial life that may still exist underneath all the ice.

The implications make for some very exciting research.

Lake Vostok has been isolated from the rest of the environment for what some scientists think could be millions of years. This could give us an idea of how organisms have evolved in such situations, and we may be able to learn more about early forms of life.

There are many obstacles that any species in Lake Vostok would have to overcome for life to exist: It's cold, there is no sunlight, very few nutrients, and the water is also heavily saturated with oxygen and nitrogen. Any life that exists here may be similar to life that exists in other extreme conditions, namely in lakes found on some moons in outer space. Finding life in Lake Vostok could give scientists hints as to what might be happening in lakes across the galaxy.

Nothing new has been discovered yet, but samples from the lake will not be seriously analyzed until later this year.

Recently, researchers thought they had been on the brink of discovery of an 'unidentified' and 'unclassified' species, but it was later revealed to be a contaminant from the sampling process.

Although nothing has been found yet, there is good reason to be hopeful.     

American scientists are doing similar research at Lake Whillans, a smaller Antarctic subglacial lake sitting beneath 800 metres of ice. About one month ago, they announced the discovery of microbial life in the lake. According to the research team, it "marks the first successful retrieval of clean whole samples from an Antarctic subglacial lake."

Even more exciting, scientists say, is that similar to animals living in the deeper parts of the oceans, this bacteria is able to exist without photosynthesis, gaining their energy from some other unknown source. According to an article in Scientific American, this source could be existing organic material, or could be due to chemical reactions between the minerals in the bedrock, and in the water.

So what happens if we do find more life in these extreme environments?

The two main candidates for extraterrestrial bodies in the Solar System that contain water are Jupiter's moon Europa, and Saturn's moon Enceladus. Europa is slightly smaller than our own moon, and has an atmosphere consisting mostly of oxygen. With an average surface temperature of -170 degrees Celsius, Europa’s temperature is well below anything we have on earth, but scientists believe that water may exist underneath its icy surface.

Interestingly enough, liquid water may exist for different reasons than radioactive decay and geothermal heat, like on earth. As Europa orbits Jupiter, its distance to Jupiter varies. This causes an effect known as tidal heating, where the moon gets deformed. This constant deformation creates friction, heating up the interior. A similar process can be used to explain heat in Saturn's Enceladus. While astronomers have not explored these moons for some time, the European Space Agency is planning to send a probe to explore Europa in 2022.

Although it's wishful thinking, consider the situation where we find microbes on these moons similar to what we have here on earth. This could imply that life on our planet and life on other planets have a similar origin. This has given rise to the idea of panspermia (literally, sperm everywhere), which says that life exists throughout the universe, possibly being carried by asteroids. So we may have one day been tiny bacteria flying on an asteroid that happened to smash into a younger earth, and found some way to adapt.

Photo courtesy of wired.com and sciencemag.org

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