Hubble observations of Ganymede, Teleconference on March 12, 2015 |
Hubble observations of Ganymede, Teleconference on March 12, 2015 |
Mar 10 2015, 06:13 AM
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#1
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Senior Member Group: Members Posts: 2530 Joined: 20-April 05 Member No.: 321 |
http://www.nasa.gov/press/2015/march/nasa-...n/#.VP6JwEJBDjI
This seems to hint at something momentous. Ganymede hasn't been breaking news very often since the Galileo mission ended, so what's the announcement? I would think that HST observations of Ganymede could only be worthy of a teleconference if it's one of these: 1) The existence of plumes/geysers as were observed at Europa. 2) Something interesting detected in Ganymede's very-thin atmosphere. 3) Something interesting deposited in the ices on the surface. One of the speakers, Joachim Saur, has had publications regarding Ganymede's surface, aurorae at Io, Enceladus, and was on the paper announcing plumes at Europa. Maybe we've got another Galilean with a buried ocean that sprays its contents skyward? |
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Mar 10 2015, 07:31 AM
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#2
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Senior Member Group: Members Posts: 1419 Joined: 26-July 08 Member No.: 4270 |
-------------------- -- Hungry4info (Sirius_Alpha)
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Mar 11 2015, 05:18 PM
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Newbie Group: Members Posts: 1 Joined: 9-August 13 From: Vallis Rhône, France, Eu, Sol3.0, Orionbridge N0° t= +4.354*10**17s Member No.: 6982 |
what's the announcement? The Nasa page says QUOTE These results will help scientists in the search for habitable worlds beyond Earth. Maybe one of your answers is right and this led to an upwards re-evaluation of the input energy needed to explain the thermal output from Ganymede. If tidal effects from forced libration were insufficient, then researchers may have needed to opt for a radioactive source from a long-lived radioactive isotope. Generalising, they would then find that very long-term radioactivity solves a similar problem for Ceres. The timing of the Ganymede conference would thus be very astute by bringing energy balance into the limelight. NASA might even get lucky by discovering another thermal imbalance around Pluto this summer. Whatever, their argument would be to suggest that other cold worlds far from their star (and even orphan planets) would also benefit from a similar heating mechanism. And so to a paradigm change for habitability without a habitability zone. Well, its just an idea. We'll see tomorrow ! -------------------- Yet portion of that unknown plain Will Hodge for ever be / And strange-eyed constellations reign / His stars eternally.
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Mar 12 2015, 05:03 PM
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#4
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Member Group: Members Posts: 125 Joined: 18-July 05 Member No.: 438 |
More info here: (and a google hangout in a couple of hours' time)
http://hubblesite.org/newscenter/archive/releases/2015/09 |
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Mar 12 2015, 05:03 PM
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#5
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Senior Member Group: Members Posts: 1419 Joined: 26-July 08 Member No.: 4270 |
NASA's Hubble Observations Suggest Underground Ocean on Jupiter's Largest Moon
http://www.nasa.gov/press/2015/march/nasa-...n/#.VQHGavnF8rU -------------------- -- Hungry4info (Sirius_Alpha)
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Mar 12 2015, 06:02 PM
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#6
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Junior Member Group: Members Posts: 40 Joined: 28-July 07 Member No.: 2984 |
I dream of the day when I can buy bottled water from various different planets and moons.
Be nice if a meteorite was on an intercept path with one of these bodies and we could witness the plume following impact. |
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Mar 12 2015, 06:47 PM
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#7
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Senior Member Group: Members Posts: 1729 Joined: 3-August 06 From: 43° 35' 53" N 1° 26' 35" E Member No.: 1004 |
is the paper available somewhere on the net? I thought it would be in today's Science but it's not there...
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Mar 12 2015, 07:55 PM
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#8
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Junior Member Group: Members Posts: 78 Joined: 20-September 14 Member No.: 7261 |
Saur's research group tends to publish in the (AGU) Journal of Geophysical Research / Space Science section, which is where you can also find it online.
http://onlinelibrary.wiley.com/wol1/doi/10...14JA020778/full |
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Mar 13 2015, 09:45 AM
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#9
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Member Group: Members Posts: 495 Joined: 12-February 12 Member No.: 6336 |
The presence of the magnetic field in itself had been seen as one indication of a subsurface layer of salty water. And that's what it is required for it to be electrically conductive to create the field in the first place.
So the detection of aurora is more an indication of how the magnetic field interacts with the environment there. What bugs me is that illustrations show the aurora as blue. No nitrogen have been detected in the very thin atmosphere of Ganymede. |
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Mar 13 2015, 10:32 AM
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#10
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Junior Member Group: Members Posts: 78 Joined: 20-September 14 Member No.: 7261 |
At the teleconference Saur corrected this by saying the aurora as seen from the surface would be red.
Should probably be more like orange-red/light red, possibly shifted towards yellow or green too. |
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Mar 13 2015, 11:37 AM
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#11
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Member Group: Members Posts: 813 Joined: 29-December 05 From: NE Oh, USA Member No.: 627 |
Draft of article from the Hubble site http://hubblesite.org/newscenter/archive/r...015/09/related/
The Search for a Subsurface Ocean in Ganymede with Hubble Space Telescope Observations of its Auroral Ovals http://hubblesite.org/pubinfo/pdf/2015/09/pdf.pdf Craig |
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Mar 13 2015, 02:50 PM
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#12
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Member Group: Members Posts: 495 Joined: 12-February 12 Member No.: 6336 |
At the teleconference Saur corrected this by saying the aurora as seen from the surface would be red. Should probably be more like orange-red/light red, possibly shifted towards yellow or green too. Aha Saur did note that detail also, good of him. And yes you're right, red is to far to the right in the spectrum. If it strong enough to see with the naked eye, such aurora would be orange-yellow or pink. |
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Mar 13 2015, 06:31 PM
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#13
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Member Group: Members Posts: 362 Joined: 13-April 06 From: Malta Member No.: 741 |
The first ever pictures of Ganymede taken by the Voyagers,it was evident there had been tectonic activity. Would a subsurface ocean of liquid water give rise to some form of plate tectonics as on Earth?
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Mar 15 2015, 11:22 AM
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#14
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Member Group: Members Posts: 315 Joined: 1-October 06 Member No.: 1206 |
Slightly tangential question, but do we have any idea how much protection Ganymede's magnetosphere would provide from Jupiter's magnetosphere for future explorers? I'm thinking particularly about the regions near the equator within closed field lines.
P |
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Mar 15 2015, 12:00 PM
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#15
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Junior Member Group: Members Posts: 41 Joined: 11-April 07 From: London, U.K. Member No.: 1957 |
And yes you're right, red is to far to the right in the spectrum. Right, left??? Which way around depends on whether you plot wavelength or frequency on the horizontal axis, and even then if you choose to plot values in ascending or descending order. Maybe we should stick to SI units rather than an entirely anthropocentric reference frame. Would a subsurface ocean of liquid water give rise to some form of plate tectonics as on Earth? The low-pressure form of water ice is always less dense than liquid water, regardless of temperature, so cannot founder into the subsurface as cold oceanic slabs do into the Earth's mantle. |
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