NASA’s Dawn spacecraft, which has been orbiting dwarf planet Ceres for nearly two years, has detected organic molecules, the building blocks of life, on Ceres’ surface.
Dawn’s visible and infrared mapping spectrometer instrument found the organic molecules in two locations–the 385-square mile (1,000 square km) region around Ceres’ Ernutet Crater and inside the much smaller 250-mile (400 km) Inamahari Crater.
Ernutet Crater is about 33 miles (53 km) wide.
Because Dawn searched for organic molecules only in the latitudes between 60 degrees north and 60 degrees south, there could be other places outside this area that also contain organics.
“We cannot exclude that there are other locations rich in organics not sampled by the survey, or below the detection limit,” Maria Cristina De Sanctis of the Institute for Space Astrophysics and Space Planetology in Rome told the website Space.com.
While Dawn’s instruments can determine the signatures of these organic molecules, as these signatures resemble tar-like substances kerite and asphaltite, they do not have the capability of identifying the molecules.
However, scientists can tell the organic molecules are native to Ceres and were not brought there by impacting comets or asteroids.
“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,” said Simone Marchi of Boulder, Colorado’s Southwest Research Institute.
An impact would have produced extreme heat that likely would have destroyed the organic material.
Ceres may still have an internal heat source dating back to its formation, meaning it could harbor a subsurface ocean that could possibly host microbial life, noted Michael Kuppers of the European Space Astronomy Centre near Madrid, Spain.
Kuppers did not take part in this study.
“It joins Mars and several satellites of the giant planets in the list of locations in the solar system that may harbor life,” Kuppers said.
Data returned by Dawn helped scientists locate water ice beneath Ceres’ surface.
One possible explanation for the organic molecules is that they formed through reactions with hot water. “Ceres shows clear signatures of pervasive hydrothermal activity and aqueous alteration,” De Sanctis and her team wrote in a paper on their findings published in the journal Science.
She compared Ceres to Jupiter’s moon Europa and Saturn’s moon Enceladus, both of which are believed to harbor subsurface oceans.
“We see compounds on the surface of Ceres-like the ones detected in the plume of Enceladus,” she added.
While scientists have not yet found direct evidence of an underground ocean on Ceres, if one exists, its temperatures would be warmer than those of oceans on Europa and Enceladus and therefore possibly more hospitable for life.