Organics on Ceres
NASA's Dawn spacecraft recently detected organic-rich areas on Ceres.
Scientists evaluated the geology of the regions to conclude that the organics are most likely native to the dwarf planet. Data from the spacecraft suggest that the interior of Ceres is the source of these organic materials, as opposed to arriving via impacting asteroids or comets, according to a paper published in the Feb. 17, 2017, issue of Science.
"This discovery of a locally high concentration of organics is intriguing, with broad implications for the astrobiology community," said Dr. Simone Marchi, a senior research scientist at Southwest Research Institute and one of the authors of the paper. "Ceres has evidence of ammonia-bearing hydrated minerals, water ice, carbonates, salts, and now organic materials. With this new finding Dawn has shown that Ceres contains key ingredients for life."
Ceres is believed to have originated about 4.5 billion years ago at the dawn of our solar system. Studying its organics can help explain the origin, evolution, and distribution of organic species across the solar system. Data from Dawn's visible and infrared mapping spectrometer show an unusually high concentration of organic matter close to the 50-km diameter Ernutet crater in the northern hemisphere of Ceres. The distribution and characteristics of the organics seem to preclude association with any single crater. The largest concentration appears to drape discontinuously across the southwest floor and rim of Ernutet and onto an older, highly degraded crater. Other organic-rich areas are scattered to the northwest. While other scientists looked at the distribution and spectra of the materials, Marchi focused on the geological settings.
"The overall region is heavily cratered and appears to be ancient; however, the rims of Ernutet crater appear to be relatively fresh," Marchi said. "The organic-rich areas include carbonate and ammoniated species, which are clearly Ceres' endogenous material, making it unlikely that the organics arrived via an external impactor."
Ceres shows clear signatures of pervasive hydrothermal activity, aqueous alteration and fluid mobility, so the organic-rich areas may be the result of internal processes. Dawn scientists will continue to study the dwarf planet to identify a viable method for transporting such material from the interior to the surface in the pattern observed.
These findings appear in the paper "Localized aliphatic organic material on the surface of Ceres" published in the Feb. 17, 2017, edition of the journal Science. Dawn's mission to Ceres and Vesta, the two most massive bodies in the asteroid belt, is managed by the Jet Propulsion Laboratory for NASA's Science Mission Directorate in Washington, D.C. Dawn is a project of the directorate's Discovery Program, managed by NASA's Marshall Space Flight Center in Huntsville, Ala. UCLA is responsible for overall Dawn mission science.