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Ceres covered in hidden ice, studies suggest

Ceres craters in permanent shadow marked marked in blue.

At the poles of Ceres, scientists have found craters that are permanently in shadow (indicated by blue markings). Such craters are called “cold traps” if they remain below about minus 240 degrees Fahrenheit (minus 151 degrees Celsius). Image & Caption Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

The Jet Propulsion Laboratory (JPL) and NASA have announced a series of new findings from the Dawn spacecraft currently orbiting the dwarf planet Ceres that point to the existence of ice within its crust.

Using the spacecraft’s gamma-ray and neutron detector (GRaND), researchers were able to determine the concentrations of hydrogen, iron, and potassium in the uppermost meter of Ceres’ crust. On Ceres, hydrogen is most likely to occur in the form of frozen water.

Permanently shadowed crater on Ceres

A permanently shadowed crater on Ceres. Image Credit: NASA / JPL-Caltech / UCLA / MPS / DLR / IDA

The GRaND instrument measures the number and energy of gamma rays and neutrons being absorbed and escaping from Ceres. Hydrogen is known to slow down neutrons and is associated with fewer neutrons escaping.

GRaND data has also been able to determine the ice is likely filling the pore space of a rocky material mixture that is thought to be about 10 percent ice by weight.

“On Ceres, ice is not just localized to a few craters. It’s everywhere, and nearer to the surface with higher latitudes,” said Thomas Prettyman, principal investigator of GRaND, which is based at the Planetary Science Institute in Tucson, Arizona. “These results confirm predictions made nearly three decades ago that ice can survive for billions of years beneath the surface of Ceres. The evidence strengthens the case for the presence of near-surface water ice on other main belt asteroids.”

A second study examined hundreds of craters called “cold traps”, which are permanently shadowed with temperatures below minus 260 degrees Fahrenheit (minus 162 degrees Fahrenheit) that are so cold very little water ice is converted to vapor. Researchers found deposits of bright material in 10 craters, with the presence of ice being confirmed in one of them by using Dawn’s infrared mapping spectrometer.

The study, led by Thomas Platz of the Max Planck Institute for Solar System Research in Gottingen, Germany, and published in the journal Nature Astronomy, suggests water ice can be stored in the cold traps craters on Ceres. Ice in cold traps has been observed previously on Mercury and on Earth’s Moon. However, the origins of water ice on Ceres remains a mystery.

“We are interested in how this ice got there and how it managed to last so long,” said study co-author Norbert Schorghofer of the University of Hawaii. “It could have come from Ceres’ ice-rich crust or it could have been delivered from space.”

JPL also announced in the same press release a series of bright spots inside Occator Crater have now been named. The bright spots were first observed as Dawn was approaching Ceres and are now thought to be salt deposits, although their precise origins are still under investigation. The bright spot at the center of the crater has been named Cerealia Facula and a cluster of less reflective spots to the east have been named Vinalia Faculae.

The Dawn spacecraft launched in 2007 and has been orbiting Ceres since 2015 after spending over a year orbiting the asteroid Vesta. Its mission is scheduled to conclude in 2017 after which it will be left to orbit Ceres as a perpetual satellite.

Video courtesy of NASA’s Jet Propulsion Laboratory

 

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Paul is currently a graduate student in Space and Planetary Sciences at the University of Akransas in Fayetteville. He grew up in the Kansas City area and developed an interest in space at a young age at the start of the twin Mars Exploration Rover missions in 2003. He began his studies in aerospace engineering before switching over to geology at Wichita State University where he earned a Bachelor of Science in 2013. After working as an environmental geologist for a civil engineering firm, he began his graduate studies in 2016 and is actively working towards a PhD that will focus on the surficial processes of Mars. He also participated in a 2-week simluation at The Mars Society's Mars Desert Research Station in 2014 and remains involved in analogue mission studies today. Paul has been interested in science outreach and communication over the years which in the past included maintaining a personal blog on space exploration from high school through his undergraduate career and in recent years he has given talks at schools and other organizations over the topics of geology and space. He is excited to bring his experience as a geologist and scientist to the Spaceflight Insider team writing primarily on space science topics.

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