The Dawn spacecraft has detected organic compounds on Ceres, a dwarf planet in the asteroid belt between Mars and Jupiter. The findings are reported today in Science.
Organic compounds are the building blocks of life on Earth. Today’s findings, combined with the fact that Ceres has abundant water and maybe even internal heating, suggest that “that primitive life could have developed on Ceres,” notes Michael Küppers, a planetary scientist with the European Space Agency, in a commentary in Science. Küppers wasn’t involved in the research published today. It’s important to note, however, that no evidence of such life has actually been found—even if Ceres has everything it would need in order to house a life form, there still might not be anybody home.
An international team of researchers detected the organics using the Visible and InfraRed Mapping Spectrometer on the Dawn spacecraft, which has been orbiting Ceres since 2015.
The spectrometer investigated the area around a crater called Ernutet, and found compounds that contain methyl and methylene groups. Although the exact identity of the compounds is unclear, they are likely similar to the hydrocarbon chains that make up tar-like minerals such as asphaltite and kerite.
It appears these organic molecules were made on Ceres, instead of being delivered by other space rocks crashing into the dwarf planet. The heat of such an impact would have destroyed the organics, and their distribution suggests they didn’t come from an impact. Instead, the researchers suggest they may have been formed inside Ceres. However, scientists are still investigating how the molecules could have formed and migrated up to the surface.
This is the first time organic molecules have been definitively detected in the asteroid belt. The findings, together with the discoveries from Europe’s Rosetta mission to Comet 67P/Churyumov-Gerasimenko, “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,” writes Küppers.
If organics and water ice do litter the asteroid belt, it could explain how Earth got its water and the building blocks of life. Planetary scientists think that during the early days of the solar system, Earth was too hot for those things to develop, and may instead have received the molecules from incoming asteroids and comets.
Ceres has only a very thin atmosphere, and the temperature on its surface ranges from minus 100 to minus 225 degrees Fahrenheit. But below its surface, it harbors a vast amount of water ice—possibly even an ocean—and may still have some internal heating leftover from the days of its formation. With ammonia-bearing minerals, salts, and now organic materials, Ceres contains many of the ingredients necessary for life as we know it to evolve.
“Ceres joins Mars and several satellites of the giant planets in the list of locations in the solar system that may harbor life,” Küppers writes.
Although there’s still a lot to learn about the exact nature of the Ceres’ organics and whether it really could harbor an inner ocean, Küppers told Popular Science that, “In principle life could exist on Ceres today.” And it may even be easier to search for it on Ceres than on places like Europa.
“It’s closer to Earth and a spacecraft does not suffer the high radiation levels that it experiences in the environment of the outer planets. Admittedly, in all cases it is challenging to search for life that, if it exists, is expected to be several kilometers below the surface.”