Dwarf planet Ceres has 'key ingredients for life'

Ernutet crater is featured in this image from Ceres taken by NASA’s Dawn spacecraft.     NASA  JPL-Caltech  UCLA  MPS  DLR  IDA

Together with some of the other stuff already known to be on Ceres, this makes for what could theoretically be a life-friendly environment, perhaps even an environment with the right chemical precursors for life.

It is the largest object in the asteroid belt, yet the dwarf planet, Ceres, has been surprising scientists ever since it was discovered. Marchi is one of the authors of a paper on the findings that will be published Friday in the journal Science.

"We prefer the hypothesis of formation in Ceres itself", says first author Maria Cristina De Sanctis.

"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'.

Evidence of Ceres' organic material comes from areas near Ernutet crater. The compounds, they say, wouldn't have survived the extreme heat of such an impact, and their distribution on Ceres's surface doesn't match up with the type that a cosmic accident might produce. Nor does their pattern of distribution across Ceres's surface fit with an impact theory.

The researchers also think that the compounds were generated on Ceres, instead of being brought there by an asteroid or comet. In this scenario, hydrothermal energy would likely power volcanoes that push liquid water from deep below onto the surface of Ceres.

De Sanctis agrees, noting that while it's possible to get a mix of impacted material and target material, that's not the main hypothesis in this case. When sunlight hits Ceres, some of the surface materials absorb the light while others reflect it. Organic molecules are interesting to scientists because they are necessary, though not sufficient, components of life on Earth.

It lies less than three times as far as Earth from the sun - close enough to feel the warmth of the star, allowing ice to melt and reform.

When we're differentiating between organic molecules that might indicate life and the ones that are just molecules, the factor most important to bear in mind is temperature, explains NASA planetary protection officer Catharine Conley. Indeed, "Ceres shows clear signatures of pervasive hydrothermal activity and aqueous adjustment", they wrote in the new study.

It's important to contextualize the discovery not just in relation to Mars and various distant moons, but in relation to everything out there we haven't had the chance to study yet.

For life to begin, you need elements like carbon, hydrogen, nitrogen and oxygen, as well as a source of energy. "So there is still plenty of work to be done before we can start thinking about whether microbes were able to form on Ceres". Studying Ceres could provide humans with a better understanding of the origins of life on Earth-and why we haven't found it elsewhere in the solar system.

There is high interest in the mission because Ceres is seen as being a record of the early solar system. Organic compounds, including amino acids, occur in some chondritic meteorites, possibly formed during aqueous adjustment on their parent bodies (2,3,4) and/or as the result of interstellar photochemistry (5). It was the signature of a class of organic molecules that have methyl and methylene groups. The discovery was made by the Dawn mission, which has previously found evidence of water ice at the planet's poles and carbonate minerals, that appear to be responsible for the mysterious bright spots on the surface.



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