MARSBUGS:  
The Electronic Exobiology Newsletter
Volume 5, Number 5, 6 March, 1998.

Editors:

David Thomas, Department of Biological Sciences, University of 
Idaho, Moscow, ID, 83844-3051, USA, thoma457@uidaho.edu or 
Marsbugs@aol.com.

Julian Hiscox, Division of Molecular Biology, IAH Compton 
Laboratory, Berkshire, RG20 7NN, UK.  Julian.Hiscox@bbsrc.ac.uk or 
Marsbug@msn.com

MARSBUGS is published on a weekly to quarterly basis as warranted 
by the number of articles and announcements.  Copyright of this 
compilation exists with the editors, except for specific articles, 
in which instance copyright exists with the author/authors.  E-
mail subscriptions are free, and may be obtained by contacting 
either of the editors.  Contributions are welcome, and should be 
submitted to either of the two editors.  Contributions should 
include a short biographical statement about the author(s) along 
with the author(s)' correspondence address.  Subscribers are 
advised to make appropriate inquiries before joining societies, 
ordering goods etc.  Back issues may be obtained via anonymous FTP 
at:  ftp.uidaho.edu/pub/mmbb/marsbugs.

The purpose of this newsletter is to provide a channel of 
information for scientists, educators and other persons interested 
in exobiology and related fields.  This newsletter is not intended 
to replace peer-reviewed journals, but to supplement them.  We, 
the editors, envision MARSBUGS as a medium in which people can 
informally present ideas for investigation, questions about 
exobiology, and announcements of upcoming events.

Exobiology is still a relatively young field, and new ideas may 
come out of the most unexpected places.  Subjects may include, but 
are not limited to:  exobiology proper (life on other planets), 
the search for extraterrestrial intelligence (SETI), ecopoeisis/ 
terraformation, Earth from space, planetary biology, primordial 
evolution, space physiology, biological life support systems, and 
human habitation of space and other planets.
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INDEX

1)	NAKHLA MARS METEORITE AVAILABLE FOR SCIENTIFIC STUDY 
by Monica Grady

2)	CLUES TO POSSIBLE LIFE ON EUROPA MAY LIE BURIED IN ANTARCTIC 
ICE
by Dave Dooling

3)	PALEOCLIMATOLOGY--DECIPHERING MYSTERIES OF PAST CLIMATE FROM 
ANTARCTIC ICE CORES
from the American Geophysical Union

4)	CASSINI MISSION STATUS
JPL release

5)	STARDUST STATUS REPORT
by Ken Atkins
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NAKHLA MARS METEORITE AVAILABLE FOR SCIENTIFIC STUDY 
by Monica Grady

4 March, 1998

Nakhla is a 1300 million year old Martian meteorite, the first one 
in which carbonates were identified.  Nakhla fell as a shower of 
stones in 1911; several of the stones are in the collection of the 
Natural History Museum in London.  One completely fusion-crusted 
stone has been kept unbroken since its acquisition in 1913.

The Natural History Museum is now prepared to offer samples of 
this stone to scientists for appropriate analyses.  The Antarctic 
Meteorite Processing Group had kindly agreed to allow the stone to 
be broken and sub-divided at the Curatorial Facility at the 
Johnson Space Center in Houston, prior to the LPSC in March.

There is no formal deadline for sample requests, but the material 
available is limited.  Coordinated approaches from groups of 
scientists undertaking complementary studies are encouraged.  
Those requests submitted to the Museum by April 3 will be 
processed in April.  Those arriving later will be delayed for 
several months.

For further details and to submit requests, contact:
Dr. Monica M. Grady
Department of Mineralogy
The Natural History Museum
Cromwell Road
London SW7 5BD
E-Mail:  mmg@nhm.ac.uk
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CLUES TO POSSIBLE LIFE ON EUROPA MAY LIE BURIED IN ANTARCTIC ICE
by Dave Dooling

5 March, 1998

More than a century ago, science fiction pioneer Jules Verne wrote 
about people swept "Off on a Comet" and into space where they 
lived more or less happily ever after.  Verne's 1877 book (also 
published as "Hector Servadac") was a bit fanciful, but it had an 
element of truth:  life may have hitchhiked across the solar 
system.  The proof may be found at the ends of the Earth.  This 
week, American and Russian scientists are examining deep ice from 
the Antarctic and hoping to find clues that fungi, bacteria, and 
even diatoms could survive conditions in icy solar system bodies.  
This would help make the South Pole one of the first destinations 
for the growing field of astrobiology.

