Are we alone in this universe? Are there living beings in another part of the universe wondering about alien life just like we do? If they exist, do they look like us, think like us? Humans have always been curious about these questions. We currently don’t have answers to them. But the research in this field has led to the discovery of biomolecules on many space rocks. These discoveries help us get the keys to unlock the puzzle of alien life.
Let’s begin our exploration of biomolecules on extra-terrestrial rocks from Earth’s twin planet, Mars. There have been numerous missions to Mars exploring the possibility of whether life existed on the red planet once upon a time. Out of them, NASA’s “Curiosity” has discovered evidence for organic molecules in some three billion years old Martian rocks. Organic molecules discovered by Curiosity include toluene, benzene, thiophene, and organic molecules with small carbon chains like butene and propane.
We now know that organic molecules need not be of living origin. They can be produced by abiotic processes also. As of June 2018, the origin of those organic molecules was not known with certainty. Therefore, we cannot arrive at conclusions just by looking at the discovery of those molecules. But this discovery has definitely made researchers more hopeful about the possibility of extraterrestrial life that could have once existed on the planet. This is expressed by ‘Thomas Zurbuchen, associate administrator for the Science Mission Directorate at NASA Headquarters, in Washington’ when he said, “With these new findings, Mars is telling us to stay the course and keep searching for evidence of life.” Further, organic matter has been discovered in interstellar clouds, comets, meteorites, etc.
In 1994, Miao and Kuan (of the University of Illinois at Urbana) and other collaborators reported the detection of the amino acid glycine in the star-forming region Sagittarius B2 near the centre of the Milky Way.’ Amino acids, if you didn’t already know, are building blocks of proteins. Eight years later, in 2002, “Max Bernstein of NASA’s Ames Research Center and colleagues”, in a laboratory recreated the conditions that we consider to exist in interstellar clouds. It shouldn’t surprise you to hear that they could produce three amino acids(glycine, alanine and serine) in the laboratory.
Polycyclic aromatic hydrocarbons (PAH) could probably be the most abundant organic molecules present in space. PAHs, as the name suggests, are hydrocarbons that consist of multiple aromatic rings. They are considered the starting materials for processes that lead to the formation of abiotic materials required by the earliest forms of life. Isn’t it amazing? Now let’s come back to earth. We need not go elsewhere to look for extraterrestrial organic molecules. They are here buried deep inside our earth. Scientists reported the presence of organic molecules from over 3.3 bya buried deep inside the volcanic sediments of the Makhonjwa Mountains in eastern South Africa. In our lifetime, we might never get to see the discovery of full-fledged organisms in extra-terrestrial rocks. But the advancements in the field are mind-blowing in their own right.