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Rosetta Comet Orbiter -** 120 Icy Patches ** Philae Phones Home ** Ceres Fly Over Video ** New Coma Discovery ** Picture MOTHER LODE !

 
Anonymous Coward
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08/19/2014 10:46 AM
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Re: Rosetta Comet Orbiter -** 120 Icy Patches ** Philae Phones Home ** Ceres Fly Over Video ** New Coma Discovery ** Picture MOTHER LODE !
You say science has no way of knowing under what circumstances their electric comet can produce auroras? That's interesting.
 Quoting: BG-Fan


Really ? I said that, would you care to quote me? Of course plasma scientists can work it out they are the ones predicting the auroras.

"But Comet Siding Spring represents an opportunity to observe a natural experiment, in which a perturbation is applied and we can see the response."
 Quoting: BG-Fan


Yeah big woo. Neptune and Pluto were found through perturbation. Hundreds of exo-planets have been discovered through Doppler spectroscopy ( perturbation ). Rosetta used orbital perturbation three times from Earth and once from Mars on its way to 67P, that was a successful experiment.



[link to www.youtube.com]

Perturbation is about all the science and calculating I see concerning the coming possible Martian auroras in this article, that and magical magnetic umbrellas -- seems they have resorted to throwing shit against the wall.
 Quoting: BG-Fan


Babble.

Was going to reply to a few other of your comments, but why bother, seems Nasa's electric asteroid has turned into an electric comet, which was only a matter of time imo -- mainly because of the coming Siding Springs encounter with Mars.
 Quoting: BG-Fan


Right, you should definitely do less drugs, no idea what you are on here.


Rosetta/Philae Mission
-closed data policy limits public access of data for 2 years. Most exciting time for public will be the week surrounding the Philae landing. The rest of the time is basically snoozefest for the public. The overall mission is fantastic accomplishment.
 Quoting: BG-Fan


You want the raw data? What the hell are you going to do with that 1rof1 ESA releases things for the general public pretty much every day about Rosetta. Whether you find them interesting or not IDK. The OSIRIS and NAVCAM images have been phenomenal and within a few days the resolution will have doubled again. The science briefing on arrival day was fascinating and they have continued to update science results. I have not written about everything here yet.

Siding Spring encounter with Mars
-incoming non-periodical will buzz Mars where there are 7 NASA/ESA assets to capture the event.
-not a mission so the data should flow freely, except maybe from MAVEN
-best chance so far to see and study a non-periodical
-being a non-periodical at perhaps its most active phase (near Mars) it should be quite a show
 Quoting: BG-Fan


Well there is no guarantee as to what you will see.

K
BG-Fan

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Re: Rosetta Comet Orbiter -** 120 Icy Patches ** Philae Phones Home ** Ceres Fly Over Video ** New Coma Discovery ** Picture MOTHER LODE !
You want the raw data? What the hell are you going to do with that 1rof1 ESA releases things for the general public pretty much every day about Rosetta. Whether you find them interesting or not IDK. The OSIRIS and NAVCAM images have been phenomenal and within a few days the resolution will have doubled again. The science briefing on arrival day was fascinating and they have continued to update science results. I have not written about everything here yet.


K
 Quoting: K Hall


Images are raw data. 'I want my Rosetta TV and data for free'....lol

Maybe as time passes you can share what you are learning from the Rosetta mission data that is being released concerning comets and our solar system?

Where can one find the science updates? ...thx!
BG-Fan

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Re: Rosetta Comet Orbiter -** 120 Icy Patches ** Philae Phones Home ** Ceres Fly Over Video ** New Coma Discovery ** Picture MOTHER LODE !

Siding Spring encounter with Mars
-incoming non-periodical will buzz Mars where there are 7 NASA/ESA assets to capture the event.
-not a mission so the data should flow freely, except maybe from MAVEN
-best chance so far to see and study a non-periodical
-being a non-periodical at perhaps its most active phase (near Mars) it should be quite a show
 Quoting: BG-Fan


Well there is no guarantee as to what you will see.

K
 Quoting: BG-Fan


No guarantee but it should be a lot better than anything we've seen so far...and you do concede that this is a great opportunity for a suite of science laboratories and orbiters to observe and gather data on a non-periodical?? Right?