"It's possible to say that ancient impacts of asteroids on the 
Earth could have ejected soil, rocks, and seawater containing 
terrestrial microorganisms into space, and that they may have made 
it to other places in the solar system," explained Richard Hoover 
at NASA's Marshall Space Flight Center.  Hoover is an X-ray 
astronomer who is also is internationally known for his work on 
diatoms and a firm believer that living microorganisms locked in 
ice have a chance of remaining viable for long periods in outer 
space.

The debate over whether the Antarctic Allan Hills meteorites 
brought life from Mars (or were contaminated by life on Earth) is 
the best known case.  Hoover said that other evidence abounds, 
including asteroids striking the Earth or Mars and blasting 
materials into space, the survival of streptococcus bacteria on 
the Surveyor 3 moon lander, and the survival of microorganisms 
inside Antarctic ice.

The possibilities expanded this week when NASA released new images 
and data that Europa, one of Jupiter's larger moons, slush and 
perhaps liquid water near the surface.  That raises the intriguing 
possibility that Europa may harbor life.

Discoveries on the Earth over the last few years show that life 
thrives or can be preserved in a range of "hostile" conditions, 
from volcanic vents deep in ocean trenches, to ice more than 
400,000 years old, to Siberian permafrost more than 5 million 
years old.

This week, Hoover and Dr. S. S. Abyzov of Russia's Institute of 
Microbiology of the Russian Academy of Sciences in Moscow are 
examining ancient ice drilled at Russia's Vostok (East) Station 
about 1,000 km (1,600 mi) from the South Pole.  Eventually, they 
hope to examine water taken from inside a lake--liquid, not ice--
discovered under Vostok Station in 1996.

The first samples being examined are from 386 meters (1,266 ft) 
down; the deepest in this set is from 1,249 meters (4,097 ft).  
Samples from as deep as 3,610 meters (11,840 ft) are on their way 
from Vostok to the Institute of Microbiology.  Abyzov says that 
portions will be brought to Marshall [Spaceflight Center] later 
this year.

Russian scientists have been drilling at Vostok since 1974.  In 
1996, seismic and other tools revealed the lake's presence in 
1996.  Lake Vostok is overlaid by about 3,710 meters (12,169 ft) 
of ice and may be 500,000 to 1 million years old.  Since the 
discovery, drilling has gone slowly while procedures are worked 
out to keep it pristine.  No one has seen or sampled the lake-- 
the deepest ice sample is from 100 meters (328 feet) above the 
liquid surface--nor is anyone sure why it is liquid, hence the 
scientific curiosity. 

While Lake Vostok holds clues about life on Earth, it also is a 
good model for conditions on Europa.  The lake is about 48 by 
224 km (30 by 140 mi) in size--about the size of Lake Ontario--
and 484 meters (1,600 ft) deep.  Recent data indicate that it has 
about 50 meters (165 ft) of sediment at the bottom.

"Recent research [shows] that extremely severe conditions of 
cosmic environments do not exclude the possibility that 
microorganisms may exist in anabiotic states at high altitudes in 
interplanetary space," Abyzov wrote in a recent paper.  The only 
way to resolve the question is to use the Antarctic as a model for 
conditions in comets, the Martian ice caps, and other icy moons 
orbiting Jupiter and Saturn.

At Vostok station in 1975, Abyzov discovered bacteria, fungi, 
diatoms, and other microorganisms which were blown to Antarctica 
by winds from lower latitudes.  The numbers of the organisms at 
different depths, and thus different ages of the ice, change with 
major climate changes on the Earth.  Thus, the ice also serves as 
a time capsule, preserving specimens of life as far back as 
500,000 years.  This offers the potential for studying how genetic 
material changes over the centuries.

Abyzov brought his samples to Marshall to use the Environmental 
Scanning Electron Microscope, or ESEM, a relatively new tool that 
Marshall uses to analyze how materials fail and break.  It was 
originally designed to analyze biological specimens in their 
natural environment, without coating them in gold to make them 
reflective.  And that's ideal for observing whatever is in the 
ice.  It also uses an X-ray scan to analyze the elements in a 
target, an important step in determining whether an object is 
organic.

The ice specimens will be analyzed at Marshall over the next week, 
then Abyzov will go to the Jet Propulsion Laboratory to work with 
another colleague with different analytical tools.  Check back in 
a few days for a follow-up story on what the ESEM finds.

