Scientific News  Hypotheses Hypotheses about processes in space WHAT MAKES EUROPA PINK? DOES EUROPA'S ROSY GLOW BETRAY A FLOURISHING COLONY OF BUGS?
WHAT MAKES EUROPA
PINK? DOES EUROPA'S ROSY GLOW BETRAY A FLOURISHING COLONY OF BUGS?
 The red tinge of
Europa, one of Jupiter's moons,
could be caused by frozen bits of bacteria. Their presence would also help
explain Europa's mysterious infrared signal.
Europa is mostly frozen water, but
it absorbs infrared radiation differently to how normal ice does. Researchers
think this is because something is binding the water molecules together.
Salts
of magnesium sulphate frozen within the ice, for example, would make the
molecules vibrate at different frequencies. But no one has managed to come up
with the perfect mix of salts to explain all of Europa's spectrum.
Astrogeophysicist Brad Dalton wondered if
something else was bound up with the water molecules. "Just on a lark, I
asked a colleague of mine at Yellowstone if he had any IR spectra of
extremophile bacteria," he says, and he was shocked by how well they
matched Europa's mysterious spectrum. Then he analysed three kinds of bacteria
under the same sort of conditions as Europa: its temperature is about -170 ¡C
and at 0.01 millibars it has virtually no atmosphere.
Preliminary results show that all three species,
the ordinary gut bacteria Escherichia coli, and extremophiles Deinococcus
radiodurans and Sulfolobus shibatae, are just as good at explaining Europa's IR
spectrum as the salts. However Dalton says the two species that thrive under
extreme conditions are obviously more likely candidates for life on the icy moon.
They also happen to be pink and brown, which would help explain the red patches
on the moon's face.
Bacteria couldn't survive on Europa's surface,
but there might be liquid water inside Europa's icy crust capable of supporting
life. "They could be blasted out to the surface in some kind of eruption
and flash frozen," says Dalton. He plans to present his results at the
Lunar and Planetary Science conference next spring.
Glenn Teeter from the Pacific Northwest National
Laboratory in Washington state says bacteria aren't the simplest explanation for
Europa's spectrum. "It does strike me as a bit far fetched," he says.
But it can't be ruled out until we go there to see.
###
Author: Nicola Jones
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Source of the given news and the copyrights
belong to a New
Scientist
Publishing date: December 11, 2001
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