Last Edited by Birkeland on 08/19/2014 12:48 PM
BG-Fan

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Re: Rosetta Comet Orbiter -** 120 Icy Patches ** Philae Phones Home ** Ceres Fly Over Video ** New Coma Discovery ** Picture MOTHER LODE !
You say science has no way of knowing under what circumstances their electric comet can produce auroras? That's interesting.
 Quoting: BG-Fan


Really ? I said that, would you care to quote me?
K
 Quoting: K Hall


Another one of them finicky cat dilemma's??

You said:
"BG-Fan, are you seriously telling me that you don't think the electrical and magnetic properties of comets have been studied over the last 150 years. I think you need the kids book of comets or something. 1852 William Swan produced diatomic carbon spectra that matched William Huggin's comet coma spectra, so we have know for at least 152 years that outer comas contain ionised material, please catch up. As to under what circumstances this could or could not cause auroras that is beyond the ability of anyone here to calculate. This McCanney guy is picking up on what JPL were saying over a year and a half ago, RE auroras."


Siding Spring's coma passing through Mars' atmosphere and "sparking" magnetic umbrellas is the circumstance we were discussing..I thought...lol.

uk

....couldn't find the other 19 ESA country flags! But I am becoming an ESA fan.

Last Edited by Birkeland on 08/19/2014 12:01 PM
BG-Fan

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Re: Rosetta Comet Orbiter -** 120 Icy Patches ** Philae Phones Home ** Ceres Fly Over Video ** New Coma Discovery ** Picture MOTHER LODE !
You want the raw data? What the hell are you going to do with that 1rof1 ESA releases things for the general public pretty much every day about Rosetta. Whether you find them interesting or not IDK. The OSIRIS and NAVCAM images have been phenomenal and within a few days the resolution will have doubled again. The science briefing on arrival day was fascinating and they have continued to update science results. I have not written about everything here yet.


K
 Quoting: K Hall


Images are raw data. 'I want my Rosetta TV and data for free'....lol

Maybe as time passes you can share what you are learning from the Rosetta mission data that is being released concerning comets and our solar system?

Where can one find the science updates? ...thx!
 Quoting: BG-Fan


I just visited ESA's Rosetta Blog. Here is one exchange from the blog. Is this the "updates" source that you referred to?
thx

William Frankeberger says
15/08/2014 at 21:58
"When can we get some data? Is the comet solid rock? Was Horst Uwe Keller (Max Planck) correct, that "a comet is not really a 'dirty snowball' "? (What is the data from CONSERT?) Is the ROMAP working yet? What's the albedo of the comet? We heard earlier that the comet was sublimating two glasses of water a second; is it is or is it ain't? But I mean... what is the real data, not theory or assumption or a guess-interpretation. Is there any "interstellar dust"? What minerals are in or on the nucleus?"



emily says:
17/08/2014 at 13:53
"Hi William, we post updates here on the blog when we have them (there were some first detections of dust grains from GIADA last week, for example). Philae lands in November, so we won't have results from e.g. ROMAP & CONSERT until later."

Edit: and news here - rosetta.esa.int

Last Edited by Birkeland on 08/19/2014 03:08 PM
Glutomoto

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Re: Rosetta Comet Orbiter -** 120 Icy Patches ** Philae Phones Home ** Ceres Fly Over Video ** New Coma Discovery ** Picture MOTHER LODE !
Images are raw data. 'I want my Rosetta TV and data for free'....lol

Maybe as time passes you can share what you are learning from the Rosetta mission data that is being released concerning comets and our solar system?

Where can one find the science updates? ...thx!
 Quoting: BG-Fan


RAW data, is not an Image.

A Raw file is…

• not an image file per se (it will require special software to view, though this software is easy to get).
• typically a proprietary format (with the exception of Adobe’s DNG format that isn’t widely used yet).
• at least 8 bits per color – red, green, and blue (12-bits per X,Y location), though most DSLRs record 12-bit color (36-bits per location).
 Quoting: [link to digital-photography-school.com]


The RAW file format is digital photography's equivalent of a negative in film photography: it contains untouched, "raw" pixel information straight from the digital camera's sensor. This is especially so when dealing with data from a spacecraft.
Glutomoto

Many a doctrine is like a window pane. We see truth through it, yet it divides us from truth. K. Gibran
BG-Fan

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Re: Rosetta Comet Orbiter -** 120 Icy Patches ** Philae Phones Home ** Ceres Fly Over Video ** New Coma Discovery ** Picture MOTHER LODE !
Images are raw data. 'I want my Rosetta TV and data for free'....lol

Maybe as time passes you can share what you are learning from the Rosetta mission data that is being released concerning comets and our solar system?

