2025-08-20 NASA
Dwarf planet Ceres is shown in these enhanced-color renderings that use images from NASA’s Dawn mission. New thermal and chemicals models that rely on the mission’s data indicate Ceres may have long ago had conditions suitable for life. NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
＜関連情報＞
- https://www.nasa.gov/missions/dawn/nasa-ceres-may-have-had-long-standing-energy-to-fuel-habitability/
- https://www.science.org/doi/10.1126/sciadv.adt3283
- https://www.science.org/doi/10.1126/science.aal4765
- https://www.science.org/doi/10.1126/science.aaj2305
コアの変成作用が中規模海洋世界の動的居住可能性を制御する——セレスの事例 Core metamorphism controls the dynamic habitability of mid-sized ocean worlds—The case of Ceres
Samuel W. Courville, Julie C. Castillo-Rogez, Mohit Melwani Daswani, Jordyn Robare, and Joseph G. O’Rourke
Science Advances Published:20 Aug 2025
DOI:https://doi.org/10.1126/sciadv.adt3283
Abstract
Ceres’s surface mineralogy and density structure indicate an aqueous past. Observations from the Dawn mission revealed that Ceres likely hosted a global subsurface ocean in its early history, which was the site of pervasive aqueous alteration of accreted material. Subsurface environmental constraints inferred from Ceres’s surface mineralogy, combined with Ceres’s high abundance of carbon, suggest that the dwarf planet may have been habitable for microbial life. We present a coupled chemical and thermal evolution model tracking Ceres’s interior aqueous environment through time. If the rocky interior reached ≳550 K, then fluids released by rock metamorphism would have promoted conditions favorable for habitability by introducing redox disequilibrium into the ocean, a source of chemical energy for chemotrophs. We find that this period would have been between ~0.5 and 2 billion years after Ceres’s formation. Since then, Ceres’s ocean has likely become a cold, concentrated brine with fewer sources of energy, making it less likely to be habitable at present.
準惑星セレスと生命の構成要素 ドーン宇宙探査機が、セレスに有機物質と水氷の存在を示す証拠を発見 Dwarf planet Ceres and the ingredients of life The Dawn spacecraft finds evidence for organic material and water ice on Ceres
Michael Küppers
Science Published:17 Feb 2017
DOI:https://doi.org/10.1126/science.aal4765
Abstract
A fundamental question in the evolution of the early Earth is the origin of the oceans and of some of the organic molecules that were required for the formation of life. Earth formed in the protoplanetary disk, a mixture of gas and dust. At the location of Earth, temperatures were too high for water vapor and some more volatile organic components to condense. This led to the idea that those materials may have been delivered to Earth by asteroids and/or comets from the outer solar system. Recent spacecraft studies of Comet 67P/Churyumov-Gerasimenko with Rosetta (1, 2), and of Ceres on page 719 of this issue by De Sanctis et al. (3) and by Prettyman et al. (4) with the Dawn space probe, provide evidence that complex organic molecules and even amino acids are ubiquitous on small bodies in the solar system and that water ice is abundant in the asteroid belt.
セレスの表面に見られる局所的な脂肪族有機物質 Localized aliphatic organic material on the surface of Ceres
M. C. De Sanctis, E. Ammannito, H. Y. McSween, A. Raponi, […] , and C. T. Russell
Science Published:17 Feb 2017
DOI:https://doi.org/10.1126/science.aaj2305
Organic compounds detected on Ceres
Water and organic molecules were delivered to the early Earth by the impacts of comets and asteroids. De Sanctis et al. examined infrared spectra taken by the Dawn spacecraft as it orbited Ceres, the largest object in the asteroid belt (see the Perspective by Küppers). In some small patches on the surface, they detected absorption bands characteristic of aliphatic organic compounds. The authors ruled out an external origin, such as an impact, suggesting that the material must have formed on Ceres. Together with other compounds detected previously, this supports the existence of a complex prebiotic chemistry at some point in Ceres’ history.
Abstract
Organic compounds occur in some chondritic meteorites, and their signatures on solar system bodies have been sought for decades. Spectral signatures of organics have not been unambiguously identified on the surfaces of asteroids, whereas they have been detected on cometary nuclei. Data returned by the Visible and InfraRed Mapping Spectrometer on board the Dawn spacecraft show a clear detection of an organic absorption feature at 3.4 micrometers on dwarf planet Ceres. This signature is characteristic of aliphatic organic matter and is mainly localized on a broad region of ~1000 square kilometers close to the ~50-kilometer Ernutet crater. The combined presence on Ceres of ammonia-bearing hydrated minerals, water ice, carbonates, salts, and organic material indicates a very complex chemical environment, suggesting favorable environments to prebiotic chemistry.
