The detection of some building blocks of life in the samples from asteroid Bennu brought to Earth could boost the theory of panspermia, which suggests that life exists throughout the universe and is distributed in different stellar systems by space dust, meteoroids, asteroids and comets.
The theory argues that life did not originate on Earth, but was seeded with life’s building blocks by these ‘carriers’ that crashed into our planet. Asteroid Bennu crashing into Earth is said to be a 1:2,700 probability. Meanwhile, NASA’s OSIRIS-Rex mission reached Bennu in 2020 and collected samples, which were stored in a protected capsule that was precision-dropped in the Utah desert in the US on September 24, 2023.
While initial studies indicated the presence of life’s building blocks in the samples, a clearer picture emerged when the findings were presented at the recent Lunar and Planetary Science Conference in Texas. The samples contain glycine, which is known as the simplest amino acid and an important ingredient of proteins, besides water-bearing minerals such as magnetite, sulphites, olivine and carbonates—considered to be essential components of life’s building blocks.
In December 2020, Japanese spacecraft Hayabusa-2 had returned to Earth after collecting samples from another near-Earth asteroid, Ryugu. In March 2023, scientists announced the presence of organic compounds such as uracil, among the components of ribonucleic acid or RNA, and vitamin B3 in those samples; they also contained carbonated liquid water in one crystal, which in turn contained salts and organic matter.
In 1871, Lord Kelvin—known for discoveries and inventions such as the absolute or Kelvin temperature scale, the second law of thermodynamics, telegraph cables and the galvanometer—had suggested at a meeting of the British Association for the Advancement of Science that the germs of life might have been brought to Earth by meteorites.
Almost a century later, the September 1969 explosion of a meteorite over Murchison town, north of Melbourne in Australia, revealed it carried 74 types of amino acids, eight of which were known to be involved in making earthly proteins. The latest findings, too, point to life-forming processes at work across the universe. It means extraterrestrial life likely exists and that life is not an erratic, exclusive domain of Earth. After all, we may not be as lonely as we think we are in this vast expanse of limitless space.