Asteroid Ryugu is rich in organic molecules that could be building blocks of life. The discovery was made when scientists took a first look at a sample collected by the Hayabusa2 spacecraft.
Japan Aerospace Exploration Agency‘s (JAXA) Hayabusa2 spacecraft collected samples from Ryugu, located 347 million kilometers from Earth, in February 2019. The samples were then returned to Earth in December 2020 and extracted in Japan in 2021. A small amount, 30 milligrams of that sample, was then analyzed by the international organic analysis team at NASA‘s Goddard Space Flight Center.
The sample collected from Ryugu contains several so-called prebiotic organic substances, including different types of amino acids that living beings use to build essential proteins. These proteins are essential for regulating chemical reactions and forming structures like hair and muscles. The molecules found can also be created by non-living processes, such as chemical reactions that can occur on asteroids.
Ingredients for living beings
The results add further credibility to the theory that the basic ingredients needed to kick-start the development of life on Earth may have arrived from space. “The presence of prebiotic molecules on the asteroid’s surface suggests that the uppermost surface grains of Ryugu have the potential to protect organic molecules. Despite the hostile environment caused by solar heating, ultraviolet irradiation, and cosmic ray irradiation” said the lead author of the research published in Science (rif.), astrobiologist Hiroshi Naraoka.
“These molecules can be transported throughout the solar system, potentially dispersing as interplanetary dust particles after being expelled from the asteroid’s top layer by impacts or other causes”. The term organic molecules describes a wide range of compounds based on carbon coupled with hydrogen, oxygen, nitrogen, and sulfur. These five elements are the building blocks of all forms of life on our planet.
All compounds that derive from these five atoms can be created by chemical reactions that do not involve living beings. This means that chemical processes inside asteroids can create ingredients for life. The search for these chemical processes that could have led to the emergence of life on Earth is known as prebiotic chemistry.
The first organic analysis of an asteroid
In the Ryugu sample rich in organic molecules, prebiotic molecules that form in the presence of liquid water were also found. Water is essential for life and essential for forming aliphatic amines, carboxylic acids, polycyclic aromatic hydrocarbons, and heterocyclic compounds containing nitrogen.
“So far, Ryugu’s amino acid results are mostly consistent with what has been seen in carbon-rich meteorites exposed to water in space” said co-author Jason Dworkin. The Ryugu sample lacks sugars and DNA and RNA components that have been discovered in other carbon-rich asteroids. The team suspects that these compounds are present in Ryugu but are below the detection limits given the small mass of the sample examined for this research.
This new research represents the first organic analysis of the Ryugu sample that will be studied for many years to come. Future investigations will include comparing the Ryugu sample with samples from the Bennu asteroid collected in 2020. “We will make a direct comparison between the Ryugu and Bennu asteroid samples when NASA’s OSIRIS-REx mission returns them to Earth in 2023″ Dworkin said. “OSIRIS-REx is expected to return a much larger sample mass from Bennu. This will provide another important opportunity to search for traces of organic building blocks of life on a carbon-rich asteroid“.