Panspermia
Panspermia is the theory that life originated from outer space and landed on Earth, to produce life. This theory suggests that life originally existed on another planet and was transported to Earth. The theory asserts that once the substances arrived from space, they became proteins from amino acids and then into life (if not already)(Panspermia Theory, http://leiwenwu.tripod.com/panspermia.htm). Possible explanations of Panspermia include the deflection of interstellar dust by solar radiation pressure or extremophile micro-organisms travelling through space within an asteroid, comet or meteorite( 2009, Panspermia and the Origin of Life on Earth, ). Despite Panspermia being a widely supported theory, there are different variations of Panspermia.
Lithopanspermia
This is the variation in which impact-expelled rocks (carrying biological material) are transported from the surface of a planet in one solar system to another planet from a different solar system.
The biological material then created the first life-forms on the planet.
The biological material then created the first life-forms on the planet.
Ballistic Panspermia
This theory is similar to Lithopanspermia in that impact expelled rocks (carrying biological material) are transported from one planet to another, however in Ballistic Panspermia both planets are within the same solar system.
Directed Panpermia
This is the variation in which an advanced extraterrestrial civilization intentionally spread the “seeds of life to other planets”(2009,Directed Panspermia,). This variation of Panspermia has been developed by several different scientists, but Nobel Prize winner Professor Francis Crick (the co-founder of the double helix structure of DNA molecules) is the most famous scientist to develop the theory. His hypothesis was al civilization of advanced, intelligent beings and that their planet was to be destroyed. His hypothesis was that these beings left their planet and travelled through interstellar space until they found a suitable planet to colonize. In support of his theory Crick is quoted "You would be more likely to assemble a fully functioning and flying jumbo jet by passing a hurricane through a junk yard than you would be to assemble the DNA molecule by chance. In any kind of primevalsoup in 5 or 600 million years, it’s just not possible"(Directed Panspermia (Part2), 2011.).
Radiopanspermia
This is the theory in which individual cells travel interstellar distances and are propelled by solar light pressure.
For this theory to be valid, the cells would require a coating of carbon to protect them from UV radiation and several metres of water or rock surrounding it to protect it from cosmic rays.
For this theory to be valid, the cells would require a coating of carbon to protect them from UV radiation and several metres of water or rock surrounding it to protect it from cosmic rays.