Abyzov describes his research in a chapter of Antarctic 
Microbiology (E. Imre Friedmann, ed., ISBN 0-471-50776-8, New 
York, Wiley, 1993, 644 pp).  In the book, international 
authorities present expert and comprehensive papers concerning the 
diversity of such Antarctic microorganisms as prokaryotes, fungi, 
algae and protozoa and their freshwater, marine and terrestrial 
environments.  In fact, the entire ecosystem of the Antarctic 
continent and its surrounding seas is based primarily on 
microorganis's.  Coverage ranges from marine sediments and sea ice 
to exobiological implications and environmental concerns.

[More information and images concerning Vostok station may be 
found at http://science.msfc.nasa.gov/newhome/headlines/ 
ast04mar98_1.htm#anchor647575]
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PALEOCLIMATOLOGY--DECIPHERING MYSTERIES OF PAST CLIMATE FROM 
ANTARCTIC ICE CORES
from the American Geophysical Union

[Earth in Space, Vol. 8, No. 3, November 1995, p. 9.  (c)1995 
American Geophysical Union.  Permission is hereby granted to 
journalists to use this material so long as credit is given, and 
to teachers to use this material in classrooms.]

The history of the world's climate is recorded in the layers of 
sediment that accumulated over thousands of years in ice and rock.  
Paleoclimatologists are studying sediment encapsulated in deep 
Antarctic ice to answer a few perplexing questions about the 
conditions that prevailed during the ice ages.

by Vostok Project Members:
S. S. Abysov, M. Angelis, N. I. Barkov, J. M. Barnola, M. Bender, 
J. Chappellaz, V. K. Chistiakov, P. Duval, C. Genthon, J. Jouzel, 
V. M. Kotlyakov, B. B. Kudriashov, V. Y. Lipenkov, M. Legrand, C. 
Lorius, B. Malaize, P. Martinerie, V. I. Nikolayev, J. R. Petit, 
D. Raynaud, G. Raisbeck, C. Ritz, A. N. Salamatin, E. Saltzman, T. 
Sowers, M. Stievenard, R. N. Vostretsov, M. Wahlen, C. Waelbroeck, 
F. Yiou, P. Yiou

Ice cores drilled at Vostok Station, Antarctica, 10 years ago by 
Russia, France, and the United States are providing a wealth of 
information about past climate and environmental changes over more 
than a full glacial-interglacial cycle.  The ice cores show that 
East Antarctica was colder and drier during glacial periods than 
during the Holocene and that atmospheric circulation was more 
vigorous during glacial times.  The ice cores also support 
evidence from studies that use deep-sea sediment to reconstruct 
changes in past sea level and oceanic temperature.  These studies 
link Pleistocene climate change with the position of the Earth on 
its orbit and tie carbon dioxide and methane concentrations to 
temperature.

Vostok research station has operated year-round for more than 37 
years.  In the 1970's, researchers from the Soviet Union drilled a 
set of holes 500-952 m deep in the ice.  These holes have been 
used to study the oxygen isotope composition of the ice, which 
showed that ice of the last glacial period was present below about 
400 m depth.  Then three more holes were drilled:  in 1984, Hole 
3G reached a final depth of 2202 m; in 1990, Hole 4G reached a 
final depth of 2546; and in 1993 Hole 5G reached a depth of 2755 
m.  The station was temporarily closed in January 1994, but it 
reopened last November and drilling continued during the winter of 
1995.  The core, the longest ever drilled, has now reached 3100 m.  
It is 50 m longer than the core from Greenland that previously 
held the record.

Ice cores provide continuous information on key properties of 
paleoclimate including local temperature and precipitation rate, 
humidity, and wind speed.  Ice cores also record changes in 
atmospheric composition.  They can be used to measure trace gas 
concentrations, chemical impurities of terrestrial and marine 
origin, other trace compounds or isotopes, cosmogenic isotopes, 
extraterrestrial material, and aerosols of volcanic and 
anthropogenic origin.  Ice cores from Vostok, Antarctica, were the 
first to cover a full glacial-interglacial cycle.  And, despite 
recent drillings in central Greenland, they still carry the 
distinction of being the only ice cores that scientists are 
certain have remained undisturbed for the last interglacial and 
the penultimate glacial periods.

Interpreting Paleoclimate From Ice Cores

Two elements--deuterium and oxygen 18--are important because they 
can be used to reconstruct past temperature changes in polar 
regions.  In Antarctica, a cooling of 1C results in a decrease of 
9 per mil deuterium.  An accurate chronology is essential for 
interpreting ice core paleoclimate data.  At Vostok, accumulation 
is too low for recognizable annual signals to form, so we 
developed a chronology combining an ice flow model and an 
accumulation model that accounts for the fact that accumulation 
was lower during colder periods and vice versa.

