QUESTION:
Could the biological tests carried out by the two Viking landers have
formed pre-cursor molecules of life?  What chemicals were used in the
Viking tests? Could they have formed amino acids over a long period of 
time?

ANSWER from Jack Farmer on January 19, 1999:
The Viking Biology experiments were carried out in a carbon
dioxide/carbon
monoxide atmosphere similar to Mars. Mixes of simple amino acids,
vitamins,
salts (and in the case of one experiment, a radioactively-labelled
nutrient)
were dissolved in water and added to Martian soil. The soil had been
scooped
up by the the robotic arm of the landers and delivered to small reaction
chambers. The gases in the chambers were then monitored to see what
gases
were given off. After more than two decades of analysis, the results of
these
experiments have been widely accepted as indicating only inorganic
responses.
These experiments were all conducted inside small enclosed chambers on
the
landers and not in the Martian environment. Still, if we assume that
some of
these materials were released into the Martian soil, it still seems
unlikely
they would survive very long to participate in pre-biotic chemistry of
the
kind that we think produced life on Earth. The Martian soils appear to
be
barren of organic molecules even though simple carbon compounds (e.g.
amino
acids) are constantly being delivered to the surface with meteorites and
interplanetary dust particles. The Gas Chromatography-Mass Spectrometer
experiment on Viking could have detected such simple organic compounds
at a
concentration of one part in a billion. Yet none were found -- not a
single
carbon compound! This suggests that a strong oxidation process occurs in
the
Martian soils (probably involving peroxoide-like compounds) which
constantly
breaks down any introduced organics. Thus it seesm most probable that
any
simple organics introduced into the Martian environment during Viking
would
have been quickly oxidized to carbon dioixde. 

In conclusion, I would say that it seems quite unlikely that during
landed
missions forward contamination of Mars by simple organic compounds could
lead
to a complex prebiotic chemistry of the type required for life. What
remains
unclear is the fate of terrestrial organisms introduced into the Martian
environment. If living organisms from Earth were introduced, could they
survive in a dormant state, resisting degradation and destruction by the
hostile chemical environment of Mars. We know that many Earth organisms
have
evolved very resistant resting stages (spores or related things) that
allow
the orgnaism to weather over many harsh conditions, germinating to an
active
life form when (and if) favorable conditions arise. Could this also be
the
case on Mars? Clearly we need to understand a lot more about the nature
of the
Martian soil oxidants and their chemistry, as well as the ability of
terrestrial organisms to survive for prolonged periods under inclement
conditions. 

Understanding the soil oxidant chemistry on Mars was a focus for an
American
experiment flown on the failed Russian lander mission launched in 1996.
That
experiment, called "MOx", was designed to collect an array of
sophisticated
data on the oxidation processes in surface soils using fiber optic
technology.
It is hoped that we will be able to re-fly such experiments in the
future. 

Jack Farmer