Starship Asterisk*

A Dust Jet from the Surface of Comet 67P

Explanation: Where do comet tails come from? There are no obvious places on the nuclei of comets from which the jets that create comet tails emanate. In 2016, though, ESA's Rosetta spacecraft not only imaged a jet emerging from Comet 67P/Churyumov-Gerasimenko, but flew right through it. Featured is a telling picture showing a bright plume emerging from a small circular dip bounded on one side by a 10-meter high wall. Analyses of Rosetta data show that the jet was composed of both dust and water-ice. The rugged but otherwise unremarkable terrain indicates that something likely happened far under the porous surface to create the plume. This image was taken about two months before Rosetta's mission ended with a controlled impact onto Comet 67P's surface.

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This black and white photos of a small rocky body in the Solar System sure has something extra to offer:A (small) cometary outburst in process!

The plume from Comet 67P reminds me of dust devils on Mars: Small rocky planets or tiny rocky comets suddenly display "life", or at least certainly motion, on their surfaces.


A dust devil is utterly different from a jet. I know, I know. But still.

Today's APOD also makes me think of Comet Holmes.

Wikipedia wrote:

Comet Holmes /ˈhoʊmz/ (official designation: 17P/Holmes) is a periodic comet in the Solar System, discovered by the British amateur astronomer Edwin Holmes on November 6, 1892. Although normally a very faint object, Holmes became notable during its October 2007 return when it temporarily brightened by a factor of a million, in what was the largest known outburst by a comet, and became visible to the naked eye. It also briefly became the largest object in the Solar System, as its coma (the thin dissipating dust ball around the comet) expanded to a diameter greater than that of the Sun (although its mass remained minuscule).

The jet that set off the humongous Comet Holmes brightening would have been something to see!!!

Ann

Ann wrote: ↑Sun Nov 26, 2023 6:52 am

A Dust Jet from the Surface of Comet 67P. Image Credit: ESA, Rosetta, MPS, OSIRIS; UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

---

This black and white photos of a small rocky body in the Solar System sure has something extra to offer:A (small) cometary outburst in process!
...
Ann

It doesn't surprise me that comets come under "stress" as they get closer to the sun. But that jets suddenly appear with great force (can formally “explode”) remains inexplicable to me. The question also arises as to how strong "superjets" should be able to lead to deviating and unpredictable flight paths.
https://www.esa.int/ESA_Multimedia/I ... _Animation

Jac

I should have compared the dust jet of Comet 67P with the water jets of Enceladus.


Is there any sort of similarity between the jets of a comet and the jets of Enceladus?

Ann

Ann wrote: ↑Sun Nov 26, 2023 6:52 am Today's APOD also makes me think of Comet Holmes.

The jet that set off the humongous Comet Holmes brightening would have been something to see!!! :shock:

We have another periodic comet approaching, 12P/Pons-Brooks, that is showing this kind of violent surface activity, and could possibly end up being similar to Holmes. Lots of eyes following it now.

AVAO wrote: ↑Sun Nov 26, 2023 10:25 am
It doesn't surprise me that comets come under "stress" as they get closer to the sun. But that jets suddenly appear with great force (can formally “explode”) remains inexplicable to me.

It seems reasonable that pockets of frozen gas will increase in pressure as they warm, until a fracture occurs in the encapsulating material, resulting in a near instantaneous release of gas and debris.

The question also arises as to how strong "superjets" should be able to lead to deviating and unpredictable flight paths.

What question?

The remarkable thing about that picture is not the bright little squirt - what do geologists say about all that layered rock?

Roy wrote: ↑Sun Nov 26, 2023 6:45 pm The remarkable thing about that picture is not the bright little squirt - what do geologists say about all that layered rock?

Well, as a small "rubble pile" that formed by the accretion of smaller bodies, that surface seems pretty reasonable.

Let us define COMET -

Cosmos
Of
Master Melvyn M. Lusterio is
Eternally Expanding for
Triumphal Tiptop Technology

MelvzLuster wrote: ↑Sun Nov 26, 2023 7:13 pm Let us define COMET -

Cosmos
Of
Master Melvyn M. Lusterio is
Eternally Expanding for
Triumphal Tiptop Technology

Makes your teeth turn green? Tastes like Listerine? Makes you vomit?

