Landslides and Bright Craters on Ceres Revealed in Marvelous New Images from Dawn

Ceres' Haulani Crater, with a diameter of 21 miles (34 kilometers), shows evidence of landslides from its crater rim.  Credits: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
Ceres’ Haulani Crater, with a diameter of 21 miles (34 kilometers), shows evidence of landslides from its crater rim. Credits: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Now in orbit for just over a year at dwarf planet Ceres, NASA’s Dawn spacecraft continues to astound us with new discoveries gleaned from spectral and imagery data captured at ever decreasing orbits as well as since the probe arrived last December at the lowest altitude it will ever reach during the mission.

Mission scientists have just released marvelous new images of Haulani and Oxo craters revealing landslides and mysterious slumps at several of the mysterious bright craters on Ceres – the largest asteroid in the main Asteroid Belt between Mars and Jupiter.

The newly released image of oddly shaped Haulani crater above, shows the crater in enhanced color and reveals evidence of landslides emanating from its crater rim.

“Rays of bluish ejected material are prominent in this image. The color blue in such views has been associated with young features on Ceres,” according to the Dawn science team.

“Enhanced color allows scientists to gain insight into materials and how they relate to surface morphology.”

Look at the image closely and you’ll see its actually polygonal in nature – meaning it resembles a shape made of straight lines – unlike most craters in our solar system which are nearly circular.

”The straight edges of some Cerean craters, including Haulani, result from pre-existing stress patterns and faults beneath the surface,” says the science team.

Haulani Crater has a diameter of 21 miles (34 kilometers) and apparently was formed by an impacting object relatively recently in geologic time and is also one of the brightest areas on Ceres.

“Haulani perfectly displays the properties we would expect from a fresh impact into the surface of Ceres. The crater floor is largely free of impacts, and it contrasts sharply in color from older parts of the surface,” said Martin Hoffmann, co-investigator on the Dawn framing camera team, based at the Max Planck Institute for Solar System Research, Göttingen, Germany, in a statement.

The enhanced color image was created from data gathered at Dawn’s High Altitude Mapping Orbit (HAMO), while orbiting at an altitude of 915 miles (1,470 kilometers) from Ceres.

Data from Dawn’s VIR instrument shows that Haulani’s surface is comprised of different materials than its surroundings.

“False-color images of Haulani show that material excavated by an impact is different than the general surface composition of Ceres. The diversity of materials implies either that there is a mixed layer underneath, or that the impact itself changed the properties of the materials,” said Maria Cristina de Sanctis, the VIR instrument lead scientist, based at the National Institute of Astrophysics, Rome.

Since mid-December, Dawn has been orbiting Ceres in its Low Altitude Mapping Orbit (LAMO), at a distance of 240 miles (385 kilometers) from Ceres, resulting in the most stunning images ever of the dwarf planet.

By way of comparison the much higher resolution image of Haulani crater below, is a mosaic of views assembled from multiple images taken from LAMO at less than a third of the HAMO image distance – at only 240 miles (385 kilometers) above Ceres.

Haulani Crater at LAMO. NASA's Dawn spacecraft took this mosaic view of Haulani Crater at a distance of 240 miles (385 kilometers) from the surface of Ceres.  Credits: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI
Haulani Crater at LAMO. NASA’s Dawn spacecraft took this mosaic view of Haulani Crater at a distance of 240 miles (385 kilometers) from the surface of Ceres. Credits: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI

Dawn has also been busy imaging Oxo Crater, which despite its small size of merely 6-mile-wide (10-kilometer-wide) actually counts as a “hidden treasure” on Ceres – because it’s the second-brightest feature on Ceres!

Only the mysterious bright region comprising a multitude of spots inside Occator Crater shine more brightly on Ceres.

Most importantly, Oxo Crater is the only place on Ceres where Dawn has detected water at the surface so far. Via VIR, Dawn data indicate that the water exists either in the form of ice or hydrated minerals. Scientists speculate that the water was exposed either during a landslide or an impact.

“Little Oxo may be poised to make a big contribution to understanding the upper crust of Ceres,” said Chris Russell, principal investigator of the mission, based at the University of California, Los Angeles.

The signatures of minerals detected on the floor of Oxo crater appears to be different from the rest of Ceres.

Furthermore Oxo is “also unique because of the relatively large “slump” in its crater rim, where a mass of material has dropped below the surface.”