Because the accumulation rate is governed by saturation water 
vapor pressure, past accumulation may be estimated from the 
temperature record.  Accumulation rates inferred in this way are 
supported by measurements of beryllium 10 (10Be), an isotope 
produced by the interaction of cosmic rays and the upper 
atmosphere, can be used to determine past snow accumulation in 
Vostok ice.  Deposition of this cosmogenic isotope is assumed to 
be constant.  The chronology of the ice at Vostok has been 
established down to 2546 m, which is dated at 220,000 years before 
present.  The combined deuterium record from the 3G and 4G cores 
shows the last two glacial-interglacial transitions with 
atmospheric temperature changes of about 6C.  The last ice age is 
characterized by three minima separated by slightly warmer 
episodes called interstadials.  The penultimate glacial is 
characterized by the same sequence of interstadial events and 
taken as a whole the last two glacial periods appear very similar.

The chronology of the Vostok ice core is also supported by a 
glaciological model.  Southern Ocean temperature variations 
correlate with those at Vostok.  Also, because photosynthesis 
transmits seawater variations to atmospheric O2, the variations in 
18O of O2 in air trapped in the Vostok ice roughly coincide with 
variations in 18O of seawater reflected in the isotopic content of 
the forams in deep-sea sediments.  There is also a correlation 
between the Vostok dust concentration and the record of mass 
accumulation rate in a core taken from the Indian Ocean.

Beyond their use as dating tools, ice cores convey specific 
geochemical information.  Variations in 10Be concentrations are 
caused by factors other than accumulation changes.  The existence 
of peaks in 10Be around 35 and 60 kyr B.P. have been attributed to 
increased production of 10Be.  The 18O of O2 record also contains 
information about fractionation by biogeochemical and hydrologic 
processes.  Similarities between Vostok and Southern Ocean 
temperatures indicate that the Vostok record is representative of 
a large geographical area, while agreement with the 18O of deep-
sea core suggests that the broad features of this record are 
somewhat global.

Changes in terrestrial aerosols hold the key to past climate.  
More dust was present in glacial periods than during 
interglacials; this suggests that glacial periods were 
characterized by extensive deserts, intense surface winds in the 
desert source regions, and more efficient transport along the 
imaginary circular path that runs perpendicular to the equator 
through the poles.  This idea of stronger circulation during 
glacial periods is reinforced by the fact that glacial values of 
marine aerosols are much higher than interglacial levels.

Another important aspect of change in the past atmosphere's 
aerosol load is a secondary aerosol composed of nonseasalt sulfate 
and methanesulfonic acid (MSA), an oxidation product emitted by 
marine organisMs. Although studies based on MSA measurements show 
that the link between climate and biogenic marine activity could 
be more complex than initially thought, both nonseasalt sulfate 
and MSA records indicate that the ocean-atmosphere sulfur cycle is 
extremely sensitive to climate change.  Sulfate aerosols affect 
climate by "thickening" the atmosphere.

Air Sampling

Air initially enclosed in Vostok ice provides our only record of 
variations in the atmospheric concentrations of CO2 and CH4 over a 
complete glacial-interglacial cycle.  For both greenhouse gases, 
concentrations are higher during interglacial periods than during 
full glacial periods.  Since preindustrial times, levels of CO2 
and CH4 have increased sharply.  A close correlation between these 
gas concentrations and the Vostok isotopic temperature has been 
confirmed by extending the record over part of the previous cycle.  
However, at the end of the last interglacial, the CO2 decrease 
significantly lags Antarctic cooling, while CO2 and Antarctic 
temperatures increase during the warmings of the glacial-
interglacial transitions.  Interestingly, at least during certain 
deglaciation periods, the trace gas increase precedes the onset of 
most melting of the northern ice sheets by several thousand years.

From a climatic viewpoint, CO2 and CH4 have played an important 
role.  Together with the growth and decay of the Northern 
Hemisphere ice sheets, these greenhouse gases have amplified the 
initial orbital forcing, and they account for about half of the 
glacial-interglacial climate changes.  This supports the idea that 
significant greenhouse warming will occur in the next century.

