[meteorite-list] Asteroid found to have water, organics

From: drvann at sas.upenn.edu <drvann_at_meteoritecentral.com>
Date: Thu, 29 Apr 2010 11:16:05 -0400
Message-ID: <1272554165.4bd9a2b5b1410_at_webmail.sas.upenn.edu>

More asteroial mining, perhaps:
A new article in Nature sumarized here:

Organic Molecules Found on Asteroid
April 29, 2010

Scientists have found lots of life-essential water?frozen as ice?-in an
unexpected place in our solar system: an asteroid between Mars and Jupiter.

The discovery of significant asteroid ice has several consequences. It could
help explain where early Earth first got its water. It makes asteroids more
attractive to explore, dovetailing with President Obama's announcement earlier
this month that astronauts should visit an asteroid. And it even muddies the
definition between comets and asteroids, potentially triggering a Pluto-like
scientific spat over what to call these solar system bodies.

This asteroid has an extensive but thin frosty coating. It is likely replenished
by an extensive reservoir of frozen water deep inside rock once thought to be
dry and desolate, scientists report in two studies in Thursday's issue of the
journal Nature.
Two teams of scientists used a NASA telescope in Hawaii to look at an asteroid
called 24 Themis, one of the bigger rocks in the asteroid belt between Mars and
Jupiter. They examined light waves bouncing off the rock and found the distinct
chemical signature of ice, says Univ. of Central Florida astronomy professor
Humberto Campins, lead author of one of the studies.

Astronomers have long theorized that hydrogen and oxygen and bits of water
locked in clay are in asteroids, but this is the first solid evidence. And what
they found on 24 Themis, a rock more than 160 km wide with temperatures around
-70 C, was more than they ever expected. About a third of the rock seemed to be
covered in frost.

Furthermore, scientists didn't just find ice; they found organic molecules,
similar to what may have started life on Earth, Campins says.

"This asteroid holds clues to our past and how the solar system and water on
Earth may have originated and it also has clues to our future with exploration
of near-Earth asteroids," Campins told The Associated Press.

"We're showing that they're wetter than we thought," Campins says. "We're
showing they have organic molecules that might have been the building blocks of
life on Earth."

Earth, when it formed billions of years ago was dry, scientists say. So where
did the water come from? One leading theory is from crashing comets that are
essentially icy snowballs.

But comets come from the outer reaches of the solar system and tend to have more
heavy hydrogen than the water in our oceans, says Donald Yeomans, manager of
NASA's Near Earth Object Program office. Icy asteroids between Mars and Jupiter
might have the right heavy hydrogen ratio to match what's on Earth, says
Yeomans, who wasn't involved in the studies.

MIT's Richard Binzel, also praised the studies, calling the findings "one more
piece in the puzzle for an abundance of water arriving on Earth and having
available the ingredients for life."

Normally, the ice on the asteroid should have escaped Themis as a gas over
thousands of years, but it's still there after a billion years or so, Campins
says. That means there's likely a supply of ice inside the rock, replenishing
the surface, he says.

And if that's the case for other similar asteroids - especially those that come
closer to Earth--then it would be a boon for visiting astronauts, Campins and
others says. The astronauts could use the water to drink and to help make fuel.
The new NASA space plan calls for astronauts to head to a nearby asteroid
sometime in about 15 years as a stepping stone to Mars.

The icy asteroid also just makes a mess of the differences between asteroids and
their cosmic cousin, the comet. The general definition has been that asteroids
are dry rocks and comets icy snowballs.

Now it seems to be more a continuum of dry and icy with not much difference
between asteroids and comets, Campins and others says.

And that, says Andrew Rivkin of Johns Hopkins Univ., co-author of the other
study in Nature, could wind up another cosmic controversy like the debate a few
years ago about whether Pluto was a planet. Pluto wound up demoted and is now
called a dwarf planet.

Source: The Associated Press
Received on Thu 29 Apr 2010 11:16:05 AM PDT