Closest Dawn images reveal detailed craters, terrains
Orbiting just 240 miles (385 km) above the surface of Ceres, NASA’s Dawn spacecraft has captured detailed images of the dwarf planet’s craters and various terrains. Kupalo Crater (above), one of the youngest craters on Ceres, reveals many fascinating attributes at the high image resolution of 120 feet (35 meters) per pixel.
Taken between December 19 and 23, 2015, the images show craters with unusual features including steep slopes, bright mineral deposits, and networks of fractured terrain on their floors.
Kupalo Crater is 16 miles (26 km) wide, with a flat floor that was likely formed by a combination of debris and melt from an impacting object.
Like Occator Crater, whose famous bright spots have mystified scientists and the public for almost a year, Kupalo Crater also has a layer of bright material along its rim, which could be composed of salts.
Mission scientists are studying the crater in more detail to determine whether there is any connection between its bright material and the spots on Occator Crater.
“This crater and its recently formed deposits will be a prime target of study for the team as Dawn continues to explore Ceres in its final mapping phase,” noted science team member Paul Schenk of Houston’s Lunar and Planetary Institute.
The top-right image (click to enlarge) shows part of Messor Crater (25 miles, or 40 km, wide), located at northern mid-latitudes on Ceres.
The scene depicts an older crater in which a large lobe-shaped flow partially covers the northern (top) part of the crater floor, resulting from the flow of material ejected when a younger crater formed just north of the crater’s rim.
Shown in the middle-right image (click to enlarge), the 78-mile (126 km) wide Dantu Crater has a closely-packed network of fractures on its floor, a feature that it shares with Tycho, one of the youngest craters on Earth’s moon.
The fractures could have been produced when an impacting body melted and subsequently cooled, or they could have developed when the bottom of the crater was lifted up following the crater’s formation.
Just west of Dantu, shown in the bottom-right image (click to enlarge), sits a smaller, 20-mile (32 km) crater with numerous ridges and steep slopes known as scarps. Covered in curved lines, the scarps resemble similar features on the floor of the huge crater Rheasilvia on the protoplanet Vesta, also observed by Dawn.
Scientists surmise that the ridges and scarps on this smaller crater were created early during its formation when part of the crater collapsed.
The mission has slightly less than six months left. When it ends on June 30, 2016, the spacecraft will not be crashed onto the planet but be left in its current orbit.
Chris Russell, the principal investigator for the Dawn mission, based at the University of California, Los Angeles, said the mission team expected to be surprised by the findings at Ceres. When the spacecraft entered this close orbit last month, its other instruments also took advantage of the position to undertake a new round of intensive study.
“Ceres does not disappoint,” Chris Russell said. “Everywhere we look in these new, low-altitude observations, we see amazing landforms that speak to the unique character of this most amazing world.”
To identify minerals on Ceres’ surface, Dawn‘s infrared and visible mapping spectrometers are studying the way the dwarf planet reflects various wavelengths of light.
Another science instrument, the Gamma-ray and neutron detector (GRaND), is collecting data about the many elements on Ceres’ surface that will reveal more about its composition and will also provide key insight into the small world’s evolution and development.
Image Credits: NASA / JPL-Caltech / UCLA / MPS / DLR / IDA
Laurel Kornfeld
Laurel Kornfeld is an amateur astronomer and freelance writer from Highland Park, NJ, who enjoys writing about astronomy and planetary science. She studied journalism at Douglass College, Rutgers University, and earned a Graduate Certificate of Science from Swinburne University’s Astronomy Online program. Her writings have been published online in The Atlantic, Astronomy magazine’s guest blog section, the UK Space Conference, the 2009 IAU General Assembly newspaper, The Space Reporter, and newsletters of various astronomy clubs. She is a member of the Cranford, NJ-based Amateur Astronomers, Inc. Especially interested in the outer solar system, Laurel gave a brief presentation at the 2008 Great Planet Debate held at the Johns Hopkins University Applied Physics Lab in Laurel, MD.
Great writeup, but I find the experts explanations a bit puzzling. It is difficult to believe that this particular crater was formed by some impact. There are no rounded edges along the rim and the crater bottom appears flat. It looks more like a section of the mantle was forced inward much like a cork being pulled into a wine bottle. This might be possible if the core is comprised of liquid water sealed inside a hard mantle. If the core is subjected to cyclic temperature variations then this might result in variable forces on the mantle.
It looks like a hexagonal rock vortice, with interference ripples of rock in a flat base that has been created by liquefaction of the surrounding material, as the rock rotated. You can see two hexagonal ring records in this caldera. You can see many more in other calderas, both on this dwarf planet and other planets and moons.A hexagonal rock vortex is the same as the hexagonal vortex, you get at the center of hurricanes.
Interference ripples and interference folding in rocks are well known features. I was taught about and shown these features in geology in the 1970’s and mapped them myself in 1980, and of course this was not new stuff then.
Many of the tiny ‘impact ‘ craters, I would attribute to Vesicular textures, the same as you get in bubbling vesicular lava, basalt or andesite, scoria, pumice or for that matter in swiss cheese or when you bake a cake. Just aeration holes as the gas escapes.
Chris Landau (geologist) January 16, 2016
P.S. Not every hole in the rock is from a meteorite, bollide, or asteroid impact. There are other causes, even though present day literature since the ‘dinosaur killing impact’has made, igneous cratons,volcanoes, calderas and erosion redundant.