June 1, 2021 7:06:46 pm
In 2008, a team of scientists from Nasa’s Johnson Space Center and the Carnegie Institution of Washington discovered whisker-shaped graphite embedded in two distinct meteorites that contained minerals older than the planets in this solar system.
A decade later, Chaitanya Giri, an Indian-origin and ELSI Origins Network (EON) scientist at the Earth-Life Science Institute of Tokyo Institute of Technology, revisited the same meteorites with the same scientific team, to find signatures of a novel material, graphene.
Graphene is the thinnest slice possible of graphite. It is two-dimensional, exceptionally light, transparent, flexible, has tremendous physical strength, and extraordinary electronic properties. The excitement surrounding graphene has only soared to dizzying heights since Andre Geim and Konstantin Novoselov were awarded the 2010 Nobel Prize in Physics for finding a method to isolate it.
“This is the first study to identify unambiguous Raman spectroscopic signatures of isolated graphene embedded in calcium-aluminium-rich meteoritic minerals that is considered to be as old as 4.5 billion years, older than all the planets in the Solar System. Before this, graphene was only astronomically detected with telescopes around a dying star. The reason our discovery is important is that it provides physical evidence of the presence of naturally-formed graphene in extraterrestrial materials. As cosmochemistry progressed with time, scientists were gradually finding carbon materials such as fullerenes, nanodiamonds, older-than-the-Sun (pre-solar) carbon, and graphite in meteorites. Our detection can be considered as one of the stepping stones in this illustrious history of carbon-focusing cosmochemistry,” Dr Giri told indianexpress.com.
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Dr Giri, a product of Mumbai varsity
Giri, who finished his Master’s in Biophysics and Bachelor’s in Chemistry from the University of Mumbai, spent his doctoral years at the Max Planck Institute for Solar System Research in Germany. He was earlier a co-investigating scientist on European Space Agency’s Rosetta Mission that achieved the impossible – landing a robotic spacecraft on a comet.
This peer-reviewed study came out of research supported by the John Templeton Foundation and published on May 27 in the Planetary and Space Science Journal.
“The fact that evidence of graphene was identified in not one but two meteorites, each with different formation and subsequent history in outer space, makes it a compelling study. The graphene signatures detected here have all attributes of naturally-formed graphene than lab-made pristine graphene. Synthetic graphene is usually made in laboratories under controlled conditions because scientists usually know what they want to synthesize. The meteoritic graphene identified in the study has structural deformities: it is bent, twisted, curved, suspended and has elemental impurities. These deformities are because nature, especially when it is in its harshest avatar in outer space, is not predetermined to form synthetic graphene,” Dr Giri said.
The presence of carbon materials like graphene and graphite whiskers in the universe has been predicted by astrophysicists for more than fifty years. “Since the 1960s, a group of eminent astrophysicists from India and the United Kingdom had predicted the role of graphite whiskers in absorbing ambient heat from Type-1 supernovae, the blasts that occur at the terminal stages of some stars, and emitting heat slowly like glowing embers over long periods. The slow heat emission is known as Cosmic Microwave Background and many of us have felt it in an unsophisticated way as granular static on old-school antenna-connected TV sets. My co-authors, Andrew Steele and Marc Fries found similar whiskers’ first physical evidence in meteorites and lunar Apollo samples.”
Giri explained, “Graphite whisker resemble a single or a few sheets of paper rolled up unevenly and pulled out from its thinner end. If graphite whisker is akin to rolled-up paper, graphene is the sheets.”
Graphene has stimulated tremendous interest in electronics, semiconductors, advanced materials, space, telecommunications, aerospace, and space-based manufacturing industries. The European Union, the United States, South Korea, Japan, Singapore, Israel, and the United Kingdom have already made multi-billion dollar public-private investments in the research and development of graphene.
“A large natural reservoir of graphene will be of interest to cosmochemists and planetary scientists, and also to space startups and all these industries. It is important to comprehend, outer space is a treasure trove of exotic chemicals and materials. We must explore space for them and our curiosities and necessities,” he added.
But what has excited Giri and his co-authors is that this identification of graphene in the meteorites hints at its presence in the minerals on carbonaceous asteroids, comets, and the Moon. “Their potential presence on these bodies can be confirmed by future sample-return space missions,” he said.
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