Our Closest View Yet of Ceres’ Bright Spots

By Carl Engelking | March 22, 2016 5:14 pm
ceres-spots

Dawn’s close-up view of Ceres — 240 miles from its surface — reveals a dome in a smooth-walled pit in the bright center of the crater. (Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI)

Since April 2015, NASA’s Dawn spacecraft has been drawing ever closer to Ceres, and it’s now provided the closest view yet of the dwarf planet.

Scientists on Tuesday unveiled images captured by Dawn from it lowest orbit at Ceres—some 240 miles above its surface—during the Lunar and Planetary Science Conference in Texas. The latest set of images brings Ceres’ puzzling bright spots into sharper focus.

wide-view

A wider view of the Occator Crater. (Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI)

The brightest area on Ceres is in the middle of the 57-mile-wide, 2-mile-deep Occator Crater. From afar, it looked as if the crater contained two, distinct spots. But as Dawn has orbited closer, its captured images that have revealed bright areas that are far more intricate than previously thought.

The latest close-ups show that one of the “spots” is a dome at the center of the pit, with fractures and other linear features crisscrossing over its top and sides. The deformities suggest the area was geologically active in the recent past.

enhanced-spots

An enhanced color image from NASA’s Dawn spacecraft highlights subtle color differences on Ceres’ surface. (Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI/LPI)

“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,” Ralf Jaumann, planetary scientist and Dawn co-investigator at the German Aerospace Center in Berlin, said Tuesday.

In a study published in the journal Nature back in December, researchers crunched data from Dawn and concluded that Ceres’ spots are likely caused by hydrated magnesium sulfate — similar to Epsom salt — that’s present at the bottom of craters.

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  • http://www.mazepath.com/uncleal/qz4.htm Uncle Al

    Epson salts (magnesium sulfate heptahydrate, [CAS 10034-99-8]) has vapor pressure 8 torr/20 °C. How does it stay hydrated in hard vacuum when facing the sun, including solar vacuum UV? Water photodissociation resonant peaks are at 8.3 (149 nm) and 9.6 eV (129 nm), then continuum absorption coefficient greater than 8×10^5 cm^(-1). Sulfate also photodissociates.

    J. Chem. Phys. 51, 243 (1969), doi:10.1063/1.1671714

    • Kurt S

      I am just a layman, but I think I might have some answers (although I barely understood your questions). I think evaporation of the salts would depend upon its time being deposited, and its thickness, and not discounting its depth in the crater (shadowing effect from direct sunlight). In other words, how much thickness of salts would evaporate during sunlight exposure at that distance from sun. Lets say it gets (for the sake of arguement, I have no bases for any formula) 3 hours of direct sunlight every 7 years and the deposit is 200 feet deep. How long would it take to make that deposit disappear?

  • Mike Richardson

    Funny, I was thinking “salt dome” when I saw the close-up. There’s a locally well-known one here in Louisiana, at Avery Island (where the Tabasco Sauce is made). So it looks like Ceres likely has some frozen water, salts, and other minerals, all of which could make it pretty valuable for future human exploration and settlement in the asteroid belt.

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