you know, at this time we do not have reason
to believe that there is currently life
on planets other than Earth. We do, however,
think that it is possible that life did
exist on other planets at some time. Let's
talk today about our neighbor planet, Mars.
We have already talked about the existence
of water on Mars many years ago.
evidence for the existence of water comes
from photographs that were taken from satellites
that investigated Mars. These photographs
showed cracks in the surface of the planet
that indicate that rivers had once been
there. Other pictures showed that there
were probably also glaciers on the planet
at one time.
what is this new information that we have
about the possibility of life on the planet?
I am sure you have all heard of meteors,
right? In case you haven't, a meteor is
a piece of rock that breaks off from a planet.
The meteor then flies through space until
it lands somewhere else. In this case, a
meteor flew off of the Red Planet and landed
scientists that found this meteor first
had to determine that it came from Mars.
Once they determined that the meteor was
from Mars, they analyzed the meteor. The
scientists found that the meteor contained
some of the same chemical elements that
are essential for life. That is, these same
chemicals are seen in dead micro-organisms
- that is, tiny animals - on Earth.
also found some minerals in the meteor that
are also found in living organisms. Finally,
they found some tiny "globules"
that they believe may be tiny fossils of
primitive bacteria. In short, they found
some of the forms of what could have been
a very old kind of bacteria. All of these
things they found in the meteor.
all of this hard evidence for life on Mars?
Not exactly. The meteor may have become
contaminated when it struck the Earth. Elements
from Earth may have stuck into the meteor
upon impact. The scientists may have also
contaminated the meteor with bacteria from
their own hands while transporting the meteor.
type of contamination, although common,
could disprove any idea of early life on
Mars. The elements in the meteor could really
be bacteria from our own planet, the Earth,
and not from Mars at all.