Sol88
Philosopher
- Joined
- Mar 23, 2009
- Messages
- 8,437
Come on guyz! Let's just concede, Sol88 is right, let him write the ultimate model of electric comets.
Cheers mate, I'll make sure you get a mention!
Come on guyz! Let's just concede, Sol88 is right, let him write the ultimate model of electric comets.
Anybody care to have a crack at what Holger Sierks was meaning when he said "the driving of activity is cliffs???
Also when asked a straight forward question he gave answer that sound like a politicians, dodge weave change the question...why? The've been observing these jets for nearly a year and in 3D and they still don't know???
Be pissed if it was my money![]()
Well that only leaves you with "comets and other bodies" and Earth's water never came from a comet so the ONLY viable alternative is other bodies, presumable asteroids (ROCKS).
Whoops seems you have painted yourself into a corner...again![]()
He is exactly saying "OSIRIS has been monitoring the activity of dust jets in order to find their source", Sol88...back to the interesting stuff
Rosetta orbiter science
!Rational, knowledgeable people can understand English...at the jets source, there should be a hole/orifice with sublimating ice present?

Actually it leaves you with the continued and repeated delusion that Earth's water never came from a comet means comets are rocks, Sol88.Well that only leaves you with "comets and other bodies"
So we have a paranoid rant about what a comment sounded like!Anybody care to have a crack at what Holger Sierks was meaning when he said "the driving of activity is cliffs???
He is saying that the most of the jets can be traced to "cliffs"10:01:40
[GVS OF NARROW ANGLE CAMERA COPY AND OSIRIS LAB, MAX PLANCK INSTITUTE FOR SOLAR SYSTEM RESEARCH]
This narrow angle camera at the Max Planck Institute for Solar System Research is exactly the same as the one onboard Rosetta, which recently detected more than a hundred patches of water ice on the comet’s surface. Together with a wide-angled camera, it forms the OSIRIS instrument – a copy is inside this vacuum chamber to test commands. Apart from imaging the surface, OSIRIS has been monitoring the activity of dust jets in order to find their source.
10:02:14
[INSET CLIP: HOLGER SIERKS
PRINCIPAL INVESTIGATOR, OSIRIS INSTRUMENT]
“We see them either at various places either as standing walls, big huge cliffs, often 200m up to 700m these big huge cliffs on back side of the head lobe but we also see many of these upright walls in the pits that have typical diameter of 200m. And so these are the source, the main source region…you can’t rule out flatlands - we also have a few indications of activity in flatlands - but the driving activity is cliffs.”
!Yes, Sol88, we have traced the sources of comet jets on 67P to places that debunk your ignorant and deluded idea that they are electrical discharges from comets made of rock...idiotic image snipped...
.No, Sol88, that meme illustrates your continued mindless support of the ignorant and deluded idea that there are electrical discharges from comets made of rockand I think this meme wraps the whole dirtysnowball theory!!
...idiotic image snipped...
.Well that only leaves you with "comets and other bodies" and Earth's water never came from a comet so the ONLY viable alternative is other bodies, presumable asteroids (ROCKS).
The difference that I think that Rosetta scientists are thinking of is that a flat surface will retain a deeper dust layer than a "cliff". Thus cliffs and pit walls are more exposed to sunlight and the ices that they are made of are more likely to sublimate to form jets.Other than its geometric relationship to a relative radial to the CG of the comet, will someone explain to me the actual difference between a "cliff" and "flat" on a body of that size and mass?
Probably because the cliffs, and the pit walls, are where ice is exposed closer to the surface. Have a look at a cliff. On top you can't see the rock beneath. On the comet it will be covered by dust and organics. That can't settle to the same degree on a cliff face, due to gravity. Have a look at a cliff face. That is where the underlying material is exposed. Same with the pit walls, once enough material has sublimated from beneath to form a pit. Ditto why the boulders that fall off the cliffs show exposed ice.
Because they're made of ice. Not rock, which is ~3.0g cm^3.
Abstract
Observations of the inner coma of Comet 19P/Borrelly with the camera on the Deep Space 1 spacecraft revealed several highly collimated
dust jets emanating from the nucleus. The observed jets can be produced by acceleration of evolved gas from a subsurface cavity through
a narrow orifice to the surface. As long as the cavity is larger than the orifice, the pressure in the cavity will be greater than the ambient
pressure in the coma and the flow from the geyser will be supersonic. The gas flow becomes collimated as the sound speed is approached and
dust entrainment in the gas flow creates the observed jets. Outside the cavity, the expanding gas loses its collimated character, but the density
drops rapidly decoupling the dust and gas, allowing the dust to continue in a collimated beam. The hypothesis proposed here can explain the
jets seen in the inner coma of Comet 1P/Halley as well, and may be a primary mechanism for cometary activity.
2003 Published by Elsevier Inc.
So we have a paranoid rant about what a comment sounded like!
www.esa.int/esatv/content/download/342714/15476782/EbS97722.doc looks like a fuller transcript of the interviews for that short video.
He is saying that the most of the jets can be traced to "cliffs"!
* standing walls drive the jet activity
* big huge cliffs drive the jet activity
* upright walls in the pits drive the jet activity
* flatland's may drive the jet activity
10:02:14
[INSET CLIP: HOLGER SIERKS
PRINCIPAL INVESTIGATOR, OSIRIS INSTRUMENT]
“We see them either at various places either as standing walls, big huge cliffs, often 200m up to 700m these big huge cliffs on back side of the head lobe but we also see many of these upright walls in the pits that have typical diameter of 200m. And so these are the source, the main source region…you can’t rule out flatlands - we also have a few indications of activity in flatlands - but the driving activity is cliffs.”
Yes, Sol88, we have traced the sources of comet jets on 67P to places that debunk your ignorant and deluded idea that they are electrical discharges from comets made of rock.
No high points - low points (flatlands), cliffs and pits!
Well that only leaves you with "comets and other bodies" and Earth's water never came from a comet so the ONLY viable alternative is other bodies, presumable asteroids (ROCKS).
Whoops seems you have painted yourself into a corner...again![]()