Extremophile Hunt Begins in Antarctica, Implications for Exobiologists

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An expedition has set off for Antarctica’s Lake Untersee in the quest to find bacteria living in one of the most extreme environments on Earth. The bacteria-hunting team are looking for a basic lifeform in a highly toxic location. Resembling the chemistry of Mars, moons of Jupiter and Saturn, even comets, the ice-covered lake may hold some clues to how life might survive, thrive even, beyond the “normality” of our planet.

Lake Untersee is a strange place. For starters, it is always covered in ice. Secondly, the water’s pH level is so alkali that it resembles bleach rather than regular lake water. And third, it produces methane on a scale that dwarfs any other source on Earth. In fact, the chemistry of this terrestrial location has been likened to the high alkalinity, high methane environments on Mars, frozen moons and comets in our solar system neighborhood.

We already know that extreme life can thrive in the superheated conditions along volcanic vents in the oceans and they can live quite happily in nuclear reactors. Some bacteria are content to be frozen for over 30,000 years before they are thawed to continue life as if nothing had happened. So the search continues… can life thrive in conditions where the pH (a measure of a substances acidity or alkalinity) is considered to be toxic to life? The head scientist of the Antarctic team, Richard Hoover of NASA’s Marshall Space Flight Center, believes that although we consider life that we know to thrive in the “normal” conditions we know and experience ourselves, this may not be the “norm” for life elsewhere in the cosmos.

One thing we’ve learned in recent years, is that you don’t have to have a ‘Goldilocks’ zone with perfect temperature, a certain pH level, and so forth, for life to thrive.” – Richard Hoover.

The team of US, Russian and Austrian scientists hope to identify additional extreme bacteria to add to their impressive accolade of discoveries. So far, previous teams headed by Hoover have found new species and genera of anaerobic microbial extremophiles in the ice and permafrost of Alaska, Siberia, Patagonia, and Antarctica. Now they hope to find life that is hardy enough to deal not only with the extreme cold of the Antarctic, but also with the “normally” poisonous pH and high methane in Lake Untersee. This will characterize the signature of extreme life, a great help to exobiologists when results come in from future life-hunting missions to Mars and other planetary bodies.

With our research this year, we hope to identify some new limits for life in terms of temperature and pH levels. This will help us decide where to search for life on other planets and how to recognize alien life if we actually find it.” – Hoover.

Source: Physorg.com

Earth, Barely Habitable?

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Our home planet has been often described in glowing, nurturing terms. A cradle for life, right in the goldilocks zone. But our planet is actually right on the edge of habitability. If it were any smaller, and a little less massive, plate tectonics might never have gotten started. It turns out, life needs plate tectonics.

Astronomers at the Harvard-Smithsonian Center for Astrophysics announced their research today at the Winter meeting of the American Astronomical Society. According to the team, plate tectonics only really get going when a planet gathers enough mass. And the Earth has just barely enough mass to enjoy plate tectonics.

“Plate tectonics are essential to life as we know it,” said Diana Valencia of Harvard University. “Our calculations show that bigger is better when it comes to the habitability of rocky planets.”

When a planet reaches a large enough size, huge chunks of the planet’s surface can float atop an ocean of boiling magma. These plates spread apart and crash into one another, lifting up gigantic mountain ranges like the Himalayas.

And without plate tectonics, we wouldn’t be here. The process enables complex chemistry and recycles carbon dioxide, which acts like a blanket to keep the Earth warm and hospitable for life. Carbon dioxide is locked into rocks, and then returned to the atmosphere when the rocks melt. Without this cycle, carbon dioxide would get locked away in rocks forever.

The researchers examined what would happen on different rocky planets. They looked at a range of planets, smaller than our planet, up to the so-called “super-Earths” – planets twice our size with 10 times the mass. Any bigger than that, and you start to get a gas planet.

According to their calculations, the Earth is barely habitable. If you get a planet with more mass, the plate tectonics really get rolling, and the carbon cycle becomes really active. A super-Earth could have globe-spanning rings of fire, bursting with hot springs and geysers. Life would have every opportunity to get started.

Of course, if we tried to visit a super-Earth, we’d find the gravity uncomfortable. We’d experience 3 times the gravity trying to walk around on the surface of the planet. Oh, my back.

But for native life forms, it would be paradise.

Original Source: CfA News Release

Sulphur Spring Harbours Extreme Bacteria

A team of scientists has set out to visit an unusual hot spring on Ellesmere Island near the North Pole. This spring spews out sulphur-rich water that has become an ecosystem for bacteria in an otherwise lifeless ice field. The researchers are hoping to understand the underground structure of the spring, and locate the source of the sulphur. An environment like this could help scientists search for signs of life in other hotspots in the Solar System, such as Mars, Europa, or Enceladus.
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Ancient Life Survived Snowball Earth

Approximately 2.3 billion years ago, bacterial life had generated enough oxygen to make the air breathable for larger creatures. Unfortunately, this was also a stage when our planet went through one of its “Snowball Earth” phases, when the entire planet was encased in kilometer-thick snow and ice. Scientists have found evidence that multi-celled eukaryotes – our distant ancestors – were thriving on Earth, before and after the big chill. While most of the planet was covered, there were probably pockets that were ice free, where islands of life could survive.
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