Was there ever life on Mars? Is there still life on Mars?
These are the questions that millions of people have asked since Percival Lowell first announced in 1895 that the deep ravines and 'canals' on Mars were created by intelligent beings. As humanity began studying The Red Planet they were ultimately able to refute this popular assertion, but whole generations grew up with tales of Martians and little green men. It led to fascination and hope that humanity was not alone in the universe.
The hope that intelligent beings lived on Mars was dashed in July 1965 when Mariner 4 flew past Mars and took the first close-up photographs of the Martian surface. Those pictures showed a desolate planet that resembles the Moon with its barren landscape and essential lack of atmosphere.
For those that still had hope that intelligent life once existed on Mars they became excited by the clear pictures taken by Mariner 9 in 1972, which gave evidence that water had once been abundant on the Martian surface. In the years since photos from other satellites orbiting Mars also led scientists to the same conclusion, that liquid water had once covered much of the Martian surface, but that it was now unable to exist on the surface. So while it was concluded that intelligent life was not present on Mars, the scientific community and the world at large still held out hope that some form of life existed on The Red Planet.
Evidence that Liquid Water Once Existed on the Martian Surface.
Evidence of Past Water Provides Hope
The evidence that water had one existed on the Martian surface gave scientists and the populous hope that life might have existed on Mars as well. However, scientists briefly had their hopes dashed when NASA's Viking Program brought soil samples from the Martian surface back to Earth. They could not discover any microbial life or evidence that life could actually exist in the soil of Mars. These findings were disputed though; many people believed that the method used to bring the samples back to Earth had killed any proof of life. Scientists and people everywhere were once again hopeful.
So if water had once existed on the Martian surface, perhaps it was possible that microbial life had existed as well. And if it was possible that microbial life
had existed, why couldn't it
still exist? Scientists were doubtful that it could still exist because the conditions are Mars were so severe that no known life could tolerate them.
The Discovery of New Life
This was the common consensus until a discovery on Earth led scientists to redefine the necessary parameters for life. In late 2010 NASA discovered bacteria in Mono Lake, California that did not use all the elements previously thought necessary to sustain life. The bacterium replaced phosphorous with arsenic, an element that was previously considered toxic and an impediment to life.
