(CNN) Organic molecules have been found in samples collected by Japan’s Hayabusa2 mission from the near-Earth asteroid Ryugu.
“When the researchers analyzed the samples, collected from two different locations on the asteroid, they found uracil, one of the building blocks of RNA, as well as vitamin B3, or niacin (a key cofactor for in metabolism in living organisms).
Uracil is a nucleobase, or a nitrogen-containing compound. It is one of the five nucleobases in DNA and RNA, the proteins and molecules that contain the genetic information and instructions essential for the cells of living organisms.
A study detailing the findings was published Tuesday in the journal Communication in Nature.
Ryugu is a carbon-rich, diamond-shaped asteroid measuring about 3,000 feet (1 kilometer) in diameter. Hayabusa2 is the first mission to return a subsurface sample from an asteroid to Earth.
The Japanese Aerospace Exploration Agency’s mission collected a sample from the asteroid’s surface in February 2019, after fired a copper “bullet” at the asteroid to create a 33-foot (10-meter) wide crater effect. A sample was collected from this crater in July 2019. Hayabusa2 then flew by Earth and dropped the sample in Australia in December 2020.
In earlier tests, researchers found amino acids and other molecules in Ryugu’s samples, while uracil and niacin were also found in meteorites that landed on Earth.
“Scientists have previously found nucleobases and vitamins in some carbon-rich meteorites, but there is always the question of contamination through exposure to the Earth’s atmosphere,” said lead study author Yasuhiro Oba, associate professor at Hokkaido University in Japan, in a statement. “Because the Hayabusa2 spacecraft collected two samples directly from asteroid Ryugu and delivered them to Earth in sealed capsules, the contamination could be eliminated.”
Building blocks of life in space
The researchers discovered the molecules when they soaked the particles collected from Ryugu in hot water and analyzed the results using different observation methods, such as liquid chromatography and mass spectrometry.
The scientists worked with samples collected from two different sites on the near-Earth asteroid Ryugu.
Then, the team found the signatures of uracil, niacin and other nitrogen-containing organic compounds.
“Other biological molecules were also found in the sample, including a selection of amino acids, amines and carboxylic acids, found in proteins and metabolism, respectively,” said Oba.
Together, the findings from Ryugu’s samples so far add to the growing evidence that the building blocks of life originated in space and were originally delivered to Earth billions of years ago by meteorites.
The molecules were likely originally formed by photochemical reactions in ice in outer space before our solar system existed, Oba said.
Further study of asteroid composition
The concentrations of the molecules in the two samples are different, but this is likely due to exposure to the harsh environment of space. It is possible that Ryugu was once part of a larger celestial body, such as a comet, before it was broken into fragments by collisions with other interstellar objects.
“There is no doubt that biologically important molecules such as amino acids and nucleobase(s) in asteroids/meteorites have been donated to Earth,” Oba said. “In particular, we expect that they may play a role for prebiotic evolution on the early Earth.”
It’s also possible that as space rocks crash into other planets in our solar system, they may be carrying some of the same building blocks of life.
“I cannot say that the presence of such substances directly leads to the emergence / existence of extraterrestrial life, but at least their components such as amino acids and nucleobases can be present everywhere in space,” said Oba.
Now, researchers want to know how common these molecules are in asteroids. Fortunately, a sample from another named asteroid Bennu will be delivered to Earth in September of NASA’s Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer, or OSIRIS-REx spacecraft.
“The discovery of uracil in samples from Ryugu gives strength to current theories about the origin of nucleobases on the early Earth,” said Oba. “NASA’s OSIRIS-REx mission will return samples from asteroid Bennu this year, and a comparative study of the composition of these asteroids will provide additional data to build on these theories.”