Where can one find the science updates? ...thx!
 Quoting: BG-Fan


RAW data, is not an Image.

A Raw file is…

• not an image file per se (it will require special software to view, though this software is easy to get).
• typically a proprietary format (with the exception of Adobe’s DNG format that isn’t widely used yet).
• at least 8 bits per color – red, green, and blue (12-bits per X,Y location), though most DSLRs record 12-bit color (36-bits per location).
 Quoting: [link to digital-photography-school.com]


The RAW file format is digital photography's equivalent of a negative in film photography: it contains untouched, "raw" pixel information straight from the digital camera's sensor. This is especially so when dealing with data from a spacecraft.
 Quoting: Glutomoto


I saw where some guy on the Rosetta blog said that comets are black, black like a black t-shirt, (which I had heard last year following ISON from the guy that some belittle here who said that Halley when first observed/imaged was one of the darkest things that astronomers had ever seen). This would mean that the images we are seeing on ESA's site from Rosetta are illuminated (or some other photography term). Is that correct?

It also might mean that the lighter spots on 67P don't necessarily mean icy spots. Is that correct also?

[I was kinda using the 'images as raw data' line as a segway to the Dire Straits joke, as I figured they really weren't.]

Thx for the reply as it gave me a chance to ask these ^^ questions!
Anonymous Coward
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Re: Rosetta Comet Orbiter -** 120 Icy Patches ** Philae Phones Home ** Ceres Fly Over Video ** New Coma Discovery ** Picture MOTHER LODE !
You say science has no way of knowing under what circumstances their electric comet can produce auroras? That's interesting.
 Quoting: BG-Fan


Really ? I said that, would you care to quote me?
K
 Quoting: K Hall


As to under what circumstances this could or could not cause auroras that is beyond the ability of anyone here to calculate.

 Quoting: BG-Fan


That's how trolls always expose themselves eventually. You can't help but carry your joke too far. You as supposed to be playing a character that is crazy and ignorant but you forget there is a difference between that and stupid. No one, not even the most deluded on GLP could think that all the worlds plasma physicists ( or even one ) are posting in this thread. No wonder you were posting exactly the same troll posts here as in Dr. Astro's threads.

K
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Re: Rosetta Comet Orbiter -** 120 Icy Patches ** Philae Phones Home ** Ceres Fly Over Video ** New Coma Discovery ** Picture MOTHER LODE !
Here is an irresistible video of comet 67P rotating, it's quite hypnotic.

[link to gfycat.com]

You can use your mouse to zoom in and scroll around, you can also alter the speed.

It was produced from the red green 3d ( anaglyph ) source images from the OSIRIS NAC camera.

[link to blogs.esa.int]

Here is Dr. Brian May's stereograph from earlier.

Thread: Rosetta Comet Orbiter -** 120 Icy Patches ** Philae Phones Home ** Ceres Fly Over Video ** New Coma Discovery ** Picture MOTHER LODE ! (Page 6)

K
BG-Fan

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Re: Rosetta Comet Orbiter -** 120 Icy Patches ** Philae Phones Home ** Ceres Fly Over Video ** New Coma Discovery ** Picture MOTHER LODE !
The scientific method should involve more than defending existing paradigms at all costs.

Surely a cry of burn the heretic or some appeal to the authorities is born of knee-jerk reactions to the idea that a charge separation may be at work in the universe.

"The (Rosetta) mission is exploratory, so the fact things don't yet add up is exciting and hopefully will enhance our scientific horizons, but it will only do this if we question what we see."

Bye-bye
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Re: Rosetta Comet Orbiter -** 120 Icy Patches ** Philae Phones Home ** Ceres Fly Over Video ** New Coma Discovery ** Picture MOTHER LODE !
Time to catch up with the NAVCAM pictures. Here are the high resolution versions.

From the 17th of August.

[link to www.esa.int]


From the 18th of August.

[link to www.esa.int]


From the 19th of August.

[link to www.esa.int]

The good news is that Rosetta is transitioning to a lower orbit. From Sunday, each leg of it's triangular orbit will be only 50km so the resolution of these NAVCAM images should double. Hopefully later today, or tomorrow we should see another high resolution OSIRIS image.

