From: Stig Agermose <stig.agermose@privat.dk>
Date: Tue, 08 Oct 2002 02:03:40 +0200
Fwd Date: Tue, 08 Oct 2002 07:19:25 -0400
Subject: Boost For Life On Europa


Source: BBC News,

http://news.bbc.co.uk/2/hi/sci/tech/2284852.stm

Stig

***

Monday, 30 September, 2002, 13:52 GMT 14:52 UK

Boost for life on Jupiter moon

By Helen Briggs, BBC News Online science reporter

**

The chances of finding life on other worlds have received a
boost.

Data from the Galileo space probe's journey to Jupiter suggests
an ocean on its moon, Europa, is somewhat Earth-like.

Scientists in the United States think the moon's icy crust is
relatively thin.

There seem to be cracks and vents, which would allow gases, heat
and organic matter to reach what may be water beneath.

Dr Richard Greenberg and colleagues at the University of
Arizona, Tucson, US, came to this conclusion after looking at
images of the moon's cracked surface.

They were captured by the space probe Galileo, which has been
flying past some of Jupiter's many moons over the past few
years.

Dr Greenberg's team thinks the Europan sea has parallels with
some of Earth's icy oceans. Surprisingly, perhaps, it appears to
be more like the Arctic Ocean than Lake Vostok.


Buried bugs


Lake Vostok in Antarctica is one of the deepest-known bodies of
fresh water on the planet.

At least 30 million years old, it is a model for some of the
ice-covered oceans elsewhere in the Solar System.

Some have proposed that the lake might contain previously
undiscovered lifeforms.

But Vostok is now thought to be too isolated from surface
influences to harbour anything more than the most primitive
organisms.

Europa, though, appears more like the Arctic Ocean, the Earth's
smallest ocean, which occupies the region around the North Pole.

The Arctic Ocean is exposed to air and heat by the cracking and
melting of ice.

Europa too seems to have surface-to-ocean connections via
cracks, thermal vents, and tidal displacement, according to the
Arizona team.

Dr Cynan Ellis-Evans, of the British Antarctic Survey, is quick
to see the significance.

"In thermodynamic terms life abhors equilibrium," he says.
"These new interpretations suggest that a Europan ocean and its
ice cap could be dynamically interacting with the moon's surface
atmosphere over short time scales that increase opportunities
for life to exist and evolve."


Seeds of life


One intriguing possibility is that sulphur ejected from
Jupiter's volcanic moon, Io, could make it across to Europa.

"If we're getting a sulphur source going into the lake it's an
exciting possibility," Dr Ellis- Evans adds. "It increases the
opportunity for life".

Astrobiologists had thought the ice sheet covering the moon was
too thick to allow anything to get in. The new research will
give them food for thought.

"It is informed speculation which suggests that the condition
and environment will be suitable for life," says Dr Mark
Burchell, a space scientist at the University of Kent in
Canterbury, UK.

One scenario is that a meteoroid crashing into Europa could have
punched through the ice, carrying the building blocks of life.

"Dust and meteorites carrying organic or volatile materials
could have been delivered to the ocean below the surface," he
says.

The American space agency is seriously considering sending a
robotic probe to Europa to drill through the ice.

The research, published in the US journal Reviews of Geophysics,
will be welcome news for the scientists lobbying Nasa to go.

c. MMII

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