Chris Peterson wrote: ↑Sun Nov 26, 2023 6:51 pm

Roy wrote: ↑Sun Nov 26, 2023 6:45 pm The remarkable thing about that picture is not the bright little squirt - what do geologists say about all that layered rock?

Well, as a small "rubble pile" that formed by the accretion of smaller bodies, that surface seems pretty reasonable.

ESA accumulated 400,000 pictures of 67P. They put together a video, “The Comet” which can be seen on YouTube. You have to pause the video quite often to get a sense of different parts. It may be a number of pieces agglomerated together, but where does that (millions of tons) “rubble” come from? Do no geologists look at this? Are there any at ESA?

Roy wrote: ↑Sun Nov 26, 2023 8:37 pm

Chris Peterson wrote: ↑Sun Nov 26, 2023 6:51 pm

Roy wrote: ↑Sun Nov 26, 2023 6:45 pm The remarkable thing about that picture is not the bright little squirt - what do geologists say about all that layered rock?

Well, as a small "rubble pile" that formed by the accretion of smaller bodies, that surface seems pretty reasonable.

ESA accumulated 400,000 pictures of 67P. They put together a video, “The Comet” which can be seen on YouTube. You have to pause the video quite often to get a sense of different parts. It may be a number of pieces agglomerated together, but where does that (millions of tons) “rubble” come from? Do no geologists look at this? Are there any at ESA?

There are thousands of papers over decades analyzing the mineralogy of meteorites. Much of what we understand about the formation of the Solar System comes from that. And more recently, we have a huge amount of research on the pristine samples collected by Hyabusa 2 from Ryugu, and we are just beginning with the samples collected by OSIRIS-REx from Bennu. The Ryugu samples have allowed for a very detailed analysis of the formation and history of that body.
_ Nakamura et al., Science, Vol. 379, No. 6634

Chris Peterson wrote: ↑Sun Nov 26, 2023 9:19 pm

Roy wrote: ↑Sun Nov 26, 2023 8:37 pm

Chris Peterson wrote: ↑Sun Nov 26, 2023 6:51 pm

Well, as a small "rubble pile" that formed by the accretion of smaller bodies, that surface seems pretty reasonable.

ESA accumulated 400,000 pictures of 67P. They put together a video, “The Comet” which can be seen on YouTube. You have to pause the video quite often to get a sense of different parts. It may be a number of pieces agglomerated together, but where does that (millions of tons) “rubble” come from? Do no geologists look at this? Are there any at ESA?

There are thousands of papers over decades analyzing the mineralogy of meteorites. Much of what we understand about the formation of the Solar System comes from that. And more recently, we have a huge amount of research on the pristine samples collected by Hyabusa 2 from Ryugu, and we are just beginning with the samples collected by OSIRIS-REx from Bennu. The Ryugu samples have allowed for a very detailed analysis of the formation and history of that body.
_
science.abn8671-fa.jpg
Nakamura et al., Science, Vol. 379, No. 6634

Do those processes adequately explain the smoothly layered area in the low left where it looks like a liquid flowed and reflowed over time. I have no dog in this debate, just curious. Presumably it would most likely be caused by successive periods of melting water ice?

Also, I presume Rosetta crashed on the surface - however controlled that crash was - and is now non-functional, but what of the lander it released before impact? Is Philae still intact and might it someday be able to be contacted again? It does at least have solar panels and a rechargeable battery according to https://en.wikipedia.org/wiki/Philae_(s ... management

johnnydeep wrote: ↑Sun Nov 26, 2023 9:57 pm

Chris Peterson wrote: ↑Sun Nov 26, 2023 9:19 pm

Roy wrote: ↑Sun Nov 26, 2023 8:37 pm

ESA accumulated 400,000 pictures of 67P. They put together a video, “The Comet” which can be seen on YouTube. You have to pause the video quite often to get a sense of different parts. It may be a number of pieces agglomerated together, but where does that (millions of tons) “rubble” come from? Do no geologists look at this? Are there any at ESA?

