[meteorite-list] ISO Finding Questions Theory That Liquid Water Was Present In Young Solar System

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 09:55:47 2004
Message-ID: <200201162018.MAA11304_at_zagami.jpl.nasa.gov>

ESA Science News Release

EMBARGOED until 16 January 2002 20:00 CET (14:00 EST)

ISO finding questions accepted theory that liquid water was present
in young Solar System

Planet-like bodies with liquid water formed very early in the history
of the Solar System, or so scientists used to think. That scenario
may now be due for revision after a finding with ESA's Infrared Space
Observatory, ISO. The theory was based on the presence of certain
minerals called carbonates in primitive Solar System objects. Carbonates
are thought to form in liquid water, which can only exist in large,
planet-like bodies. Using ISO, an international team has discovered
large amounts of carbonates around two dying stars, where large bodies
do not exist. This suggests that carbonates are not necessarily linked
to liquid water. This is the first detection of carbonates outside the
Solar System.

"Our finding suggests that not all carbonates found in the Solar System
were formed in association with liquid water, and this of course sheds
new light on the formation history of the Solar System," says Ciska
Kemper, of the University of Amsterdam.

The Solar System formed out of residual material left-over from the
formation of the Sun itself. About 5 000 million years ago 'clumps' in
this material -which was swirling around the newborn Sun - began to grow,
and some ended up forming the planets. Nowadays astronomers can study the
earliest stages of the process by analysing Solar System objects that are
known to be very primitive, such as certain meteorites. For instance, in
several of these objects they have found very old carbonates. This is
considered to be evidence that large, planet-like bodies with liquid water
had 'formed' already 20 million years after the formation of the first
clumps of material around the Sun.

Liquid water is thought to be a key ingredient for the formation of
carbonates. On Earth, a large fraction of sedimentary rocks are carbonates -
for instance, limestone and marble. They are the sediments that precipitate
when a watery solution of carbon dioxide and another mineral, such as calcium,
becomes saturated - the 'scale' in the tea kettle forms in the same way.
Carbonates exist also in grains of dust between the planets, in asteroids
and in meteorites coming from Mars, for example, in the famous meteorite
ALH 84001, which some say contains fossilised bacteria.

However, ISO's discovery, for the first time, of carbonates in dying stars
breaks the automatic association between these minerals and liquid water.
Kemper and her colleagues have found large amounts of the carbonates calcite
and dolomite in the nebulae NGC 6302 and NGC 6537, dubbed respectively the
'Bug Nebula' and the 'Red Spider Nebula'. These are old stars that have
spent the last ten thousand years expelling material through dense stellar
winds and are about to 'die' as white dwarfs - small, very dense and opaque
'corpses' of stars. It is in the expelled material, which now forms a shell
around the central star, where ISO has identified the unmistakable chemical
signature of the carbonates, their spectra. And these carbonates cannot have
been formed through the interaction with liquid water: neither has the
material from the stars condensed to form new planets, nor are the
carbonates residual from a pre-existing planetary system destroyed by the
dying star.

"The amount of carbonates we find is equivalent to at least 30 Earth masses,
far too large to be the relic of a hypothetical planetary system present
before the star became a planetary nebula. On the other hand, the age of the
dust-shell in the nebula is about ten thousand years, which is too short for
a new planetary system to form," explains Kemper.

Therefore, the carbonates around the Bug Nebula and the Red Spider Nebula
must have formed through an alternative mechanism that does not involve
liquid water. Kemper and colleagues suggest several possibilities but
say none of them has been tested in the laboratory yet.

Was this alternative mechanism also at work in the early Solar System?
The authors cannot say. But the mere possibility implies that the
assumption that carbonates in primitive Solar System objects indicates the
quick formation of planets with liquid water in the Solar System needs to
be reviewed.

For more information please contact:

Science Programme Communication Service, ESA
ESTEC- Noordwijk, The Netherlands
phone: + 31(0)71.565.32.73
fax: + 31(0)71.565.41.01

Scientific contact
Dr. Leo Metcalfe - ISO Project Scientist
ISO Data Centre - Madrid, Spain
phone: +34(0)91.81.31.372
fax: +34(0)91.81.31.308

About ISO
The European Space Agency's infrared space telescope, ISO, operated
from November 1995 until May 1998, almost a year longer than expected.
As an unprecented observatory for infrared astronomy, able to examine
cool and hidden places in the Universe, ISO successfully made nearly
30 000 scientific observations. More information about ISO can be

found at http://sci.esa.int/iso .

Images for this News Release are available at

http://sci2.esa.int/press/20020117ISOwater/.

These ISO results will be published in the 17 January 2002 issue of
the scientific journal Nature.
Received on Wed 16 Jan 2002 03:18:12 PM PST