FREE ESSAY ON MARS: LIFE, DEATH, HOPE?

MARS: LIFE, DEATH, HOPE?

Venus is the 2nd closest planet to the Sun, and the closest planet to Earth. Venus can
reach visual magnitudes (brightness) of -4.4, making it the brightest object in the night
sky, excluding the moon. Venus was once considered Earth's twin, a swampy place with
oceans and strange creatures were imagined. After sending probes such as Mariner, Pioneer
Venus, Venera (which landed on Venus), Vega, Magellan and Galileo, we know that Venus is
the victim of a run-away greenhouse effect. Mars is the fourth planet from the Sun. If
Venus is the planet with a runaway greenhouse effect, then Mars is the antithesis; it
doesn't have enough Carbon - Dioxide to trap enough of the Sun's energy for water to
remain in liquid form. The lack of water between these two planets seems to be one of the
contributing factors to the fact that there is no life on these planets. Mars is our hope
for starting colonies on other planets, so we must look at how other planets close to us
developed in order to tell how Mars would develop in the future. We must also see if Mars
was ever capable of having water, and even supported life in the past. 
The atmosphere of Venus, which is mostly Carbon - Dioxide (98%), traps most of the Suns
infrared rays, heating the surface of the planet beyond the melting point of lead. If
there were oceans there, they boiled away long ago. Venus is believed to have a plate
tectonic system that is much different from the plate system on Earth. Recent events have
decided that if there is a plate system, most likely they are far beneath the surface or
so far from our system that it is hard to call it the same type of system. Even though
the plate system is far different from our own, it still circulates the crust to keep the
planet changing.
The Martian surface does not show evidence of plate tectonics, so the continuous
recirculating of the crust does not occur on Mars. It is believe this would have doomed
Mars from the start to the thin atmosphere and desert conditions which exist on the
planet today. The atmosphere is comprised mostly of Carbon - Dioxide (95%), nitrogen
about 3%, argon about 1.5%, oxygen about 0.15%, and trace amounts of water vapor and
other elements. Even though Mars atmosphere contains a lot of Carbon - Dioxide it is just
too thin to obtain thermal equilibrium with the surface or with space to generate a
warmer environment by the greenhouse effect. The Viking spacecraft which landed on Mars
in 1976, tested for the presence of life in the soil of Mars, using a series of three
tests. The results were mixed, but are generally accepted as negative, that life is not
now present on Mars. 
The Mars Pathfinder mission in September 1997 provided some evidence that Mars was once
much warmer than it is today and that liquid water once flowed over its surface.
Observations by Mariner spacecraft, showed the canals were a myth, and revealed the
darker areas to be areas of bedrock, possibly exposed and covered by Mars powerful winds.
Mars is dotted with numerous impact craters, volcanoes and ancient river beds. The
presence of riverbeds and evidence of erosion due to flowing liquid water indicate that
Mars once was much warmer, possibly due to volcanic activity, changes in axial tilt, or
some other cause. The atmosphere that surrounds Mars today is insufficient to provide a
climate warm enough for water to flow. NASA has this to say about the Martian surface 
Mars and Water Mars today is too cold, with an atmosphere that is too thin, to support
liquid water on its surface. Yet scientists who studied images from the Viking orbiter
kept encountering features that appeared to be formed by flowing water - among them deep
channels and canyons, and even features that appeared to be ancient lake shorelines.
Added to this were more recent observations by Mars Pathfinder and Mars Global Surveyor,
which suggested widespread flowing water in the planet's past. Some scientists identified
features which they believe appear to be carved by torrents of water with the force of
10,000 Mississippi Rivers. 
There is no general agreement, however, on what form water took on the early Mars. Two
competing views are currently popular in the science community. According to one theory,
Mars was once much warmer and wetter, with a thicker atmosphere; it may well have boasted
lakes or oceans, rivers and rain. According to the other theory, Mars was always cold,
but water trapped as underground ice was periodically released when heating caused ice to
melt and gush forth onto the surface. Did life arise on Mars? We do not have a definitive
answer; only a direct study of the Martian soil, and rocks can answer this question. The
answer may lie in the answer to the question did water ever exist on Mars. We must study
things like the plate systems on Venus to help us understand how planets themselves
evolve, and how it would have changed the planet Mars to the point of eliminating all
life and future advancements of life on its surface. If there is water in under the
surface of Mars, we may be able to access it, if we find a way to create a false
greenhouse effect. 
Bibliography
Works cited
Mars, Water and Life. NASA. 3 Ocotober 2000