Seven key facts about Cassini's Oct. 28 'plume dive'

October 26, 2015
This daring flyby will bring the Cassini spacecraft within 30 miles (48 kilometers) of Enceladus' south pole. Credit: NASA/JPL-Caltech

NASA's Cassini spacecraft will sample the ocean of Saturn's moon Enceladus on Wednesday, Oct. 28, when it flies through the moon's plume of icy spray.

Cassini launched in 1997 and entered orbit around Saturn in 2004. Since then, it has been studying the huge planet, its rings and its magnetic field. Here are some things to know about the mission's upcoming close of Enceladus:

— Enceladus is an icy moon of Saturn. Early in its mission, Cassini discovered Enceladus has remarkable geologic activity, including a towering plume of ice, water vapor and organic molecules spraying from its . Cassini later determined the moon has a global ocean and likely hydrothermal activity, meaning it could have the ingredients needed to support simple life.

— The flyby will be Cassini's deepest-ever dive through the Enceladus plume, which is thought to come from the ocean below. The spacecraft has flown closer to the surface of Enceladus before, but never this low directly through the active plume.

— The flyby is not intended to detect life, but it will provide powerful new insights about how habitable the ocean environment is within Enceladus.

— Cassini scientists are hopeful the flyby will provide insights about how much hydrothermal activity—that is, chemistry involving rock and hot water—is occurring within Enceladus. This activity could have important implications for the potential habitability of the ocean for simple forms of life. The critical measurement for these questions is the detection of molecular hydrogen by the spacecraft.

— Scientists also expect to better understand the chemistry of the plume as a result of the flyby. The low altitude of the encounter is, in part, intended to afford Cassini greater sensitivity to heavier, more massive molecules, including organics, than the spacecraft has observed during previous, higher-altitude passes through the plume.

— The flyby will help solve the mystery of whether the is composed of column-like, individual jets, or sinuous, icy curtain eruptions—or a combination of both. The answer would make clearer how material is getting to the surface from the below.

— Researchers are not sure how much icy material the plumes are actually spraying into space. The amount of activity has major implications for how long Enceladus might have been active.

An online toolkit for all three final Enceladus flybys is available at: solarsystem.nasa.gov/finalflybys

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9 comments

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cantdrive85
1.8 / 5 (5) Oct 26, 2015
Here's another fact, they're sending the craft through a highly charged environment. "Safe Mode" could be the result.
matt_s
5 / 5 (7) Oct 27, 2015
Can you calculate for us, according to your theory, what kind of charge (even order of magnitude) will be experienced? So we can know for future planning? Or is your theory all hand-waving?
Vietvet
4.1 / 5 (9) Oct 27, 2015
Canti is a member of the Thunderbolt cult, they don't have theories, All their claims are "facts" in their delusional way of believing.
yep
1.7 / 5 (6) Oct 27, 2015
The earth has a vertical electrical field, there can be a two hundred volt difference from your head to your toes, go up 100 feet and there can be 3000 volt difference. Why the idea of charge differentials in space is anathema to some of you is perplexing.
Doug_Huffman
5 / 5 (1) Oct 27, 2015
Maybe y'all above should study with Michio Kaka of whom Cassini/Huygens' grand successes should be the ultimate impeachment.
Torbjorn_Larsson_OM
4 / 5 (8) Oct 27, 2015
Exciting!

@cantcount: Saturn's neighborhood is rather lenient, so little bulk charging compared to Jupiter.

What do you mean by "charged"? Space plasma is neutral: "For typical surfaces at geosynchronous altitudes, it takes a few milliseconds to come to a charging equilibrium. ... Electrons of 0.1 eV can charge surfaces to 0.1 V at most." [ http://press.prin...9500.pdf ]

@yep: Earth's surface is near neutral, carries ~ 1 nC/m^2 charge. [ https://en.wikive...he_Earth ] If your dry skin resistance is up to 100 kOhm [ https://van.physi...?id=6793 ], you discharge any pickup of _very_ large feet over a time ~ RC ~ 10^5*10^-9 ~ 10 ms.

You will never have 200 V between your head and toes, naturally. Nor does it has anything to do with spacecraft charging which is mediated by particle, not fields (see ref above). Your argument seems to be an argument from tales for children.
bschott
1.7 / 5 (6) Oct 27, 2015
What do you mean by "charged"? Space plasma is neutral:


Neutral plasma...really. So there is no difference in behavior between a neutral gas exposed to a magnetic field vs. a plasma exposed to a magnetic field?

Another home run T-bone.
JustAnotherGuy
3.7 / 5 (3) Oct 27, 2015
Here's another fact, they're sending the craft through a highly charged environment. "Safe Mode" could be the result.

It sounds "highly speculative". Is like this:
-Hmm.... a new crater or canyon, over the spacecraft's "surface" (:p), could be the result...

Hey, that was easy... no wonder they always attempt...
jonesdave
4 / 5 (4) Oct 28, 2015
Here's another fact, they're sending the craft through a highly charged environment. "Safe Mode" could be the result.


But apparently wasn't.

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