Biology 103
2001 Second Web Report
On Serendip

For thousands of years, mankind never doubted that life existed anywhere except for on Earth. Yet as humans learn more about the world we live in, we are beginning to ask questions about what exists in the world beyond Earth. Exploring the moons and planets has been around for centuries, but only in recent years have people been able to study the solar system close-up. Now we have technology that allows for scientists to travel to the moon and study planets from spaceships that are able to land on, or orbit around, them. With the advancement of technology comes the advancement of new knowledge about the moons and planets that have been a mystery to mankind for so long. Every year, planetary scientists discover more evidence of a very complex solar system. A question that has plagued scientist for years is the driving force for many scientific explorations of the planets: Does life only exist on Earth? Are we alone? Until recently, it seemed highly unlikely that life existed anywhere except for Earth, but shocking discoveries on the planet Mars has given scientists new hope in their search for extra-terrestrial life.

Compared to Earth, the atmosphere of Mars is dangerously extreme. The Earth's atmosphere consists mostly of nitrogen and oxygen, with a slight amount of carbon dioxide. Yet on Mars, nitrogen and oxygen are present in trace amounts, while carbon dioxide makes up 95 percent of the atmospheric air. Because the air is so thin, the temperature on Mars averages about 81 degrees Fahrenheit. Most of the heat comes from solar radiation absorbed by the ground. Mars also has an extremely low atmospheric pressure. And because of this low pressure and the cold temperature, water cannot exist in a liquid form. It would either freeze or evaporate into the atmosphere. (1)

Yet there is evidence that water flowed on Mars at one point in time. In fact, it may even still be present on Mars. Even before space exploration began, astronomers thought they saw straight lines on the surface of Mars, indicating what they believed were irrigation canals made by extra-terrestrial beings. (3) But modern research has gotten a closer look at those lines. And indeed, scientists now believe that these straight lines that crisscross Mars' surface are possibly dried up river valleys and flood plains. Geological features resembling gullies, formed by flowing water, have been spotted on Martian cliffs and crater walls. (2) Scientists have also detected water in the atmosphere and underneath the polar ice caps of Mars. (1) The possibility of there being water on Mars is an essential component to answering the question of whether life has existed, or does exist, on the planet. Without water, life as we know it on Earth could not survive. Yet the persuading evidence of dried rivers and the detection of water in the atmosphere and under the polar ice caps has encouraged scientists to continue searching for signs of living organisms.

Due to state-of-the-art technology developed in the last few years, it seems that scientists' search for life has not been in vain. (3) The possibility of water and now the convincing evidence of fossil remains have opened the door to discovering life on Mars. (4) If water flowed on Mars at one time, it most likely did not last long enough for anything besides microscopic bacteria to develop. (2) But a meteorite that fell to Earth from Mars has provided substantial evidence of microscopic fossils of primitive bacteria. The 4.2-pound rock contains globules of carbonate that were possibly formed from water saturated with carbon dioxide that seeped into fractures of the Martian subsurface rock. It is believed that microscopic bacteria also aided in the formation of carbonate and became fossilized in a manner that is similar to fossil formation on Earth. Then, 15 million years ago, a piece of the rock was projected into space by a comet or asteroid that struck Mars. The rock floated through space until it landed on Antarctica 13,000 years ago. (3)

Within the carbonate globules of this rock, scientists have uncovered many clues that hint to past life on Mars. Detectable amounts of organic molecules called polycyclic aromatic hydrocarbons (PAHs) were found on the interior of the meteorite. PAHs are formed when microorganisms die and their complex organic molecules degrade. Scientists also discovered mineral compounds, such as iron sulfides and magnetite, commonly associated with microscopic organisms like anaerobic bacteria found on Earth. The fossil remains found in the meteorite are quite similar to the fossils of microscopic organisms that have been discovered on Earth, leading scientists to believe that at one time life existed in some form on Mars. (3)

As of now, it is impossible to prove that life exists on Mars because of the lack of water on the planet. But intensive research and space exploration has produced evidence that supports the theory that both water and life existed on Mars billions of years ago. Though no piece of evidence is entirely conclusive, each new discovery provides more and more information about the possibility of life on Mars. And indeed, with each new exploration it seems that scientists are getting closer to proving that life may exist beyond our own world.

WWW Sources

2)Mars Exploration. ,

3)Mars Introduction. ,

3)Mars Surprise. ,

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