K
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Re: Rosetta Comet Orbiter -** 120 Icy Patches ** Philae Phones Home ** Ceres Fly Over Video ** New Coma Discovery ** Picture MOTHER LODE !
"Space is big. Really big. You just won't believe how vastly, hugely, mind-bogglingly big it is."

If you have kids, have a go at making a scale model of the solar system.

Here is a calculator page to help out.

[link to www.exploratorium.edu]

If you start of with an orange to represent the Sun, then around 8m away you can place a pin head to represent the Earth. Jupiter on this scale is a small pea about 42m away. Make sure you have enough space because Neptune is 1/4 km further out and the outside of the Kuiper belt 1/2 km away.

( edit, just remembered this )
No one has enough time for the tediously accurate map of the Solar system.
[link to joshworth.com]

So what about Rosetta and 67P well first of all how big is Rosetta's body, life size. It's around 3m x 2m x 2m so about the size of this shed.

[link to cdn.worldstores.co.uk (secure)]

Just to remind you what Rosetta looks like, the shed would be the gold coloured box in the middle.

[link to upload.wikimedia.org]

Rosetta has to operate in the darkness out by the orbit of Jupiter so it needs very large solar arrays to catch enough light to power it. Its "wingspan" at 32m is nearly the same as this 737 jet.

[link to glostransporthistory.visit-gloucestershire.co.uk]

The body of comet 67P is around 4km long, this gives you a pretty good idea of scale.

[link to i.imgur.com]

Now if we want to get an idea of how far away 67P is we have to change scale. Luckily there is image of everything on the internet. When 67P was first spotted people likened its shape to that of a rubber duck, so if we shrank the city sized comet 67P down to the size of this duck.

[link to www.tallshipsfestivalla.com]

Rosetta's span would be around 3/4 mm, like a tiny grain of salt. 67P is currently about 410 million km from the Earth. On our rubber duck scale that is the equivalent distance of New York to Beijing or London to Buenos Aires. But Rosetta hasn't travelled directly to 67P, it has gone the long way. Rosetta has travelled 6.4 billion km so far. On our rubber duck scale that is equivalent of the grain of salt travelling four and half times round the Earth's equator.

K
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Re: Rosetta Comet Orbiter -** 120 Icy Patches ** Philae Phones Home ** Ceres Fly Over Video ** New Coma Discovery ** Picture MOTHER LODE !
Could 67P be three times heavier and six times denser than originally thought ? I would say yes.


Yesterday ESA released a very early, preliminary estimate of 67P's mass. You may remember Rosetta has been performing a triangular orbit of 67P ( more of that in a later post ) in order to estimate its mass. The first triangle was completed on the 17th August.

The early estimate for the mass of 67P is

10 trillion kg which is about 11 billion tons ( U.S. )
1E+13kg ( +/- 10% )

[link to blogs.esa.int]

Which is fantastic, but unfortunately there is no early estimate for density, which is quite annoying as that is significant for comet conspiracy theorists on GLP.

So my first though was to do a back of the the envelope type calculation to work out 67P's volume. We have been told that 67P is 4km long and 3.5km tall so taking it to be 2.5km wide we can come up with a number. Subtract a quarter for it being boot shaped and assume 50% of the material that would fill out an L shaped polyhedron is missing and you come up with

13 km^3 - Which is probably too low.

Then I thought I could try and make my own 67P using my kids abandoned plasticine and ESA's shape model, after all that is what the flight dynamics people have been using.

[link to blogs.esa.int]

So I made my own ( yes I know it's backwards and too fat, the final one was slimmed down )

[link to i.imgur.com]

And measured its volume ( displacement ) to represent

19 km^3 - Which is probably on the high side, my model was fat.

So finally I thought comets are basically big lumps or stuff that ablate away to leave a pebble sort of shape. So I took the shape model and pulled apart the frames in GIMP and measured carefully ( assuming it is 4km long ) and treated 67P as two ellipsoids joined by a short cylinder. This time I came up with a figure that I am most confident about.

17 km^3 - Still a little high, it doesn't take into account the concave "foot" of the duck and craters.

I think I will give the very unscientific estimate of 16 km^3 +/-5 ( maximum range based on all my estimates )

Combine this with the mass estimate and we come up with a density of

0.62 g cm-3 with a range of 0.43 to 1 g cm-3

Compare this to other bodies we know about

Earth 5.5 g cm-3
Mars 4
Vesta 3.4
Moon 3.3
[silicate rock] 3
Triton 2
Ceres 2
[ water ice ] 0.9

Seeing as we know 67P contains both silicate rock and water ice it looks probable that 67P contains something else, namely nothing. For 67P's density to be as low as 0.6 g cm-3 then it will also have to contain voids and empty spaces. These may between grains of dust or even be in the form of pockets and larger structures. This is one of the things Rosetta will be investigating over the coming year.

