Cradle of life?
So what do we make of these confusing observations, which come from the visible and infrared mapping spectrometer on the Dawn spacecraft?
Ceres, seen from 21,000km. Source: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
The authors argue that the organics are unlikely to come from the impact of another body with Ceres, because the specific nature of the organic compounds that have been detected implies they would have been degraded or destroyed by the high temperatures of the collision. It is also likely that collision with another body would have mixed any organics with the surface material, not leaving them concentrated in the way that they are.
So instead the authors infer that the compounds are probably indigenous to Ceres. This is strengthened by the fact that the molecules are found together with carbonates and clays containing ammonia. These have been observed in many regions of Ceres, and are believed to be produced by hydrothermal processes (reactions involving heated water) on the dwarf planet – something we know can also produce organic material on Earth.
Indeed, the data show that carbonates and clays are higher in abundance around Ernutet than the surrounding landscape. Hydrothermal processes, such as those that occur at hot springs on Earth, might have been active in Ceres’ past, when the asteroid was warmer at depth than it is now, leading to the formation of the organics. But this also means that the mechanism that brought the minerals to the surface at Ernutet – and nowhere else – is unknown.
The combination of hot water and organic material is extremely exciting. Once you have an environment conducive to the production of organic materials – especially one that also contains the nitrogen-bearing clay minerals which are known to catalyse other reactions – it may not be a step too far to posit that Ceres had (and maybe still has) all the ingredients essential for formation of the chemicals that, on Earth, eventually led to the origin of life.
Ernutet is the Egyptian goddess of fertility or nourishment. Wouldn’t it be wonderful if finding organic molecules in a crater named after her was the first indication of a non-terrestrial cradle of life?