Oxo Crater on Ceres is unique because of the relatively large "slump" in its crater rim.  The 6-mile-wide (10-kilometer-wide) Oxo crater is the second-brightest feature on Ceres.  Credits: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI
Oxo Crater on Ceres is unique because of the relatively large “slump” in its crater rim. The 6-mile-wide (10-kilometer-wide) Oxo crater is the second-brightest feature on Ceres. Credits: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI

Dawn is Earth’s first probe in human history to explore any dwarf planet, the first to explore Ceres up close and the first to orbit two celestial bodies.

The asteroid Vesta was Dawn’s first orbital target where it conducted extensive observations of the bizarre world for over a year in 2011 and 2012.

The mission is expected to last until at least later into 2016, and possibly longer, depending upon fuel reserves.

Dawn will remain at its current altitude at LAMO for the rest of its mission, and indefinitely afterward, even when no further communications are possible.

Stay tuned here for Ken’s continuing Earth and planetary science and human spaceflight news.

Ken Kremer

Best NASA Images Yet Of Ceres’ Brightest Spot

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The bright central spots near the center of Occator Crater are shown in enhanced color in this view from NASA’s Dawn spacecraft. The view was produced by combining the highest resolution images taken in February 2016 at an image scale of 115 feet (35 meters) per pixel with color images obtained in September 2015 at a lower resolution added. Click for a highest-res view. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI

Ah, dome sweet dome. Scientists from NASA’s Dawn mission unveiled new images from the spacecraft’s lowest orbit at Ceres, including highly anticipated views of Occator Crater, at the 47th annual Lunar and Planetary Science Conference in The Woodlands, Texas, on Tuesday. The new images, taken from Dawn’s low-altitude mapping orbit (LAMO) of 240 miles (385 kilometers) above Ceres, reveal a dome in a smooth-walled pit in the bright center of the crater. Linear fractures crisscross the top and flanks of the dome with still more fractures slicing across the nearby plains.

Occator Crater, measuring 57 miles (92 kilometers) across and 2.5 miles (4 kilometers) deep, contains the brightest area on Ceres. Image Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI
Occator Crater, measuring 57 miles (92 kilometers) across and 2.5 miles (4 kilometers) deep, contains the brightest area on Ceres. This photo has been exposed to show detail in the crater and landscape, so the bright spots are overexposed. The closeup photos on the other hand are correctly exposed to show detail in the spots but necessarily underexpose the landscape and make it look very dark. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI

“Before Dawn began its intensive observations of Ceres last year, Occator Crater looked to be one large bright area. Now, with the latest close views, we can see complex features that provide new mysteries to investigate,” said Ralf Jaumann, planetary scientist and Dawn co-investigator at the German Aerospace Center (DLR) in Berlin. “The intricate geometry of the crater interior suggests geologic activity in the recent past, but we will need to complete detailed geologic mapping of the crater in order to test hypotheses for its formation.”

The bright central spots near the center of Occator Crater are shown in enhanced color in this view from NASA's Dawn spacecraft. The view was produced by combining the highest resolution images taken in February 2016 (at image scales 115 feet (35 meters) per pixel of 35 meters with color images obtained in September 2015 at a lower resolution. Click for a highest-res view. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI
Black and white view of the bright spots in Occator Crater. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI

Like me, you’ve probably been anticipating LAMO for months, when we’d finally get our clearest view of the famous “bright spots”. Spectral observations have shown that the patches are consistent with a magnesium sulfate called hexahydrite that resembles the more familiar Epsom salts here on Earth. Scientists think these salt-rich areas were residue left behind when water-ice sublimated in the past. Impacts from asteroids could have broken into Ceres’ crust and possibly unearthed salt-rich ices. Exposed to the vacuum of space, the ice would have sublimated (vaporized), leaving the salt behind.

This global map shows the surface of Ceres in enhanced color, encompassing infrared wavelengths beyond human visual range. Images taken using infrared (965 nanometers), green (555 nanometers) and blue (438 nanometers) spectral filters were combined to create this view. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI
This global map shows the surface of Ceres in enhanced color, including infrared wavelengths beyond human visual range. Photos were taken using infrared, green and blue filters and combined to create this view. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI

The team also released an enhanced color map of the surface of Ceres that reveals a diversity of surface materials and how they relate to Ceres’ landforms. The dwarf planet doesn’t have as many large impact basins as scientists expected, but the number of smaller craters generally matches their predictions. The blue material highlighted in the color map is related to flows, smooth plains and mountains, which appear to be very young surface features.

