The organic material found in a few areas on the surface of dwarf planet Ceres is probably of exogenic origin. Impacting asteroids from the outer asteroid belt may have brought it with them.
In the journal AGU Advances, a group of researchers led by the Max Planck Institute for Solar System Research (MPS) in Germany presents the most comprehensive analysis to date of this mysterious material and its geological context. To this end, the team has, for the first time, used artificial intelligence to analyze observational data from NASA's Dawn spacecraft.
According to the study, the dwarf planet's unique cryovolcanism, in which salty brine rises from the body's interior to the surface, is not responsible for the organic deposits discovered so far. These new findings help to understand where and how habitable conditions could have arisen in the solar system.
Organic molecules are among the necessary inventory of life-friendly worlds. On Earth, the compounds of carbon, hydrogen and—in smaller quantities—other elements form the basic building blocks of all life. In recent years, researchers have found such molecules at great distances from the sun: on trans-Neptunian objects, comets, and far-away asteroids.
These bodies are thought to be largely unaltered remnants from the early days of the solar system. The building blocks of life may therefore have been part of their "basic configuration" from the very beginning and possibly reached the inner solar system only later.
Searching for Organics from Afar
Evidence of deposits of organic material had already been found during the early stages of the Dawn mission. The Dawn spacecraft reached Ceres in March 2015 and accompanied it for about three and a half years. During this time, the scientific camera system and the spectrometer on board scanned the entire surface of the dwarf planet.
Potential patches of organic material can be detected from the camera data: the brightness of the light reflected from these areas increases noticeably with increasing wavelength. The spectrometer splits the light into many more wavelengths than the camera and can therefore prove or disprove the presence of organics.
Unfortunately, remote data is not sufficient to identify individual types of molecules beyond doubt. However, it is certain that the discovered deposits consist of organic compounds that have a chain-like structure. Researchers refer to such molecules as aliphatic hydrocarbons.
The authors of the current study have now used artificial intelligence to comb the entire surface of the dwarf planet for traces of aliphatic organic molecules.
"Sites of such organic molecules are actually rare on Ceres, and devoid of any cryovolcanic signatures," says first author Ranjan Sarkar from the MPS, summarizing the results.
The vast majority of deposits can be found along the edge or near the large Ernutet crater in the northern hemisphere of the dwarf planet. Only three are located at a greater distance from it. Two patches were not previously known. A closer look at the geological structures at the locations of the organic material allows further conclusions.
At none of the deposits do we find evidence of current or past volcanic or tectonic activity: no trenches, canyons, volcanic domes or vents. Furthermore, there are no deep impact craters nearby," says Martin Hoffmann from MPS.
Impacts from Distant Neighbors
During the Dawn mission, Ceres had turned out to be an extraordinary, cryovolcanic world. Under its surface, a watery brine is hidden, which in some places has been seeping to the surface until recently.
"Of course, the first assumption is that Ceres's unique cryovolcanism has transported the organic material from the interior of the body to the surface," says Andreas Nathues from MPS, head of the camera team. "But our results show otherwise."
At the sites of cryovolcanic activity, there is no proof of organic matter. And where organic compounds have been reliably detected, there is no evidence of deep or surface activity.
The researchers therefore argue that the impact of one or more asteroids from the outer asteroid belt introduced the organic material. Computer simulations show that these bodies are among the ones that most frequently collided with Ceres. Since the not-too-distant neighbors do not pick up much speed, only little heat is generated upon impact. Organic compounds can survive these temperatures.
"Unfortunately, Dawn can't detect all types of organic compounds," Nathues points out. It is quite likely that building blocks of life were also formed in Ceres's underground ocean and perhaps even reached the surface—or are still doing so.
"However, the organic deposits that have been reliably detected by Dawn so far likely do not originate from Ceres itself," he explains. Nathues continues by saying that a future lander mission would be needed to detect organic material from the interior of Ceres.
Tables Summarizing Key Findings
| Finding | Description |
|---|---|
| Exogenic Origin | Organic materials likely delivered by impacting asteroids. |
| Cryovolcanism | No evidence that cryovolcanism is responsible for organic deposits. |
| Aliphatic Hydrocarbons | Deposits primarily consist of chain-like organic compounds. |
| AI Analysis | Artificial intelligence was utilized to search the surface for organics. |
| Geological Activity | No geological activity linked to sites of organic material. |
Future Research Directions
The next steps in Ceres research will focus on understanding the implications of these findings for planetary science and astrobiology.
- Continued Surveillance: Ongoing observations of Ceres will help determine if more organic materials are discovered in subsequent studies.
- Sample Return Missions: Future missions are planned to return samples from Ceres to provide definitive evidence about the origin of its organic material.
- In-Situ Analysis: Landers may be designed to explore the surface chemistry directly and provide more context about organic deposits.
Conclusion
The findings of organic materials on Ceres provide tantalizing evidence about the building blocks of life potentially being present not only on Earth but also on other celestial bodies. This research highlights the need for exploratory missions targeted to areas of known organic deposits and emphasizes the importance of understanding the formation and distribution of life's constituents in the universe.
For More Information, References and Resources
The following resources provide additional context and information on the findings related to Ceres:
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- 'Last Ice Area' in the Arctic Could Disappear Much Sooner
- Kitchen Experiments Shed Light on Mars's Volcanic Rootless Cones
Furthermore, find additional insights at Universetoday and stay updated on new developments in planetary science and astrobiology.
Max Planck Institute for Solar System Research - Official Website
Published on: January 27, 2025
