Equipped with an ion engine for interplanetary travel, the Dawn probe was launched in 2007 by NASA to “ boldly go where no man has gone before ! » in this case going into orbit first around the asteroid Vesta in 2011 and then CeresCeres from 2015 to 2018.
The data provided by the probe’s instruments concerning this dwarf planet which is also the largest asteroid in our Solar System (with a radius of 470 kilometers) surprised planetologists and even exobiologists. When he discovered it in 1801, theastronomerastronomer Italian Giuseppe Piazzi certainly could not have foreseen that his modern colleagues would see in Ceres both a embryoembryo planet and a protoplanet, vestiges of those which abounded in the protoplanetary diskprotoplanetary disk where the planets we know today in our Solar System were born.
These same colleagues a few decades ago would perhaps be surprised to learn that we have even imagined for some time, always based on the observations of DawnDawnthat Ceres was perhaps in the distant past an oceanic world as is currently the case with Europa and Enceladus – the MondayMonday of JupiterJupiter et SaturnSaturn – well almost rather with a muddy global ocean. Ceres appears to contain a lot of water, perhaps already in the form of ice mixed with rock and originating from its ancient ocean, perhaps also constituting a frozen envelope around a remnant liquidliquid of this ocean.
A large brine tank
However, it turns out that in recent years, by probing Dawn data, we have found more and more traces of moleculesmolecules surface organic matter occupying certain regions of Ceres. We could therefore imagine that life, or at least one chemistrychemistry prebioticprebiotic complex similar to that which must have existed on the primitive Earth more than 4 billion years ago, has left traces that could be discovered by sending robotic or even manned missions to the surface of Ceres in the decades to come.
What is certain is that the density of the protoplanet is close to that of ice and that in 2020, planetologists had discovered in Dawn data signs of the existence inside Ceres of a vast tank brinebrine and showed the presence of chloride sodiumsodium hydrated on the largest bright area in the floor of Occator crater.
Today, a team of researchers led by members of theInstitute of Astrophysics of Andalusia (IAA-CSIC) published an article in The Planetary Science Journal where, according to an accompanying IAA press release, it is explained that eleven new regions suggesting the existence of an internal reservoir of materialsmaterials organics in the dwarf planet have been identified.
Biological processes in early Ceres?
Before this work, we tended to think that the traces of organic matter detected on the surface of Ceres in 2017 could simply be the impact remains of cometscomets or small celestial bodies whose composition is similar to those of the chondriteschondrites carbon deposits found on Earth, such as that of the meteoritemeteorite by Murchison.
But new analyzes about these traces near the Ernutet crater in thenorthern hemispherenorthern hemisphere of Ceres suggest that it is quite different and that organic matter was formed inside Ceres and that it was initially stored in a reservoir protected from solar radiationsolar radiation ; this is explained in the press release in which Juan Luis Rizos, researcher at the Institute ofastrophysicsastrophysics of Andalusia and lead author of the study states that “ the importance of this discovery lies in the fact that, if it concerns materials endogenousendogenousit would confirm the existence of sources ofinternal energyinternal energy that could support biological processes ».
The researchers reached this conclusion by studying in particular a region between the Urvara and Yalode basins where we found that organic compounds are distributed within a geological unit formed by the ejection of material during impacts. who created these basins.
« These impacts were the most violent Ceres has ever experienced, so the material must have come from deeper regions than material ejected from other basins or craters. If the presence of organic compounds is confirmed, their origin leaves little doubt that these compounds are endogenous materials », specifies Rizos.
A presentation of the results of the IAA’s work. © Institute of Astrophysics of Andalusia (IAA-CSIC)
The reasoning is all the more convincing since another team has just published in Science the result of laboratory experiments on Earth which show that organic compounds of the kind detected on Ceres degrade more quickly, under the effect of solar radiation in interplanetary space and on the surface of bodies like Ceres, than that we previously thought. Given the quantities detected, they must come from significant reservoirs beneath the surface of Ceres.
By Hervé Cottin, astrochemist, university professor, LISA, University of Paris Est Créteil/University of Paris/CNRS. Are we alone in the universe? You may have already asked yourself this question? We can find answers in films, literature or science fiction comics and our imagination is populated by extraterrestrial creatures! But what does science say about this? The AstrobioEducation site invites you to discover exobiology, an interdisciplinary science which aims to study the origin of life and its research elsewhere in the Universe. Through an educational journey divided into 12 stages, researchers from different disciplines will help you understand how science works to answer the fascinating questions of the origins of life and its research elsewhere than on Earth. © French Society of Exobiology
This of course remains to be demonstrated, but as Rizos always explains, “ Ceres will play a key role in future space exploration. Its water, present in ice and perhaps liquid form below the surface, makes it an intriguing location for resource exploration. In the context of space colonization, Ceres could serve as a stopover or resource base for future missions to Mars or beyond ».
