is the hottest planet in the Solar System. It is too hostile
today to harbor life as we know it. The runaway greenhouse
effect, caused by its dense atmosphere, drives surface temperatures
to uninhabitable levels. If life did exist it did so long
ago, when conditions were more Earth-like. The USA and the
Soviet Union began studying Venus in the early 1960's with NASA's
Mariner II Mission and the early Venera series of spacecraft.
Pioneer Venus, various Soviet Venera missions
and the Magellan mission also provided information
about the surface of the planet in the years that followed.
Although controversial, data suggest that ancient lakes may have
once existed on Venus. The planet may have had a large volume
of water in its atmosphere and on its surface, in the distant
past when the climate was cooler.
large bodies of water did exist, they could have lasted for several
hundred million years until they boiled away as temperatures rose.
Icy comets , or volcanoes, could have resupplied the oceans for
a billion years or so. Electrical activity in the atmosphere
and volcanic activity in the mantle would have been important
energy sources for the production of organic chemical compounds,
similar to those that can be produced by the Miller-Urey experiment.
But this is a long way from the creation of life and any speculation
about life developing independently on Venus must remain just
that. For even if we can one day find a means of exploring
the planet, virtually all traces of the existence of life will
have been obliterated by the heat and active chemistry.
to note however is that Venus, like the Moon and Mars, will have
been a recipient of Earth rocks through impact ejection.
So once again life could have been transported to Venus, as it
certainly may have been to the rest of the Solar System.
It could have found a suitable home to thrive, but as Venus become
hotter under its blanket of runaway green-house gasses, life would
have become intolerable even for the most robust archaean thermophile.
All images NASA, unless shown