Dwarf Planet Ceres Likely Made Own Organic Molecules, Scientists Say
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After a close-up examination of the nearby dwarf planet Ceres, which orbits inside the Asteroid Belt---revealed the presence of organic compounds---scientists went looking for an explanation. Now, they think they can dismiss the idea that the molecules were deposited by asteroid impacts.
When NASA’s Dawn spacecraft orbited Ceres between 2015 and 2018, it detected water in several forms on the planet, including vapor and brine in the crust, and spotted organic compounds called aliphatic molecules on the surface near a massive impact crater.
Research presented at the Geological Society of America’s GSA Connects 2023 meeting earlier this week demonstrated how scientists have attempted to explain the presence of these molecules, which are similar to hydrocarbons like those found in fossil fuels here on Earth.
Their research suggests the molecules were most likely developed on the planet itself, rather than deposited by asteroids carrying the materials.
14 September 2023, 21:02 GMT
Their research looked at whether organic molecules like those on the planet could exist after an asteroid strike, so they used a hypervelocity gun to reproduce in their lab the conditions of an asteroid strike on Ceres. They tested speeds of between 4,400-13,000 miles per hour and strike angles of between 15 and 90 degrees to the horizontal.
“The organics were initially detected in the vicinity of a large impact crater, which is what motivated us to look at how impacts affect these organics,” Terik Daly, a planetary scientist at Johns Hopkins Applied Physics Laboratory who led the study, said in a statement. “We are finding that organics may be more widespread than first reported and that they seem to be resilient to impacts with Ceres-like conditions.”
The scientists also combined data from two different sources on the Dawn spacecraft - its camera data and its spectrometer - and made a startling discovery.
“People had looked at the Dawn camera data and the Dawn spectrometer data separately, but no one else had taken the approach our team used to extrapolate the data from one instrument to another, which provided new leverage in our search to map and understand the origin of organics on Ceres,” said co-author Jessica Sunshine of the University of Maryland.
“By capitalizing on the strengths of two different datasets collected over Ceres, we’ve been able to map potential organic-rich areas on Ceres at higher resolution. We can see a very good correlation of organics with units from older impacts and with other minerals like carbonates that also indicate the presence of water. While the origin of the organics remains poorly understood, we now have good evidence that they formed in Ceres and likely in the presence of water,” noted Juan Rizos, an astrophysicist at Spain’s Instituto de Astrofisica de Andalucia.
“There is a possibility that a large interior reservoir of organics may be found inside Ceres. So, from my perspective, that result increases the astrobiological potential of Ceres.”
