What is panspermia?

Hint: Panspermia is a theory that supports the idea that life originated from microbes present in outer space. This theory is based on the hypothesis that microbes and amino acids came on earth through meteors. The evidence to this theory is the capability of microbes to live and survive in harsh space-like conditions.

Complete answer: Panspermia is a hypothetical theory which states that life exists throughout the universe. The theory believes that life is distributed in the form of microbes and amino acids by space dust, asteroids, meteoroids, comets, etc. It supports the hypothesis that life may have distributed by spanning galaxies, and may not be restricted to the limited scale of the solar system. The hypothesis is simply based on the fact that microorganisms can survive harsh conditions of radiation and stay dormant for long periods. Based on this study, the theory states that life on earth may have been transported by a meteor carrying dormant microbes and amino acids. The theory dates back to the 5th century BC by a Greek philosopher named Anaxagoras. Later in 1903, the Swedish chemist Svante Arrhenius gave the panspermia hypothesis detailed scientific support. Currently, based on the panspermia hypothesis it is believed that extraterrestrial life exists. Based on this hypothesis now there is a broad field of study named astrobiology. Under astrobiology, various experiments have been conducted to support panspermia. The results were astonishing as bacteria survived in an inactive stage in the cosmic radiations. There are three types of panspermia theories named lithopanspermia, ballistic panspermia, and directed panspermia.

Note: Astrobiology is an emerging field related to the study based on extraterrestrial life. Three astrobiological experiments have been conducted by ISS (International Space Station) between 2008 and 2015. The experiments involved exposure of a wide variety of biomolecules, microbes, and spores to solar flux. The exposure period was for 1.5 years.