SwRI Scientists Dig into the Origin of Organics on Ceres

SwRI scientists are studying the geology associated with the organic-rich areas on Ceres. Dawn spacecraft data show a region around the Ernutet crater where organic concentrations have been discovered (background image). The color coding shows the surface concentration of organics, as inferred from the visible and near infrared spectrometer. The inset shows a higher resolution enhanced color image of the Ernutet crater acquired by Dawn’s framing camera. Regions in red indicate higher concentration of organics. (Credit: NASA/JPL-Caltech/UCLA/ASI/INAF/MPS/DLR/IDA)

SAN ANTONIO, October 18, 2017 (SwRI PR) – Since NASA’s Dawn spacecraft detected localized organic-rich material on Ceres, Southwest Research Institute (SwRI) has been digging into the data to explore different scenarios for its origin. After considering the viability of comet or asteroid delivery, the preponderance of evidence suggests the organics are most likely native to Ceres.

“The discovery of a locally high concentration of organics close to the Ernutet crater poses an interesting conundrum,” said Dr. Simone Marchi, a principal scientist at SwRI. He is discussing his team findings today at a press conference at the American Astronomical Society’s 49th Division for Planetary Sciences Meeting in Provo. “Was the organic material delivered to Ceres after its formation? Or was it synthesized and/or concentrated in a specific location on Ceres via internal processes? Both scenarios have shortfalls, so we may be missing a critical piece of the puzzle.”

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. The very location of Ceres at the boundary between the inner and outer solar system and its intriguing composition characterized by clays, sodium- and ammonium-carbonates, suggest a very complex chemical evolution. The role of organics in this evolution is not fully understood, but has important astrobiological implications.

“Earlier research that focused on the geology of the organic-rich region on Ceres were inconclusive about their origin,” Marchi said. “Recently, we more fully investigated the viability of organics arriving via an asteroid or comet impact.”

Scientists explored a range of impact parameters, such as impactor sizes and velocities, using iSALE shock physics code simulations. These models indicated that comet-like projectiles with relatively high impact velocities would lose almost all of their organics due to shock compression. Impacting asteroids, with lower incident velocities, can retain between 20 and 30 percent of their pre-impact organic material during delivery, especially for small impactors at oblique impact angles. However, the localized spatial distribution of organics on Ceres seems difficult to reconcile with delivery from small main belt asteroids.

“These findings indicate that the organics are likely to be native to Ceres,” Marchi said.

Dawn’s mission to Ceres and Vesta, the two most massive bodies in the main 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, Alabama. UCLA is responsible for overall Dawn mission science.

  • Eric Copenhaver

    So…. if the findings lead to the preliminary conclusion that the organics are ‘native’ to Ceres, it follows that Ceres produced them, in some as-yet-undetermined way, or that the organics have been present since the formation of Ceres, roughly 4.5 billions years ago. Have I got that right?

    Regarding that 4.5 billion year formation date… anybody around here ever look at some way-out-there sci-fi-meets-archaeology books from the Seventies called “The Earth Chronicles”? Seems the author, who is thoroughly discredited nowadays, has a mechanism that explains the presence of organics on a main belt asteroid. I’ll save you the suspense (assuming you haven’t already heard this one before… which I KNOW some of you have heard before): the main belt itself is the result of… planetary collisions! Namely, the collision of the proto-Earth with another planetary body.

    The presence of organics on Ceres is to be expected, as the main belt objects are the remains, the ‘coronal ejecta’, of an inter-planetary collision involving the only place we now recognize as harboring continuous organic processes- the Earth.
    Ceres may be like a fingernail scraping from mamma Earth. And we can expect to find other such “DNA” of our homeworld, in the main belt, and possibly in other locations throughout the solar system, especially its more extended reaches.

  • duheagle

    Don’t confuse “organics” with life. Organic molecules of many kinds can form in the absence of life. This was a hot topic a couple centuries back. Astronomers have found evidence of all kinds of complex organic molecules in free space including amino acids and even the compound that gives raspberries their distinctive smell.

  • Eric Copenhaver

    It’s true that organic compounds can form in the absence of living organisms. It may have been a hot topic, ‘centuries back’ (mind a citation or something? Name-drop some dead old astronomer- he won’t mind! it’s just your word, otherwise…), but I would argue that it is now a hot topic, and will remain so, until we understand how specific deposits of organics come to reside at specific locations.
    Example: How did these specific organics get to be located on a Main Belt asteroid, when there are no apparent processes in the local environment of the Main Belt, that could synthesize the organics in question?
    Now, I know they find ‘a few’ kinds of organics in free space, but again, I’m not so sure about ‘all kinds’ of organic molecules being observed, or inferred. Again, would you care to drop a citation, here?