Earth-shattering! Did humans really come from outer space? Scientists have discovered RNA components on an asteroid
On the early morning of December 6, 2020, a visitor from outer space landed in the desert of northern South Australia. Staff from Japan’s JAXA Institute of Space and Astronautical Science retrieved two tubes of 5.4 grams of material from it.
On March 21, Japanese scientists announced that they had found one of the chemical components of RNA, uracil, and vitamin B3 in the two tubes of material, strongly indicating that these molecules with significance for the origin of life were usually formed in carbonaceous asteroids and delivered to early Earth.
Earth-shattering! Did humans really come from outer space? That’s what we’re asking ourselves.
The visitor that landed in the South Australian desert more than two years ago was the re-entry capsule of Hayabusa2, which was launched by Japan on December 3, 2014.
In February 2019, Hayabusa2 landed on Ryugu and fired a tantalum bullet to stir up surface material, collecting a tube of samples.
Later in April of that year, Hayabusa2 fired a larger copper projectile, blasting open Ryugu’s surface, and landed in July to collect a second tube of samples from beneath Ryugu’s surface.
After the samples were returned to Japan, astrochemists from Hokkaido University and Japan’s Agency for Marine-Earth Science and Technology began studying them. The scientists soaked the material in hot water and then performed liquid chromatography and high-resolution mass spectrometry analysis.
The results were astonishing. The scientists found two types of organic compounds essential for living organisms in both tubes of samples, including uracil, a component of RNA, and niacin, also known as vitamin B3, which is vital for metabolism. This strongly suggests that these molecules with significance for the origin of life were usually formed in carbonaceous asteroids and delivered to early Earth.
RNA is a molecule that exists in all living cells and is essential for the coding, regulation and activity of genes.
Uracil (U) is one of the four bases of RNA, which pairs with adenine (A). In DNA, uracil is replaced by thymine (T), which is uracil methylated.
Scientists have long suspected that comets, asteroids and meteorites that hit Earth 4.5 billion years ago when it was formed may have brought compounds necessary for life, paving the way for the first microbes.
Previously, scientists had found key organic molecules, including uracil and niacin, in carbon-rich meteorites found on Earth, but these meteorites could not rule out contamination from Earth’s organic matter.
And this time, uracil and niacin, as well as other organic molecules, including a series of amino acids, amines and carboxylic acids, were extracted from material directly from the asteroid, without Earth contamination, indicating that these biologically significant components of life do exist in extraterrestrial environments.
Scientists believe that as part of the asteroid, they may have indeed come to Earth in the early stages of its formation, and scientists suspect that they may have played a role before the origin of life.
These substances were found in two places on the asteroid Ryugu, only that the concentration on the surface was lower than that underground, meaning that the organic molecules on the surface were more easily degraded by high-energy particles in space.
So how did these substances form? Scientists believe that this may have been the result of chemical reactions triggered by starlight in the cold matter of interstellar space.
So far, these key organic substances related to life have only been found in material from one asteroid, Ryugu, while NASA’s OSIRIS-REx probe landed on another asteroid, Bennu, in October 2020 and collected up to 2 kilograms of samples, which will return to Earth on September 24 this year.
If similar organic matter is found in the samples returned by OSIRIS-REx, then it can be concluded that some of the key components of Earth’s life may be abundant in space and may have been the original source of life on Earth.
The United States and Japan have signed a cooperation agreement on sample exchange and research, and will exchange some samples and share software, data and analysis techniques. Perhaps we will soon see clearer conclusions.
Well, maybe we are all "aliens"?
This study was published in the journal Nature Communications on March 21.
Paper: https://www.nature.com/articles/s41467-023-36904-3