“Although impact processes dominate the surface geology on Ceres, we have identified specific color variations on the surface indicating material alterations that are due to a complex interaction of the impact process and the subsurface composition,” Jaumann said. “Additionally, this gives evidence for a subsurface layer enriched in ice and volatiles.”

 This map shows a portion of the northern hemisphere of Ceres with neutron counting data acquired by the gamma ray and neutron detector (GRaND) instrument aboard NASA's Dawn spacecraft. These data reflect the concentration of hydrogen in the upper yard (or meter) of regolith, the loose surface material on Ceres. The color information is based on the number of neutrons detected per second by GRaND. Counts decrease with increasing hydrogen concentration. The color scale of the map is from blue (lowest neutron count) to red (highest neutron count). Lower neutron counts near the pole suggest the presence of water ice within about a yard (meter) of the surface at high latitudes.

This map shows part of Ceres’ northern hemisphere with neutron counting data from Dawn’s gamma ray and neutron detector (GRaND) instrument and reflect the concentration of hydrogen in the upper yard (or meter) of regolith, the loose surface material on Ceres. Colors are based on the number of neutrons detected per second by GRaND. Counts decrease with increasing hydrogen concentration. The color scale of the map is from blue (lowest neutron count) to red (highest neutron count). Lower neutron counts near the pole suggest the presence of water ice within about a yard (meter) of the surface at high latitudes. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI

We’re learning more about that subsurface ice thanks to Dawn’s Gamma Ray and Neutron Detector (GRaND). Neutrons and gamma rays produced by cosmic rays interacting with the topmost yard (meter) of the loose rock and dust called regolith provide a fingerprint of Ceres’ chemical makeup. Lower counts indicate the presence of hydrogen, and since water’s rich in hydrogen (H2o), the results from GRanD suggest concentrations of water ice in the near-surface at high latitudes.

“Our analyses will test a longstanding prediction that water ice can survive just beneath Ceres’ cold, high-latitude surface for billions of years,” said Tom Prettyman, the lead for GRaND and Dawn co-investigator at the Planetary Science Institute, Tucson, Arizona.

Ceres’ Oxo Crater (right) is the only place on the dwarf planet where water has been detected on the surface so far. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI
Ceres’ Oxo Crater (right) is the only place on the dwarf planet where water has been detected on the surface so far. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI

Dawn scientists also reported that the Visual and Infrared Mapping Spectrometer (VIR) has detected water at Oxo Crater, a young, 6-mile-wide (9-kilometer-wide) feature in Ceres’ northern hemisphere. This water could either be bound up in minerals or exist as ice and may have been exposed during a landslide or impact or a combination of the two events.  Oxo is the only place on Ceres where water has been detected at the surface so far.

Ceres' Haulani Crater (21 miles, 34 kilometers wide) is shown in these views from the visible and infrared mapping spectrometer (VIR) aboard NASA's Dawn spacecraft. These views reveal variations in the region's brightness, mineralogy and temperature at infrared wavelengths. The image at far left shows brightness variations in Haulani. Light with a wavelength of 1200 nanometers is shown in blue, 1900 nanometers in green and 2300 nanometers in red. The view at center is a false color image, highlighting differences in the types of rock and ejected material around the crater. Scientists see this as evidence that the material in this area is not uniform, and that the crater's interior has a different composition than its surroundings.
Ceres’ Haulani Crater (21 miles, 34 kilometers wide) is shown in these views made with VIR. They reveal variations in the region’s brightness, mineralogy and temperature at infrared wavelengths in the types of rock and ejected material around the crater. Scientists see this as evidence that the material in this area is not uniform, and that the crater’s interior has a different composition than its surroundings. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI

Not only have scientists found evidence of possible extensive subsurface ice, but the composition of the surface is variable. Using VIR, which measures mineral composition by how those minerals reflect sunlight, they found that Haulani Crater shows a different proportion of surface materials than its surroundings. While the surface of Ceres is mostly made of a mixture of materials containing carbonates and phyllosilicates (clays), their relative proportion varies across the surface.

“False-color images of Haulani show that material excavated by an impact is different than the general surface composition of Ceres. The diversity of materials implies either that there is a mixed layer underneath, or that the impact itself changed the properties of the materials,” said Maria Cristina de Sanctis, the VIR instrument lead scientist.

All these cool stuff we’re finding out about this small body makes it nearly as exciting as Pluto. Taking a closer look is the best form of education.