CHICAGO – Where can scientists find clues to help them locate and understand life beyond Earth? According to speakers at the 2015 Astrobiology Science Conference, the hunt begins in many locations, from planets beyond our solar system to the ground beneath our feet.
At a news briefing hosted by NASA, three speakers discussed a wide range of ways that scientists are assisting in the search for life elsewhere in the universe. Those efforts include studies of extreme life-forms on Earth, photographs of the sun glinting off Earth's ocean, and studies in Antarctica that will assist a mission to one of Jupiter's icy moons.
John Grunsfeld, associate administrator for science at NASA, opened the panel discussion with remarks about his own passion and enthusiasm for the search for life, and how it fits into NASA's overall mission to "innovate, explore, discover and inspire." [10 Exoplanets That Could Host Alien Life]
"[We're] quite interested in the capability of rocks to store energy within them to be used to power biological systems," Templeton said. "Essentially, there's a fundamental understanding that rocks have within them, depending on their chemistry, the ability to release electrons or components that can fuel and power different systems essentially much like fuel cells do. And one of the big questions at the moment is how we can couple the energy that's stored within rocks into biological systems."
If rocks can serve as an energy source for life, it might opened up new possibilities for where life could thrive in the universe. In particular, it could mean that organisms don't need direct exposure to sunlight, but could live in subsurface environments.
Templeton said the group is investigating life-forms found in the deserts of Oman, where rocks formed in the Earth's mantle have come to the surface. Prolonged contact between the rocks and pools of water has "changed the water chemistry progressively," Templeton said, making it highly alkaline — a "rare type of water to find on Earth." Life-forms discovered in these pools are not only surviving in the alkali environments, but are optimized for them.
"This is, then, very exciting to start to imagine that there's biological life-forms that may be well adapted in the subsurface environment to be sustained by the reactions between these rocks and water," Templeton said.
Britney Schmidt, an assistant professor of earth and atmospheric sciences at the Georgia Institute of Technology, discussed the search for life in sub-surface oceans such as those found on Jupiter's icy moons and other icy worlds.
"We think a lot about Mars in the search for life in the solar system, but there's a whole host of ice-rich worlds that harbor subsurface oceans," Schmidt said. "And these are important places to think about in the search for life, even within our own solar system."
NASA recently announced a suite of instruments that the agency selected to go aboard a planned satellite mission to Europa, one of Jupiter's moons. Scientists say its possible life could exist beneath the icy surface of Europa, in the immense ocean that lies below.
Currently, Schmidt is principal investigator for the NASA-funded project Sub-Ice Marine and Planetary Analog Ecosystems, or SIMPLE, a project that Schmidt says will assist future missions to icy worlds.
"[We] work with a number of different vehicles, a number of different remote sensing and in-situ sensing platforms, to study our ocean the same way we'd want to study the ocean of [Jupiter's moons] Europa or Enceladus," Schmidt said.
The project includes a vehicle called "Icefin," which is exploring the ocean below the Antarctic ice. Another instrument, called "Artemis," will perform long-range exploration under the ice; another project will conduct ice-penetrating radar studies of the ice shelves of the Antarctic, all of which are "perfect analogs" for the work that is set to be done by radar instruments flying over Europa. [Photos: Europa, Mysterious Icy Moon of Jupiter]
A glimmer of life
Vikki Meadows, a professor of astronomy and principal investigator at the University of Washington's Virtual Planetary Laboratory in Seattle, spoke last about studies that could assist in identifying signs of life through direct observations of exoplanets.
She presented an image taken by the LCROSS satellite (before it crashed into the moon in 2009) of the Earth as a partially illuminated crescent. The curved sliver of light was not uniform — it featured a slightly brighter section right near its midpoint. That, said Meadows, was a glint of sunlight reflecting off the ocean.
This "glint effect," Meadows said, is something that scientists theorized might reveal the presence of an ocean on a distant exoplanet. But the images taken by LCROSS are the first "glint" data ever collected.
"By comparing our models and that data, we were able to confirm that in fact our models are accurate," Meadows said. "We have more confidence now about predicting the type of signals we might be able to detect from extrasolar planets when we go for the gold and actually try to detect an ocean on another planet."
Meadows' team has also done work to help narrow down what kind of elements and molecules in a planet's atmosphere might indicate the presence of life — in particular, what the presence of oxygen says about the presence or absence of life — and how to spot false positives.
"We now are getting a much more mature view of what we should be looking for and what might fool us," Meadows said. "We know in particular which targets we should choose preferentially that will help us avoid these false positives for life and also what other things in the planetary spectrum we should look for that might help us figure out what's going on."
The panel's comments reflected just a sampling of the research being presented at the meeting this week, and a small indication of the work that is slowly but steadily moving the scientific community closer to the possibility of identifying life elsewhere in the universe..
"Are we alone? Is there another civilization out there? Is there any other life out there?" Grunsfeld said in his opening remarks. "The fact that we're here, and the fact that life is so complex on Earth, rocks survive on a tiny bit of chemical energy, to me is convincing that there is a very high probability there's life elsewhere."
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