Are we Made of Stardust?
By Anjana Ravishankar
Cosmofluencer (Season 2)
The basic building blocks for life on earth from time immemorial have been the genetic materials – DNA & RNA. The genetic material is a polymer made up of a purine/pyrimidine base, ribose sugar, and a phosphate group. In simpler terms, together, they are referred to as nucleic acids. That’s sufficient molecular biology to understand what’s coming next to fascinate you!
What if these genetic materials or precursors for life have signs of extraterrestrial origin? What if I told you that maybe some meteorites that crashed onto the Earth’s surface brought them along too? Well, it’s no more a ‘what if’ to wonder, according to the discoveries, research, and developments lately. Scientists have found that meteors have deposited the DNA building blocks on Earth’s surface. And these building blocks were formed in space!
In a paper published on 15 June 2008, scientists have confirmed for the first time that an important component of early genetic material that has been found in meteorite fragments is extraterrestrial in origin The finding suggests that parts of the raw materials to make the first molecules of DNA and RNA may have come from the stars.
In 2011, experts from the NASA team crushed and studied a collection of twelve meteorites from Antarctica and Australia. The scientists discovered a treasure trove of compounds within them that may have played a critical role in the formation of early forms of life. Adenine, which contributes to DNA’s helical, ladder-like structure, was found in eleven of the meteorites. Guanine, another important ingredient, was found in eight. Two of the twelve meteorites also contained some extraordinary exotic molecules that are so rare on Earth that they prove the DNA building blocks must have formed in outer space. The discovery gives credibility to the idea that life began as a kit of prefabricated parts from meteorites or comets.
Nucleobases, which are nitrogen-containing chemicals that function as the building blocks in DNA and RNA’s genetic code, have been discovered to exist in space rocks for a long time now. Adenine (A), thymine (T), guanine (G), cytosine (C), and uracil (U) are the five primary flavors of nucleobases; nevertheless, only A, G, and U have ever been found in meteorites before. One category of building blocks — pyrimidines — showed extremely low concentration in the meteorites. This discovery also, on the other hand, suggests that most of the world’s initial genetic molecules evolved as a result of geological processes occurring on early Earth rather than an influx of DNA components from space.
While phosphorus is rare in the universe, it is necessary for life (most of the time). It functions as the binding agent between the nucleotide chains that make up DNA. Phosphorus aids in the synthesis of cell walls and the energy storage of cells. Astronomers looked to the stars to determine how the element got to Earth.
When clouds of gas and dust collapse, they cave to gravity and condense into new cosmic objects. Massive stars emit gas flows that open large voids in the clouds of interstellar dust that surround them when they are still young. Scientists believe phosphorus molecules grow on the walls of these cavities as they are bombarded with radiation from the young, big stars.
The researchers used data from the Rosetta spacecraft, which orbited the 67P comet from August 2014 to September 2016.
Astronomers had earlier found a hint of phosphorus in Rosetta data on 67P, but they had not defined which molecule the element was a part of; it was mostly thought to be in the form of phosphorus monoxide.
Astrobiologists and various evolutionary biologists perceive that comets, meteors, and other space rocks may have delivered a few essential chemical components that acted as the precursors of life to early Earth. Well, isn’t it absolutely fascinating to imagine that even the smallest of our cells have components that originated from stars and celestial bodies?!
The famous astrophysicist Jocelyn Bell Burnell once said, “There is stardust in your veins. We are literally, ultimately children of the stars.” And I think it’s safe to conclude that we are made up of stardust with the scientific evidence we have! What do you think?