Ultraviolet radiation is a somewhat different problem, because it is
hard to conceive of Martian organisms that would not be damaged
by ultraviolet, if it reached them. But several
protections seem possible. Dust in the air would reduce ultraviolet
durig storms.
Similarly, Mars likely has plenty of iron-breaing silicates in its soil, and
perhaps orgnaisms there have evolved silicate shells like those of diatoms, tiny
algae in the sea, with ultraviolet-blocking pigments.
Dr Sagan, on the other hand, has always beenoptimistis about the question of varied
life on Mars. Only a few months ago he told me
I wouldn'tbet too much money against fiding complex life-forms there. He added,
there is no reason to believe or disbelieve that there are
larger organisms on Mars. Mars has had 4.5 billion years for independent ultraviolet martian organisms evolution.
Therefore, the Martian organisms, if any, are not like us.
The slate is clean on that subject. WE won't know until we land.
