These first conclusions support the theory that asteroids brought organic matter to Earth for the birth of life on the planet.
The Ryugu asteroid contains a rich complement of organic molecules, according to initial analysis of a surface sample sent back to Earth by the Japanese Hayabusa2 spacecraft .
The discovery reinforces the idea that organic matter from space contributed to the inventory of chemical components necessary for life, reports NASA, which has participated in the research.
recipe for life
Organic molecules are the building blocks of all known terrestrial life and consist of a wide variety of compounds made up of carbon combined with hydrogen, oxygen, nitrogen, sulfur, and other atoms. However, organic molecules can also be made by chemical reactions that do not involve life, supporting the hypothesis that chemical reactions on asteroids can make some of the ingredients of life.
The science of prebiotic chemistry tries to discover the compounds and reactions that could have given rise to life, and among the organic prebiotics found in the sample were various types of amino acids. Certain amino acids are widely used by terrestrial life as building blocks for proteins. Proteins are essential to life, as they are used to make enzymes that speed up or regulate chemical reactions and to make microscopic to large structures such as hair and muscle.
The sample also contained many types of organic compounds that form in the presence of liquid water, such as aliphatic amines, carboxylic acids, polycyclic aromatic hydrocarbons, and nitrogen-containing heterocyclic compounds.
“The presence of prebiotic molecules on the asteroid’s surface despite its harsh environment caused by solar heating and ultraviolet irradiation, as well as cosmic ray irradiation under high vacuum conditions, suggests that Ryugu’s uppermost surface grains have the potential to protect organic molecules,” says Hiroshi Naraoka of Kyushu University, Fukuoka, Japan. “These molecules can be transported throughout the solar system, potentially dispersing as interplanetary dust particles after being ejected from the asteroid’s uppermost layer by impacts or other causes.” Naraoka is lead author of a paper on this research now published in Science.
“So far, Ryugu ‘s amino acid results are largely consistent with what has been observed in certain types of carbon-rich (carbonaceous) meteorites that have been exposed to the greatest amount of water in space,” says Jason Dworkin of the Center. Goddard of NASA Space Flight in Greenbelt, Maryland, a co-author of the article.
“However, the sugars and nucleobases (components of DNA and RNA) that have been discovered in some carbon-rich meteorites have not yet been identified in the samples returned by Ryugu ,” says Daniel Glavin of NASA’s Goddard Center. and co-author of the article. “It is possible that these compounds are present in the Ryugu asteroid , but below our analytical detection limits, given the relatively small mass of the sample available for study.”
a unique case
The samples were collected by the Hayabusa2 spacecraft on February 22, 2019 , and delivered to Earth on December 6, 2020. They were collected in Japan in July 2021 and analyzed at Goddard in fall 2021. A very small amount of sample (30 milligrams) for the international soluble organic analysis team. The sample was extracted (like tea) in many different solvents in Japan and analyzed in laboratories in Japan, Goddard and Europe using a wide range of forensic laboratory-like machines.
This work is the first organic analysis of the Ryugu sample , and the samples will be studied for years to come. “We will make a direct comparison of the Ryugu samples and the sample from the asteroid Bennu when NASA’s OSIRIS-REx mission returns it to Earth in 2023 ,” Dworkin said. “OSIRIS-REx is expected to return much more sample mass from Bennu and will provide another important opportunity to search for trace organic building blocks of life on a carbon-rich asteroid .” (Europe Press)