Herschel Crater on Mimas

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Herschel Crater on Mimas

Cool image time! The photo on the right was taken by Cassini on October 22, 2016 when the spacecraft was about 115,000 miles away and has a resolution of about 3,300 feet per pixel. It highlights well Mimas’ most distinctive feature, its single gigantic crater, which also makes the tiny moon of Saturn one of the more distinctive planetary bodies in the entire solar system.

Named after the icy moon’s discoverer, astronomer William Herschel, the crater stretches 86 miles (139 kilometers) wide — almost one-third of the diameter of Mimas (246 miles or 396 kilometers) itself.

Large impact craters often have peaks in their center — see Tethys’ large crater Odysseus in The Crown of Tethys. Herschel’s peak stands nearly as tall as Mount Everest on Earth.

The mystery here is how did Mimas survive such an impact. One would think that the moon would be been split apart by the collision, and that it didn’t suggests the material involved was soft enough to absorb the dynamic forces, and that the speed of the impact was slow enough to reduce those forces overall.


  • mkent

    That’s no moon!

    Of course there’s a peak in the center. That’s where the laser fires from.

  • PeterF

    The high albedo of Mimas leads to the theory that the moon is a giant snowball. The peak is probably the slow motion splash that froze before it had a chance to subside. Since water has been described as the most important substance for solar system exploration, this is probably one of the most valuable objects in the solar system (along with the methane available on Titan). There appear to be lots of iron/nickel bodies in the asteroid belt to build vessels.

  • LocalFluff

    Just a random distribution of craters, with that big one obviously from some time ago. No obvious evidence of volcanism or tidal heating or such as seen on some objects from our Luna out to Pluto. Just rocks hitting rock. Must be useful as an historical archive, kind of a reference.

  • Alex

    LocalFluff: Let us trow Mimas at Venus in order accelerate Venus’ roation, supply water ans eject some of its atmosphere. :-)

  • Localfluff

    @Alex, Heck, I think that is what happened to Venus in order to GIVE it its atmosphere! That an icy comet hit it, stopped its rotation, resurfaced it and brought lots of CO2. Maybe it goes the other way too depending on angle of impact.

  • Alex

    @LocalFluff: I think, CO2 was already already there. Venus and Earth own about some total CO2 mass, but in Earth’s case it is bounded at most in limestone (by acient and former life activity), what is not the case of Venus, where it is a free gas.

  • PeterF

    If we’re talking about terraforming Venus we would have to REMOVE atmosphere and cool the surface. what could we do with the hot gas? How about drop it on Mars, thickening the atmosphere and warming the surface? I envision a convoy of robotic atmospheric mining craft scooping the upper atmosphere of Venus and depositing it on Mars. They would probably have to be driven by a combination solar sails and ion engines. Tech available today!
    Several thousands of these craft operating continuously in a loop for several thousand years would eventually terraform both planets and give humans three worlds.

  • Alex

    @PeterF: I do not think that a human society is abte to work thousands of years on a single project. Think about, even required 10 years political support of space project is very seldom. Your scenario becomes possible if it c space launch cost nears about 0.00001 dollar/kg and the job can be done in 30 years or so. Space ship that can transport a million tons at once.

  • LocalFluff

    Switch places of Venus and Mars, and we would have three habitable planets in the Solar system.

  • Edward

    Alex wrote: “I do not think that a human society is abte to work thousands of years on a single project.

    Maybe not, but the Islamic worldwide-caliphate project has been going on for quite a few centuries.

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