Life on Mars?
Posted October 1st, 2002
Since humans first gazed into the heavens to look at the stars, they wondered about life on other planets. When humans first realized that some of those twinkling
stars in the sky were, in fact, nearby planets circling the sun, people soon wondered if life existed on some of our closest neighbors.
Mars, the planet with the closest orbit to Earth, has been the subject of speculation for many years. In the early 1900s, science fiction author Edgar Rice Burroughs
wrote a series of fantasy stories about Martians battling Earthlings. For the next century, science fiction authors have written about life on Mars, including the world famous Martian
Chronicles by Ray Bradbury.
NASA's early data from Mars, which was gathered from the Viking probe in the 1970s, suggested that the red planet was a barren wasteland. However, in 1996, scientists
from the Johnson's Space Center announced they had found possible evidence of life in an ancient meteorite found in Antarctica. The rock, which had a composition that suggested it was
Martian in origin, contained the right chemistry for life.
In the late 1990s, NASA sent Mars Pathfinder on a mission to travel to Mars and examine the planet again. While nothing in the collected data suggested any conclusive
evidence of life on Mars, scientists went over the data again earlier this year. Now, they say they have found evidence of possible "hot spots" of chlorophyll. Chlorophyll
is important to life because it is the chemical that allows plants to use sunlight to convert water and carbon dioxide into food. If chlorophyll exists on Mars, there is a very good
chance that life could exist there as well.
Don't expect to see little green men coming from Mars to Earth as ambassadors though. Scientists agree that if life does exist on the red planet it is microbial in
nature.
One type of microbe that might be living in the Martian atmosphere is a special type of bacteria called methanogens. These bacteria do not use chlorophyll, but rather
metabolize hydrogen and carbon dioxide, which is abundant in the thin atmosphere of Mars. Researchers at the University of Arkansas have completed experiments to show that methanogens
can survive in atmosphere and soil similar to that found on Mars.
These findings, along with the fact that there appears to be vast underground deposits of water on Mars, lead scientists to believe that life once did exist - and
might still - on the red planet.
Activity
Use the Internet to research the possibility of life on Mars. In your Science Journal, write a science fiction story, using real data, about life being discovered
on the red planet.
References
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