Ice sheet modeling is used to date ice cores and study long-term 
interaction between climate and the dynamics of large ice sheets.  
Information gained from studies of ice texture and fabric, ice 
rheology, and ice densification is crucial to this objective.  
Models predict that the ice sheet over Vostok will thin during 
cold periods.  In agreement, the long-term trends of total air 
content in the ice show that during colder periods air pressure 
was higher.  This supports the idea that elevation of the ice 
sheet was lower.  Other studies confirm that microorganisms--
including species that have disappeared elsewhere--could survive 
in the deep Antarctic ice for many thousands of years following 
anabiosis.

Sample Analysis:  Preliminary Results

In France and the United States, analysis of samples of the last 
200 m of core 5G are nearly complete and exciting results have 
emerged.  The bottom part of the core (2755 m) corresponds to an 
age of 240 kyr B.P., reaching back to the penultimate interglacial 
period.  The warmest part of this penultimate interglacial was 
likely as warm as today in Antarctica.  One of the most remarkable 
result derived from this new record is the striking similarity of 
the last two climatic cycles, which is not documented in any other 
paleorecord.

GLOSSARY

Chronology- Arranging events in their proper sequence.
Cosmogenic Isotope- An isotope that can be used to study the age 
and origin of the Earth.  
Forams- A family of aquatic microorganisms that are important as 
age indicators, as rock-building agents, and in seafloor deposits.
Fractionation- The separation of chemical elements in nature.
Ice Age- A time of extensive glacial activity also called a 
glacial epoch (see definition for Pleistocene).
Ice Sheet Modeling- Ice sheet models incorporate ice-flow laws 
that account for the mechanical and thermodynamical properties of 
the ice.
Interstadial- Warmer substage of a glacial stage, marked by a 
temporary retreat of the ice.
Isotope- A particular atom of an element that has the same number 
of electrons and protons as the other atoms of the element, but a 
different number of neutrons.  The temperature at which an oxygen-
bearing geologic material formed can be determined by studying the 
oxygen isotope it contains.
Minima- Time or position of the greatest retreat of a glacier.  
Pleistocene- The "Great Ice Age," during which glaciers and ice 
sheets covered the land masses 4 times over 2 million years ago.  
These massive ice advances were separated by longer warm 
interglacial periods.
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CASSINI MISSION STATUS
JPL release

3 March, 1998

The Cassini spacecraft successfully performed the second scheduled 
trajectory adjustment of its mission last week, fine- tuning its 
flight path in preparation for its flyby of Venus on April 26.  
The trajectory adjustment needed was so minor that the maneuver 
was performed using Cassini's small hydrazine thrusters instead of 
the spacecraft's large main engine.  Engineering data recorded 
during the thruster firing confirmed that the maneuver went as 
planned, with all spacecraft and ground components performing 
perfectly.  A final trajectory adjustment prior to the Venus flyby 
is scheduled in early April.

Cassini remains in excellent health, flying at a speed relative to 
the Sun of approximately 137,000 kilometers per hour (about 85,000 
miles per hour).  It is slowly gaining speed as it feels the tug 
of gravity from Venus.  The spacecraft will gain a significant 
boost in speed when it swings around Venus next month.  Cassini 
has traveled approximately 362 million kilometers (about 224 
million miles) since launch on October 15, 1997.
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STARDUST STATUS REPORT
by Ken Atkins

27 February, 1998

STARDUST Assembly, Test and Launch Operations (ATLO) made good 
progress this week with telecom interface tests nearing completion 
today.  A solution was developed for the data transfer problems 
discovered in the Cometary and Interstellar Dust Analyzer (CIDA) 
interface testing last month.  Plans show the upgraded electronic 
simulator box arriving from Germany next week to support 
validating and testing the fix.  New ATLO flow plans allowed the 
CIDA team two weeks of schedule relief for their flight unit 
delivery.

The flight Sample Return Capsule (SRC) canister bake-out was 
completed to provide the required clean environment for aerogel 
collector tray installation.  The SRC avionics completed 100 hours 
burn in and the certification was completed to permit flight 
installation.

Fault Protection workshop #3 was held this week in order to 
concentrate on Fault Protection test planning and execution.  
Results were very good, indicating a thorough test program for the 
fault protection software.

The flight solar arrays completed functional lighting tests and 
acoustic test.  The first chip containing public names, letters 
and pictures has been installed on the SRC avionics deck.

For more information on the STARDUST mission--the first ever comet 
sample return mission--please visit the STARDUST home page:
http://stardust.jpl.nasa.gov/
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End Marsbugs Vol. 5, No. 5


