Rosetta detects magnetic-free bubble around comet

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Scientists using Rosetta have finally detected the expected bubble or region surrounding Comet 67P/C-G where there is no magnetic field and the Sun’s solar wind does not enter.

The bubble is caused by the material being ejected from the comet. Scientists had detected the same thing around Halley’s Comet back in 1986, but it turns out the bubble around Comet 67P/C-G is larger than expected based on those previous measurements, and also fluctuates in size more than predicted.


  • Steve Earle

    Very interesting, I wonder if this may lead to something we could use for shielding spacecraft.

  • Dick Eagleson

    Staying on the shady side of a comet may be a good way to shield future large traveling space habs that cycle between the inner and outer solar system from solar-origin radiation, though it would be of only limited help against extra-solar high energy cosmic rays. Might require significant station-keeping propellant, over time, to overcome both the miniscule pull of a cometary “primary” and keep the habs from orbiting said primaries though. I doubt most comets have the right mass to allow for a sun-synchronous orbit within the “bubble” locus described in the article. More or less continuous active thrusting would be required. Perhaps mining and refining mass obtained from said primaries would provide a ready source of usable reaction mass? For actual transport ships, though, dragging around an entire comet as shielding seems less efficient than dragging around just the minimum anti-radiation “armor” required not to frizzle in the natural radiation environment of deep space over a long career.

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