Extensive analysis of samples collected by the Japanese Hayabusa 2 spacecraft on the asteroid Ryugu has revealed that its surface is rich in molecules that form the basis of nucleotides, the ‘building blocks’ that makeup DNA and RNA: the molecules of life!
The spacecraft reached the asteroid on June 27, 2018, orbiting about 20 kilometers above the surface. During its 18-month mission to the asteroid, Hayabusa 2 descended to the surface twice, collecting two different types of samples, which landed in a super-protected capsule in the middle of the Australian desert on December 6, 2020.
Samples from Ryugu
Ryugu is an asteroid orbiting about 200 million kilometers from Earth, with a diameter of 448 meters and a shape resembling a spinning top. The purpose of JAXA’s mission was mainly to study the chemical composition and physical properties of the object, and also to make an artificial impact with a kind of bullet probe fired at full speed at the asteroid’s surface to collect samples of the subsurface.
The images taken by the spacecraft immediately showed that the surface of the asteroid was covered with boulders and pebbles of various shapes and sizes, but it was also immediately apparent that the surface was very clean, and in fact no high percentages of dust were detected.
At the end of December 2022, the first results of the observations of the samples were published, and they showed that Ryugu is composed of zinc, copper and carbonaceous chondrites, a chemically primitive material very similar to that found in the nebula from which the Solar System originated.
Organic molecules on Ryugu: Does life come from outer space?
During the first two months of 2023, samples from Ryugu were again studied, but this time the focus was on the organic analysis of the samples themselves.
The studies showed that the chemical composition of Ryugu is quite rich, as organic molecules, carbon, hydrogen, oxygen, nitrogen, and sulfur were observed.
However, there is a ‘problem’… All these molecules make up what scientists call the set of compounds that are fundamental to terrestrial-type life.
The fact that amino acids and molecules formed in the presence of liquid water have been found on Ryugu is a very important piece of information that allows scientists to review and update their knowledge of the origin of life on Earth.
According to Marco Ferrari, a researcher at the INAF in Rome, the molecules that are fundamental to the development of life probably originated in space, but this is neither a certainty nor a standard for resolving the delicate and complicated question of the origin of life in the cosmos.
Vitamins and RNA on the asteroid
Ryugu is a C-type asteroid, the most common type of asteroid in the main belt, so it was no real surprise to the scientists to find these organic molecules in the small pebbles they collected. In previous years, molecules of this type have been found in some asteroids that have fallen to Earth.
Small amounts of uracil, amino acids ,and various acids were found in the samples collected, while vitamin B3 was abundant.
Why should all this not immediately raise the possibility of life forms in space, or even on the asteroids themselves?
Scientists have found an answer to this, noting that the different concentrations of uracil, for example, depending on the different exposure of the asteroid’s surface to cosmic and UV radiation.
However, the discovery of such molecules in deep space could be direct evidence that the nitrogenous bases arrived on Earth thanks to the planet’s collision with carbonaceous asteroids, which acted as incubators for the prebiotic molecules during their interplanetary journey.
The search for the ‘building blocks’ of life continues
There is currently another spacecraft in deep space, but it is a NASA spacecraft, Osiris-Rex, which is studying the asteroid Bennu, also a C-type body. The data it will send back will provide a very important blueprint for comparing the two bodies and understanding whether the presence of organic molecules in deep space is really so common.