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posted by Fnord666 on Monday October 30 2017, @07:31AM   Printer-friendly
from the surfing-a-moon dept.

Dawn Finds Possible Ancient Ocean Remnants at Ceres

Minerals containing water are widespread on Ceres, suggesting the dwarf planet may have had a global ocean in the past. What became of that ocean? Could Ceres still have liquid today? Two new studies from NASA's Dawn mission shed light on these questions.

The Dawn team found that Ceres' crust is a mixture of ice, salts and hydrated materials that were subjected to past and possibly recent geologic activity, and that this crust represents most of that ancient ocean. The second study builds off the first and suggests there is a softer, easily deformable layer beneath Ceres' rigid surface crust, which could be the signature of residual liquid left over from the ocean, too.

"More and more, we are learning that Ceres is a complex, dynamic world that may have hosted a lot of liquid water in the past, and may still have some underground," said Julie Castillo-Rogez, Dawn project scientist and co-author of the studies, based at NASA's Jet Propulsion Laboratory, Pasadena, California.

Ceres.

Constraints on Ceres' internal structure and evolution from its shape and gravity measured by the Dawn spacecraft (open, DOI: 10.1002/2017JE005302) (DX)

The interior structure of Ceres as revealed by surface topography (DOI: 10.1016/j.epsl.2017.07.053) (DX)

Previously: Dawn Spies Magnesium Sulphate and Possible Geological Activity on Ceres
Ceres's Cryovolcanoes Viscously Relax Into Nothingness
Organic Molecules Found on Ceres
Early Asteroids May Have Been Made of Mud Rather Than Rock
Dawn Mission Extended at Ceres


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  • (Score: 4, Informative) by takyon on Monday October 30 2017, @06:37PM (1 child)

    by takyon (881) <reversethis-{gro ... s} {ta} {noykat}> on Monday October 30 2017, @06:37PM (#589585) Journal

    https://www.google.com/search?q=site:soylentnews.org+Ceres [google.com]

    We have lots of articles on Ceres, including one 10 days ago. At some point jokes are the only thing that are going to be added unless the article proposes a mission there.

    Actually, solar power can be used at Ceres. It can be used as far as Jupiter: https://www.jpl.nasa.gov/news/news.php?feature=4818 [nasa.gov]

    The four-ton Juno spacecraft carries three 30-foot-long (9-meter) solar arrays festooned with 18,698 individual solar cells. At Earth distance from the sun, the cells have the potential to generate approximately 14 kilowatts of electricity. But transport those same rectangles of silicon and gallium arsenide to a fifth rock from the sun distance, and it's a powerfully different story.

    "Jupiter is five times farther from the sun than Earth, and the sunlight that reaches that far out packs 25 times less punch," said Rick Nybakken, Juno's project manager from NASA's Jet Propulsion Laboratory in Pasadena, Calif. "While our massive solar arrays will be generating only 500 watts when we are at Jupiter, Juno is very efficiently designed, and it will be more than enough to get the job done."

    The Dawn mission to Ceres uses solar power: https://en.wikipedia.org/wiki/Dawn_(spacecraft)#Specifications [wikipedia.org]

    https://en.wikipedia.org/wiki/Sunlight#Intensity_in_the_Solar_System [wikipedia.org]

    45.9 W/m2 minimum for Jupiter, 715 W/m2 maximum for Mars. Ceres is somewhere in between.

    https://www.space.com/31584-dwarf-planet-ceres-colonization-the-expanse.html [space.com]

    the dwarf planet receives about 10 times less sunlight than Earth.

    "You just have to put out 10 times as many solar panels,"

    So about 2.5 more solar intensity than Juno is getting while orbiting Jupiter. Or is it?

    This page [pveducation.org], with inputs 382.62, 414.01, 445.41 (x109 meters) gives me:

    Perihelion = 382.62 x 109 m = 2.5577 AU
    197.69 W/m2

    Semi-major axis = 414.01 x 109 m = 2.7675 AU
    168.85 W/m2

    Aphelion = 445.41 x 109 m = 2.9773 AU
    145.88 W/m2

    So on average, Ceres gets a bit closer to 1/8 of the solar intensity near Earth-Moon rather than 1/10. Over three times what Jupiter gets, and Jupiter gets more like 1/27 than 1/25 what Earth gets.

    The dip when approaching aphelion could be trouble, but it is entirely possible to use a useful amount of solar power at Ceres.

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  • (Score: 2) by bob_super on Monday October 30 2017, @06:42PM

    by bob_super (1357) on Monday October 30 2017, @06:42PM (#589592)

    Even if you can calculate that, do not tell the odds of a spacecraft surviving a visit to a planet in an asteroid belt.