Finally some people on the ESA blog were excited because this mass estimate is three times the estimate that had previously been given ( 3.14E+12 kg ) Taking that as proof of 67P being a rocky electric comet. That estimate comes from this paper.

[link to www.lpi.usra.edu]

Which is a brilliant clever application of what information the authors had on 67P. They came up with an estimated density of 0.1 g cm-3, just one sixth of my estimate. To put that in perspective, the densest aerogels are five times denser, I imagine this is where the "cigarette ash" analogy comes from. I think the Philae landing team will be very happy If I am right and those authors are wrong.

K
KipKat

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08/22/2014 08:36 AM

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Re: Rosetta Comet Orbiter -** 120 Icy Patches ** Philae Phones Home ** Ceres Fly Over Video ** New Coma Discovery ** Picture MOTHER LODE !
Thanks for keeping the thread updated K!

Is it just me or does it look like this thing is going to split in two?
:kkwapper:
Anonymous Coward
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Re: Rosetta Comet Orbiter -** 120 Icy Patches ** Philae Phones Home ** Ceres Fly Over Video ** New Coma Discovery ** Picture MOTHER LODE !
Thanks for keeping the thread updated K!

Is it just me or does it look like this thing is going to split in two?
 Quoting: KipKat


No It's not just you, I think it will become two comets ( again ? ) eventually. I don't know how many passes around the sun that will take. Thursday's NAVCAM picture shows up the two body appearance of 67P .

[link to www.esa.int]

At the moment there are two ideas as to how 67P came to look like this. Firstly it is a contact binary, two comets came together at low speed and fused. Secondly it was always one comet but the neck region had more icy material that ablated away at a faster rate.

K
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Re: Rosetta Comet Orbiter -** 120 Icy Patches ** Philae Phones Home ** Ceres Fly Over Video ** New Coma Discovery ** Picture MOTHER LODE !
I had a look at the volume calculation again after remeasuring the shape model. My new figures ( 20, 18.5, 17.5 ) give a slightly higher volume, but are converging on a figure near 19 km^3.

So using that figure and narrower confidence band I am going to say the density is 0.53 g cm-3 with a range of 0.4 to 0.73 cm-3, so that would rule out the possibility of 67P being solid, it must contain empty spaces in some form ( according to me only, ESA is yet to comment )

So the density predictions so far come from these French scientists. [link to www.lpi.usra.edu] Electric universe, who say that comets are rocky bodies, so I use the figures for dense asteroids and the BBC.

The BBC's science correspondent, Jonathan Amos, has written a piece which is online and on tv text saying that the density is 0.3 g cm-3, which is surprising because it would imply 67P is 33 km^3 in volume, that would imply the 4km long figure we got from ESA was wrong. I don't know if he has had a separate briefing from ESA about the density. [link to www.bbc.co.uk]

Here are the predictions so far:

Electric universe 3.2 - 7.7 g cm-3
Me 0.53 g cm-3
BBC 0.3 g cm-3
French scientists 0.109 g cm-3

K
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Re: Rosetta Comet Orbiter -** 120 Icy Patches ** Philae Phones Home ** Ceres Fly Over Video ** New Coma Discovery ** Picture MOTHER LODE !
ESA operations have updated the information on Rosetta's recent series of manouvres. Firstly with a recap of what happened up to the 17th.

[link to blogs.esa.int]



[link to www.youtube.com (secure)]

Then from the 17th until the 3rd of September.

[link to blogs.esa.int]

Yesterday Rosetta passed within 60 km of 67P's surface. The record for the longest lightning bolt on Earth is an impressive 190 km [link to www.lightningsafety.com]

K
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Re: Rosetta Comet Orbiter -** 120 Icy Patches ** Philae Phones Home ** Ceres Fly Over Video ** New Coma Discovery ** Picture MOTHER LODE !
Today the ESA Rosetta team will be selecting five candidate landing sites for the Philae lander. They should announce the sites tomorrow. The final site selection comes in October for a landing in November.

