The Search for Life on Mars

For decades, interest in life on Mars has been increased by common depictions of Martians in film, television and other media. H.G. Wells’ War of the Worlds inspired the overactive imaginations of millions of Americans and in subsequent years, dozens of titles have released that feature extraterrestrial life. An obsession with Martians is not simply a media fad; for over a century, scientists have had a great deal of interest in the possibility of life on Mars. Astronomers of the late 19th century and early 20th century had grandiose visions of Mars, which contained possible rivers and canals; geographic signals that life must exist on the planet. As science progressed however, it was realized that Mars was now a dry, red planet without a magnetic field and the constant presence of sand storms. Though the iconic large green head and oval black eyes are merely the work of fiction, the search for life on Mars has not ended. In the mid-1970s, the Viking 1 & 2 missions would give the United States its first real chance to find tangible evidence of life on Mars.

The Viking 1 & 2 missions would be the first probes to take soil samples of another planet. The two Viking orbiters launched on August 20, 1975 (Viking 2) and September 9, 1975 (Viking 2) and reached Mars on June 19 and August 7 of the following year. Once the orbiters established positions in Mars’s orbit, Landers were sent to the planet’s surface. The Viking Landers were equipped with a variety of state of the art instruments that included biology sampling tools, X-ray fluorescence spectrometers, seismometers, and cameras. After the Viking Landers reached the surface, they set out on their task of gathering Mars ground samples, which would allow them to look for biological evidence of microbial life. Much to the disappointment of scientists, most of the tests returned with negative results. There was however, one test that presented interesting findings; after exposing Mars soil to water and nutrients there was increased production of 14CO2. Unfortunately, the excitement of this finding was short lived, because additional instruments on the Viking Landers did not detect any type of natural organic matter. Although the scientific community concluded that this was not a sufficient sign of life, it did raise a host of new questions that needed to be answered to fully understand Mars’ ability to support life in the past and present.

The Viking Landers and Orbiters would continue their missions until November of 1982 (Viking 1) and April 1980 (Viking 2), but this did not mark an end to the search for life on Mars. Though conclusive data was not discovered during the Viking missions, NASA continues to make plans to explore Mars more thoroughly in the future. One Mars Rover, from the early 2000s mission, is still active on the planet today. Additionally, the future holds several missions to Mars including NASA’s Mars Science Laboratory, the European Space Agency’s ExoMars program and hopes of the Mars Sample Return Mission, which would allow for samples to be brought back to Earth to be analyzed. Scientists realize the many difficulties and limitations of trying to find life on a planet, and even though, to this point, no definitive signs of life have been discovered, they are not discouraged, only hopeful.

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