29.01.2025

Surface of dwarf planet Ceres. The sites of organic material are shown as or in red boxes. The vast majority of sites are found near the Ernutet crater in the northern hemisphere. Credit: MPS.

Dwarf planet Ceres has a smattering of organic material on its surface. New research suggests these organic compounds came from impacting asteroids from the outer asteroid belt.

Ceres was the first asteroid to be discovered in 1801. It is the largest object in the asteroid belt which sits between the orbits of Mars and Jupiter. Ceres is about 950km across, making it 1/13th the width of Earth and less than half the size of Pluto.

In 2015, NASA’s Dawn spacecraft took up position in orbit above Ceres. In 2017, data from Dawn confirmed that the dwarf planet has organic compounds – carbon-based molecules. Dawn cannot identify the exact organic compounds present on Ceres.

The discovery raised the possibility that early life developed on Ceres.

The new study, published in the journal AGU Advances, sought to answer the question: where did the molecules come from?

Previous theories suggested that the dwarf planet’s unique cryovolcanism was behind the organic compounds. This process sees a salty brine rise from the body’s interior to the surface.

The new research looked for previously unidentified deposits of organic material on Ceres.

The authors say their data does not support the theory that cryovolcanism is responsible for the presence of organic molecules on Ceres. The most likely source, therefore, is other asteroids from the outer asteroid belt.

The majority of the organic material was found along the edge of or near the large Ernutet crater in the northern hemisphere.

“Sites of such organic molecules are actually rare on Ceres, and devoid of any cryovolcanic signatures,” says first author Ranjan Sarkar from the Max Planck Institute for Solar System Research (MPS) in Germany.

Computer simulations showed that the most common objects to impact with Ceres – and therefore the likely carriers of the organic material – are asteroids from the outer asteroid belt.

Because these objects are not too far away, they wouldn’t have picked up much speed. This means there was not much heat generated in the impacts, allowing organic compounds to survive. This dispels previous notions that impacts would have been too hot for organic material to be transported to Ceres in this way.

Quelle: COSMOS