Life beyond our planet Earth

-Subhrajit Barua, ITMO University, St. Petersburg, Russia

For numerous centuries, human beings have wondered how life came into existence. Many religious and philosophical ideologies have been put forward but none of them have been satisfactory. Some argue that life emerged on Earth itself from non-living chemical compounds through the process of abiogenesis. Many theories have been put forward to support this hypothesis including Charles Darwin’s famous “hot soup” theory. For many years people believed that the fundamental organic compounds essential for life are unique to Earth. 

The possibility of the emergence of life on Earth, based on organic molecules delivered to the Earth from space has become a subject of increasing interest in recent times. The analysis of carbonaceous meteorites has demonstrated that organic molecules, including amino acids, are formed in extra-terrestrial environments. Astronomical observations have also shown that some of these biomolecules were already formed before the sun even started to form, and were incorporated into planets and smaller solar system objects such as comets and asteroids. Owing to the extremely high temperatures on the planets during their formation, no organic molecules survived this epoch. The organic compounds necessary for the origin of life like amino acids, lipids, and nucleic acids were formed either later in the atmosphere (e. g. through Miller-Urey-type reactions) or were delivered to the early Earth by a large asteroid and comet impacts or by their fragments, the meteorites and interplanetary dust particles. The study of meteorites, particularly the carbonaceous chondrites that contain organic matter up to 5% by weight, has allowed the examination of extraterrestrial organic material. 

One of the most famous sources of extra-terrestrial material is the Murchison meteorite named after the Australian town where it landed in the year 1969, just three months after the first lunar landing of Apollo-11. Luckily, the techniques developed by NASA to study the lunar soil samples were apt for analyzing the meteorite as well. Among other classes of organic compounds, more than eighty different amino acids have been identified in the Murchison meteorite at abundances of more than 1 part-per-million (ppm), eight of which are identical to those prevalent on Earth as the building blocks of proteins and enzymes. Also, the presence of sugar-related molecules and nucleobases was confirmed, which forms the core of nucleic acids on Earth. 

Astrobiology is an exciting area of study for biochemists, geologists, and almost any space enthusiast. We, human beings are still looking for an answer to the mystery of the formation of life, and right now we are making humongous progress every day. The month of August 2020 witnessed the launch of three missions to Mars (Hope by UAE, Tianwen by China, and Perseverance by NASA) in a quest to study our neighbor better and look for signatures of past or present life.

Sources:

The article is based on the book named” Spatium” on “Astrobiology” by Dr. Oliver Botta, NASA Goddard Space Flight Centre and International Space Science Institute.

To find more articles, please visit https://bioxone.in//