There are thousands of papers over decades analyzing the mineralogy of meteorites. Much of what we understand about the formation of the Solar System comes from that. And more recently, we have a huge amount of research on the pristine samples collected by Hyabusa 2 from Ryugu, and we are just beginning with the samples collected by OSIRIS-REx from Bennu. The Ryugu samples have allowed for a very detailed analysis of the formation and history of that body.
_
science.abn8671-fa.jpg
Nakamura et al., Science, Vol. 379, No. 6634

Do those processes adequately explain the smoothly layered area in the low left where it looks like a liquid flowed and reflowed over time. I have no dog in this debate, just curious. Presumably it would most likely be caused by successive periods of melting water ice?

No idea. I can't tell what that material even is. But I'm sure there are a number of papers out there that deal with the geomorphology of this comet.

UPDATE: for example: https://academic.oup.com/mnras/article/ ... ogin=false

johnnydeep wrote: ↑Sun Nov 26, 2023 10:08 pm Also, I presume Rosette crashed on the surface - however controlled that crash was - and is now non-functional, but what of the lander it released before impact? Is Philae still intact and might it someday be able to be contacted again? It does at least have solar panels and a rechargeable battery according to https://en.wikipedia.org/wiki/Philae_(s ... management

Rosetta hit hard enough to be badly damaged, and was also commanded to shut itself down (safe mode) on impact. Philae is probably not damaged, but doesn't receive much light for its solar panels even near perihelion, and certainly not when the comet is further away. It's all but certain that its batteries are no longer functional.

Chris Peterson wrote: ↑Sun Nov 26, 2023 10:50 pm

johnnydeep wrote: ↑Sun Nov 26, 2023 9:57 pm

Chris Peterson wrote: ↑Sun Nov 26, 2023 9:19 pm

There are thousands of papers over decades analyzing the mineralogy of meteorites. Much of what we understand about the formation of the Solar System comes from that. And more recently, we have a huge amount of research on the pristine samples collected by Hyabusa 2 from Ryugu, and we are just beginning with the samples collected by OSIRIS-REx from Bennu. The Ryugu samples have allowed for a very detailed analysis of the formation and history of that body.
_
science.abn8671-fa.jpg
Nakamura et al., Science, Vol. 379, No. 6634

Do those processes adequately explain the smoothly layered area in the low left where it looks like a liquid flowed and reflowed over time. I have no dog in this debate, just curious. Presumably it would most likely be caused by successive periods of melting water ice?

No idea. I can't tell what that material even is. But I'm sure there are a number of papers out there that deal with the geomorphology of this comet.

UPDATE: for example: https://academic.oup.com/mnras/article/ ... ogin=false

Thanks for the link! Perhaps this description from the paper could explain those features:

Finally, a type of fluidization or aeolian process could form some
of the smooth plains, where volatile gases are liberated from the
subsurface (Belton & Melosh 2009) or on the surface (Cheng, Lisse
& A’Hearn 2013), mobilizing granular materials on the surface.
Collections of materials transported by flow events could then fill
pre-existing basins. In such a model, we would expect to see large
flow features associated with the smooth plains.

Chris Peterson wrote: ↑Sun Nov 26, 2023 10:53 pm

johnnydeep wrote: ↑Sun Nov 26, 2023 10:08 pm Also, I presume Rosette crashed on the surface - however controlled that crash was - and is now non-functional, but what of the lander it released before impact? Is Philae still intact and might it someday be able to be contacted again? It does at least have solar panels and a rechargeable battery according to https://en.wikipedia.org/wiki/Philae_(s ... management

Rosetta hit hard enough to be badly damaged, and was also commanded to shut itself down (safe mode) on impact. Philae is probably not damaged, but doesn't receive much light for its solar panels even near perihelion, and certainly not when the comet is further away. It's all but certain that its batteries are no longer functional.

Aw, too bad.

Wickipedia shows it to be a “contact binary” with perihelion of 1.21 AU so solar panels might work there. Mass estimated at 10 billion metric tons. Aphelion is 5.7 AU, period is 6.43 years.

Roy wrote: ↑Mon Nov 27, 2023 12:28 am Wickipedia shows it to be a “contact binary” with perihelion of 1.21 AU so solar panels might work there. Mass estimated at 10 billion metric tons. Aphelion is 5.7 AU, period is 6.43 years.

Yes, they were designed to work near perihelion. But not at aphelion, and the batteries are part of the power system, and unlikely to survive years of deep cold. Additionally, Philae is at the bottom of a sort of crack, so not much light reaches it no matter where the comet is in its orbit.