Ceres Bright Spots Mesmerize In Striking New Close-Up Photo

This image, made using images taken by NASA's Dawn spacecraft, shows Occator crater on Ceres, home to a collection of intriguing bright spots. Because these spots are so much brighter than the rest of Ceres' surface, the Dawn team combined two different images into a single composite view — one properly exposed for the bright spots, and one for the surrounding surface. Credits: Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
Occator crater on Ceres is home to a collection of intriguing bright spots. Because these spots are so much brighter than the rest of Ceres’ surface, the Dawn team combined two different images into a single composite view  one properly exposed for the bright spots, and one for the surrounding surface. Click to enlarge. Credits: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

New images taken from Dawn’s current orbit of just 915 miles (1,470 kilometers) above the dwarf planet Ceres show the ever-mysterious white spots in much greater detail than ever before. The image above has about three times better resolution than the images the spacecraft delivered from its previous orbit in June, and nearly 10 times better than in the spacecraft’s first orbit at Ceres in last spring.


Circle Occator Crater from above to get a feel for its topography

Finally, we can see sensible details including complex textures in the white spots spattered about the 60-mile-wide (90 km) Occator Crater. The crater itself is remarkable with a depth of 4 miles (6.4 km) and walls that are in places nearly vertical. The floor looks filled with what appears to be impact melted rock from the terrific blow that created the crater. Narrow cracks surround the central, white-topped peak.

Dawn Mission principal investigator Chris Russell. Credit: Reed Hutchinson, UCLA
Dawn Mission principal investigator Chris Russell. Credit: Reed Hutchinson, UCLA

Just what the highly reflective material is that makes the spots so white is under analysis right now after Dawn mission scientists took readings of the spots using the spacecraft’s visual and infrared mapping spectrometer or VIR. However, a recent interview with the Dawn mission’s Principal Investigator Christopher Russell by Linda Moulton Howe of Earthfiles.com, sheds a shaft of light on the mystery. Russell believes the white material is a thick dusting of some sort of powder and that whatever lies beneath the surface has been puffing out the material for some time, since the same bright spotted region appears in Hubble images taken back in 2004.

If the spots were made of ice, they would have vaporized in the near-zero atmospheric pressure on Ceres. Russell compared it to a dry lake bed salt deposit seen in many deserts across the world. Since he’s heard no report of ice detection from the team working on the VIR data, he’s assuming it’s salt. Keep in mind, this is his best guess based on limited data.

Earlier and current view of Occator Crater and the white spots scaled to the same size. The lower resolution and different method of processing the two images made the spots
Earlier (left) and current views of Occator Crater and the white spots. Lower resolution and a different method of processing the two images caused the spots to appear far more dramatic in older photos.  Credits: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Could a meteorite strike have punched through Ceres’ crust into an icy layer beneath? Heated by impact, the ice would briefly liquify and possibly spray to the surface before freezing and then vaporizing into space. Left behind would be a mineral residue, likely salt, which easily dissolves in water. Salts are good reflectors of light and would stand out as bright patches against the dwarf planet’s darker surface.

We should know soon.

3 Responses

  1. Troy

    I’m starting to think it is probably residual salts. Assuming Ceres has an icy mantle, which is unlikely to be pure water, after an impact that ruptures the mantle frozen brine forms a central peak. The water sublimates to space leaving behind salts which are typically white. The spots remind me of spilled baking powder, they just don’t look like ice to me anymore. (My previous opinion was ephemeral ice formations)

  2. I.dare.dog.Moss

    Recall the Phoenix lander on Mars excavated water ice which soon sublimated away. The Ceres “white stuff” has had a longer life span than that, so some sort of salt fits the evidence.

    1. astrobob

      L.Dare,
      Good point on Phoenix – thanks! I agree. Sublimating ice leaving behind salt seems a good choice based on the evidence so far.

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