The Largest Object in the Asteroid Belt May Have Hosted Life! – Future

The Dawn spacecraft’s flyby of Ceres, the largest object in the asteroid belt between Mars and Jupiter, made it possible to detect the presence of complex organic molecules there. Scientists know that the dwarf planet once hosted an ocean of liquid water and believe it once had conditions conducive to the emergence of life. The origin of these organic molecules on the surface of Ceres is the subject of much research.

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At the border between the inner solar system and the outer solar system, between the orbits of Mars and Jupiter, billions of small celestial bodies revolve, the size of which can vary from millimeters to kilometers. They form the main belt, or asteroid belt, which was formed about 4.6 billion years ago by asteroids that did not coalesce to form planets. But one object in the main belt stands out from the others, especially because of its size: it is Ceres, the only dwarf planet in the main belt. With a radius of about 476 kilometers, Ceres alone represents almost a third of the mass of the main belt. With a large amount of water ice on its surface, it is also the only spherical object in the asteroid belt.

The dwarf planet, discovered in 1801, has been the subject of much recent study as scientists believe it is a protoplanet whose properties have remained unchanged since the formation of our solar system. Scientists’ curiosity about this celestial body has been further piqued since the discovery of the presence of hydrated materials on its surface, suggesting the presence of a significant amount of water in its interior and a possible ocean beneath the Earth.

Insightful in situ observations

In order to uncover the secrets of the dwarf planet, the American space agency NASA launched its Dawn space probe in 2007 to closely observe Ceres and the asteroid Vesta, which is also developing in the asteroid belt. Equipped in particular with a spectrometer that makes it possible to remotely determine the chemical composition of the observed surfaces, the main objective of the probe was to contribute to the understanding of the processes involved in the formation of the solar system.

After its observations of the asteroid Vesta, the probe flew towards Ceres, around which it was in orbit in 2015. And the observations of the dwarf planet led to surprising results: the probe discovered the presence of complex organic molecules on the surface of Ceres. Combined with the idea that the dwarf planet could host a marine world, these results suggest that Ceres once harbored the necessary ingredients for the emergence of life as we know it. The Dawn probe is no longer active today and has become a “passive” satellite of Ceres.

The origin of these organic compounds is still debated

The organic compounds detected on the surface of Ceres are called aliphatic: they are hydrocarbons (consisting only of hydrogen and carbon atoms) whose carbon chains have linear structures (e.g. methane). Since their discovery in 2017, the reasons for their presence on the dwarf planet have been the subject of much research and hypotheses, generally leading to two distinct schools.

Some scientists believe that these compounds arrived at Ceres through impacts from comets or other celestial bodies rich in organic compounds, while others suggest that these compounds were formed by the alteration of the originally present compounds by exposure to salt water. Given the numerous impacts that the dwarf planet has suffered (and continues to suffer), the evolution of these organic molecules on the surface of Ceres is very likely closely linked to the almost ubiquitous impacts that have shaped its surface, especially since the first organic compounds were detected were near an impact crater.

The result of multiple processes?

However, a recent study presented at the Geological Society of America (GSA) on October 17 tends to show that the appearance of these organic molecules is actually the result of several different processes and phenomena that mix the two main hypotheses previously put forward. To determine the origin of these organic compounds, the authors combined the data collected by the spectrometer and those measured by the camera on board the probe, allowing them to create an accurate map of the presence of organic compounds on the surface of the dwarf planet. At the same time, they simulated the impact conditions typical of Ceres with impact speeds between 2 and 6 km/s and impact angles between 15 and 90 degrees to the horizontal.

Their results thus indicate a strong spatial correlation between the presence of organic compounds and the location of impact structures, as well as between the presence of organic compounds and the presence of minerals such as carbonates, indicating the presence of water. Although the origin of these compounds is still poorly understood, scientists are certain that a significant part is of endogenous origin: they estimate that these organic compounds could have formed on Ceres, probably thanks to the presence of water. This conclusion suggests the plausible existence of a large reservoir of organic compounds inside the dwarf planet, motivating its interest in the search for extraterrestrial life.