MessageToEagle.com - "Life is far more diverse, and far more resistant to conditions we consider hostile,
than was thought possible only a decade or two ago.
Studying these organisms helps us understand that life may be far more widespread in the cosmos than we
previously imagined," said NASA's astrobiologist Richard Hoover who discovered a new type of life in an Artic tunnel.
The creatures had been frozen for 32,000 years but were still alive. As soon as the ice melted, they began swimming,
eating and were prepared to multiply, and according to Hoover, this type of life might be able to survive in
its suspended state for million for years.
An artistís impression of an exoplanet. Planets could appear blue because they have oceans,
but they could also appear blue for other reasons such as methane abundance like in Neptuneís atmosphere.
Image: NASA/ESA/G Bacon (STScI).
Organisms can live in temperatures of boiling water, in extremely acid or alkaline conditions, in extremely solid salt
and others have no need of water.
Certain creatures require a very high temperature for their survival while others
take pleasure in cold conditions; ten to fifteen degrees below zero suit them just fine.
Such organisms are called extremophiles.
If they exist on Earth, why could they not live elsewhere in the universe or for example in environments of odd exoplanets?
Astronomers have discovered a veritable rogues' gallery of odd exoplanets -- from scorching hot worlds
with molten surfaces to frigid ice balls.
And while the hunt continues for the elusive "blue dot" -- a planet with roughly the same characteristics
as Earth -- new research reveals that life might actually be able to survive on some of the many exoplanetary
oddballs that exist.
"When we're talking about a habitable planet, we're talking about a world where liquid water can exist," said
Stephen Kane, a scientist with the NASA Exoplanet Science Institute at the California Institute of Technology in Pasadena.
"A planet needs to be the right distance from its star -- not too hot and not too cold." Determined by the size
and heat of the star, this temperature range is commonly referred to as the "habitable zone" around a star.
Kane and fellow Exoplanet Science Institute scientist Dawn Gelino have created a resource called the "Habitable
Zone Gallery." It calculates the size and distance of the habitable zone for each exoplanetary system that has been
discovered and shows which exoplanets orbit in this so-called "goldilocks" zone.
The Habitable Zone Gallery can be found at www.hzgallery.org . The study describing the research appears in the
Astrobiology journal and is available at http://arxiv.org/abs/1205.2429.
But not all exoplanets have Earth-like orbits that remain at a fairly constant distance from their stars. One of the
unexpected revelations of planet hunting has been that many planets travel in very oblong, eccentric orbits that vary
greatly in distance from their stars.
Click on image to enlarge
Eccentric Habitable Zones
While Earth and the other planets in our solar system travel around the sun in near-circular
orbits, planets in other systems can have more comet-like orbits in which the distance from the planet to
star varies. Such orbits, termed eccentric, would cause the planet to move in and out of the habitable zone.
A habitable zone, shown in green here, is defined as the region around a star where liquid water, an essential
ingredient for life as we know it, could potentially be present. Earth always remains in its habitable zone.
The hypothetical planet is depicted here moving through the habitable zone and then further out into a long,
cold winter. During this phase of the orbit, any liquid water on the planet will freeze at the surface; however,
the possibility remains that life could, in theory, hibernate beneath the surface. Image credit: NASA/JPL-Caltech
"Planets like these may spend some, but not all of their time in the habitable zone," Kane said.
"You might have a world that heats up for brief periods in between long, cold winters, or you might have brief spikes
of very hot conditions."
Though planets like these would be very different from Earth, this might not preclude them from being able to
support alien life. "Scientists have found microscopic life forms on Earth that can survive all kinds of
extreme conditions," Kane said.
"Some organisms can basically drop their metabolism to zero to survive very long-lasting, cold conditions.
We know that others can withstand very extreme heat conditions if they have a protective layer of rock or water.
There have even been studies performed on Earth-based spores, bacteria and lichens, which show they can survive
in both harsh environments on Earth and the extreme conditions of space."
Kane and Gelino's research suggests that habitable zone around stars might be larger than once thought, and that
planets that might be hostile to human life might be the perfect place for extremophiles, like lichens and bacteria,
"Life evolved on Earth at a very early stage in the planet's development, under conditions much harsher
than they are today," Kane said.
Kane explained that many life-harboring worlds might not be planets at all, but rather moons of larger,
gas-giant planets like Jupiter in our own solar system.
"There are lots of giant planets out there, and all of them may have moons, if they are like the giant
planets in the solar system," Kane says.
"A moon of a planet that is in or spends time in a habitable zone can be habitable itself."
As an example, Kane mentioned Titan, the largest moon of Saturn, which, despite its thick atmosphere, is
far too distant from the sun and too cold for life as we know it to exist on its surface.
"If you moved Titan closer in to the sun, it would have lots of water vapor and very favorable conditions for life."
Kane is quick to point out that there are limits to what scientists can presently determine about habitability on
already-discovered exoplanets. "It's difficult to really know about a planet when you don't have any knowledge about
its atmosphere," he said. For example, both Earth and Venus experience an atmospheric "greenhouse effect" -- but
the runaway effect on Venus makes it the hottest place in the solar system.
"Without analogues in our own solar system, it's difficult to know precisely what a habitable moon or eccentric
planet orbit would look like."
Still, the research suggests that habitability might exist in many forms in the galaxy -- not just on planets
that look like our own.
"There are lots of eccentric and gas giant planet discoveries," Kane says. "We may find some surprises out
there as we start to determine exactly what we consider habitable."
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Is it possible to change the outcome of this virtual game?
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