Panspermia has been defined in several ways
The American Heritage Dictionary definition of Panspermia:
n. The theory that microorganisms or biochemical compounds from outer space are responsible for the originating life in earth and possibly in other parts of the universe where suitable atmospheric conditions exist.
The idea that life on earth was seeded from space has its roots in ancient Greek philosophy. Thus it should come as no surprise that Panspermia has it’s origins in a Greek word that literally means “seeds everywhere.” Panspermia does not try to explain the origin of life itself, but the proliferation of life through the universe.
Although panspermia has been a subject of discussion by scientists since the 1700’s, there was little evidence of it until the mid-1990’s when a meteorite of Martian origin, named ALH84001, was found and believed to contain fossilized bacteria. In December of 2009, NASA scientists using newly developed methods examined ALH84001 and concluded that biological remains were the most plausible explanation for the materials and structures found in the Mars meteorite. As interesting as ALH84001 was, however, it was not until unmanned space exploration that the mainstream scientific community began to embrace the theory.
Despite the fact that life has not been found in space, unmanned spacecraft are quickly finding mounting evidence of at least some extraterrestrial input to the formative stages of earth biology. Space probe missions Deep Impact , Stardust, Cassini , Chandrayaan-1 and LCROSS in aggregate have found all the necessary elements for life in space- clay, organic molecules and water.
The Foton-M3 spacecraft carried various simple earth life forms on a 12-day round into space in a capsule that exposed them to the outside space environment and cosmic radiation. After a fiery reentry by Foton-m3, bacteria, lichens, spores and even one animal (Tardigrades) were found to have survived the mission, thus proving that life could survive travel to earth. As you read this other probes, such as Dawn on its’ way to the dwarf planet Ceres, are searching for life in space that may have seeded life on earth.
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