320 million kilometers from our planet, the Bénou asteroid keeps within it The secrets of the first moments of our solar system. The Osiris-Rex mission of NASA has just unraveled some, thanks to the analysis of the samples reported on Earth in September 2023. The results of the latter were published in two papers: one in the journal Nature Astronomy And the other in Nature.
Bénou and its 525 meters in diameter is actually a real natural laboratory of prebiotic chemistry (the study of chemical reactions which could lead to the formation of the first living molecules), in which The fundamental ingredients of life are indeed present. For NASA, it is a resounding success.
Bénou salts: witnesses of a primitive aqueous activity
NASA scientists who recovered these 120 g of dust collected on Bénou managed to identify, using electron microscopes, two particularly important minerals. The first, of halite, mineralogical name of the gem salt, or rock salt, which is mainly composed of sodium chloride (NACL). It is the same salt as the one we use daily in our kitchens.
The second element is sylvite, a mineral composed of potassium chloride (KCL), mainly used in the production of fertilizers because of its richness in potassium, An essential element for plant growth.
These salts, extremely rare in meteorites – they are only found in three specimens out of several hundred thousand – are precious indicators. Indeed, their presence is proof that Bénou has probably experienced interactions with liquid water in the past.
Water being an essential ingredient in life as we know it, its presence, even past, suggests that this asteroid could one day be an environment favorable to prebiotic chemistry. That is to say the chemistry which could lead to The emergence of life.
Researchers also have highlighted other precious mineralsinforming us about the story of Bénou and the chemical processes that took place there. Sodium carbonates, similar to those that are formed in terrestrial salty lakes, phosphates, compounds essential to energy storage in biological systems and sulfates/fluorides, which, on earth, play a role in many geochemical processes .
This mineralogical assembly indicates that the parent body of Bénou; himself fragment of a greater celestial body; experienced a period of aqueous activity, during which saline solutions evaporated, leaving behind them These characteristic deposits.
https://www.youtube.com/watch?v=42EWBQ3AFPA
A primitive soup rich in living molecules
In addition to these rare salts, Bénou was particularly rich in organic compoundscomplex molecules containing carbon, essential, too, to life and to many chemical processes. Among them, we can cite 14 of the 20 amino acids used by the earthly living. The latter are the constituent elements of proteins, fundamental molecules to life. The discovery of these organic molecules shows that the basic elements of life can therefore form in space and be present on celestial bodies like asteroids.
Another discovery: all of the five constitutive nucleobics of RNA and DNA. If we imagine that these are like long brick walls which contain all the information necessary to build and operate a living being. Nucleobics are the bricks that make up these walls. Finding them on the surface of Bénou means that the molecules which carry genetic information of all living beings, Also exist outside the earth.
A third compound that the sample contained: ammonia (NH3). Important nitrogen source, There is also an essential element in life. Nitrogen is a constitutive element of amino acids, proteins and nucleotide bases (the constituent elements of DNA and RNA).
The presence of these organic molecules suggests that similar processes may have occurred On other celestial bodiesthus increasing the possibility that life would exist elsewhere in the universe.
These very encouraging results will shed light on a new day Research on other celestial bodiesin particular Encelade, satellite of the great Saturn, and Ceres, dwarf planet of the asteroid belt. These two worlds are home to the oceans of brine (extremely salty water expanses) under their ice surface, in conditions potentially similar to those that have existed on the parent body of Bénou.
For now, Investigations continueand the work of scientists will focus on the precise dating of the fragmentation of the parent body of Bénou and on the traces of impacts recorded in the mineral composition of the samples. If no trace of life has been directly detected, This does not mean that research is in vain. These analyzes demonstrate that the chemical conditions necessary for the formation of molecules during the living already existed at the first moments of the solar system, there are more than 4.568 billion years. The other theory reinforced by these recent discoveries: Life could have an extraterrestrial origin (Panspermia). Asteroids or comets, like Bénou, may have brought these organic molecules on earth billions of years ago, thus contributing to the appearance of the first living organisms.
- The Bénou asteroid contains rare salts and organic compounds suggesting an old aqueous activity favorable to prebiotic chemistry.
- The samples revealed amino acids, nucleobics and ammonia, key elements for life, present outside the earth.
- These discoveries reinforce the idea that celestial bodies like Bénou have been able to sow the basics of life on earth and elsewhere in the universe.
