QUESTION:
[NOTE: This question contains two stated facts followed by one question,
which in all three the expert has answered.  The questions are within
his answers.] 

ANSWER from Jack Farmer on September 18, 1998:
Question: The Viking project collected samples of the Martian surface
in wich they found radioactive nutrients.

Answer: Viking collected only soil samples. These were analyzed for
signs
of life by adding water and nutrients to see if any metabolic products
were
given off that might indicate the presence of organisms. Theere were
products given off and some mimicked life processes, but were ultimately
shown to be due to inorganic reactions. Viking could not analyze for
radioactive compounds in the soils, except for radioactive carbon which
was
added to the soils and later recovered in carbn dioxide liberated by
chemical reactions in the soils.

Question: If life really exists on the surface, the radioactive
nutrients
could be used to their reproduction.

Answer: There is no compelling evidence for life on Mars based on the
Viking
results. All the Viking Life Detection experiments were ultimately
explained by inorganic processes. Also, when the soils were analyzed for
organic compounds, not a single molecule was discovered, even through
they
could have been detected at a concentration of one in a billion! There
are
in fact good reasons life was not found in the surface environments
sampled
by Viking. First, there is no liquid water. Water is essential for
organisms on earth and is needed to carry out the basic biochemistry of
their metabolism. No water means no life, at least as we understand it.
Second, the surface of Mars gets a heavy dose of ultraviolet radiation
that
is very harmful to organisms. We can imagine ways around this if
organisms
could "hide" in areas shaded from heavy radiation, or if they produced
pigments or external coverings that could absorb harmful wavelengths.
But
the UV dose on Mars is 3-4 times that at the surface on Earth, and most
organisms would probably not survive. Third, the soils of Mars are
loaded
with harsh, oxidizing chemicals (peroxides) that are very destructive to
organic compounds that organisms use and are made up of. Together, all
these things make the surface of Mars a very inhospitable place for
life.
But life may exist in the deep subsurface of Mars where liquid water
could
be present. These environments were not sampled by Viking, and
unfortunately, it may be some time before we can drill down to explore
those depths.

Question: Explain how the experiment proves scientifically the prescence
of life in Mars.

Answer: We presently have no proof for Martian life, past or present.
The sugestion of fossil life in a Martian meteorite is not well founded
and has largely been disputed by scientists since the announcement a
couple
of years ago. The goal of the next decade of Mars missions is to search
for that evidence.