The choice of site is determined firstly by the question, is it safe and technically feasible to land at the site. Other factors that will be considered are: can Rosetta stay in contact with Philae at the site, Does it have a mixture of day and night and is the surface interesting scientifically.

There is a short video from the very earliest view of candidate landing sites, they are marked with green ovals. The actual accuracy of landing is no better than 600m. Philae will be unguided and unpowered on the way down.



[link to www.youtube.com (secure)]

Here is the much more complete ESA arcticle on landing site selection.

[link to blogs.esa.int]

K
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Re: Rosetta Comet Orbiter -** 120 Icy Patches ** Philae Phones Home ** Ceres Fly Over Video ** New Coma Discovery ** Picture MOTHER LODE !
Here is the longer version of the landing site selection process.

[link to sci.esa.int]

With an animation of Philae landing and starting its science mission. Unfortunately there is no commentary on this vid.



[link to www.youtube.com (secure)]

Here is some description to go with the above video.

The animation begins with the deployment of Philae from Rosetta at comet 67P/Churyumov–Gerasimenko in November 2014. Rosetta will come to within about 10 km of the nucleus to deploy Philae, which will take several hours to reach the surface. Because of the comet’s extremely low gravity, landing gear will absorb the small forces of landing while ice screws in the probe’s feet and a harpoon system will lock the probe to the surface. At the same time a thruster on top of the lander will push it down to counteract the impulse of the harpoon imparted in the opposite direction. Once it is anchored to the comet, the lander will begin its primary science mission, based on its 64-hour initial battery lifetime. The animation then shows five of Philae’s 10 instruments in action: CIVA, ROLIS, SD2, MUPUS and APXS.

K
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Re: Rosetta Comet Orbiter -** 120 Icy Patches ** Philae Phones Home ** Ceres Fly Over Video ** New Coma Discovery ** Picture MOTHER LODE !
Here is the NAVCAM picture from the 22nd

[link to www.esa.int]

All the instruments on Rosetta, like NAVCAM, are competing with each other for electrical power and bandwidth to send their data back to ESA. Rosetta has a power budget of around 800 watts to power everything on board, that's not enough to power a hairdryer.

Communication rates back to ESA vary between 10 Kbit/s and 22 Kbit/s , but communication is often not possible. If you started using the internet in the late 90s that is around the same speed as your dial up modem used to be.

[link to www.esa.int]

K
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Re: Rosetta Comet Orbiter -** 120 Icy Patches ** Philae Phones Home ** Ceres Fly Over Video ** New Coma Discovery ** Picture MOTHER LODE !
Well the five candidate landing sites have been chosen from ten possible sites. Here they are on a map of the comet.

[link to www.esa.int]

Three of the sites are on the head of the duck. One interesting site is site B. That is the "engine" or "crater of doom" or "entrance to the interior" depending on which idea you like. Here is picture showing crater B in its most doomy look, on the right in this image.

[link to www.esa.int]

We have discussed this deep crater before and why shadows on 67P easily make crater floors disappear.

Here is the in depth analysis of landing site selection with some more nice images.

[link to www.esa.int]

The landing site selection has been more problematic than they imagined when Rosetta was launched due to 67P's complex shape, rotation and differences in expected surface composition.

K
TheWatcher-Anonymous Hero

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Re: Rosetta Comet Orbiter -** 120 Icy Patches ** Philae Phones Home ** Ceres Fly Over Video ** New Coma Discovery ** Picture MOTHER LODE !
Thanks for the updates.
Going to be a long wait until November.

Are they landing on a solid surface?
Anonymous Coward
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Re: Rosetta Comet Orbiter -** 120 Icy Patches ** Philae Phones Home ** Ceres Fly Over Video ** New Coma Discovery ** Picture MOTHER LODE !
Thanks for the updates.
Going to be a long wait until November.

Are they landing on a solid surface?
 Quoting: TheWatcher-Anonymous Hero


That's the billion euro question. The images from the OSIRIS NAC show that large areas of the comet seem to be blanketed in dust ( regolith ). I guess that shouldn't have been a surprise because that was what Whipple was predicting in his 1950 paper on Enke. You can see what appear to be boulders at the candidate landing site, that would suggest that maybe the dust layer is not too thick at these points.

Philae was designed to land on an icy surface so it has a number of features to help anchor it on such a surface. Firstly it has a cold gas system. This is a brief jet of gas which is fired out from the top of Philea when it lands, its purpose is to stop Philae rebounding off the surface. It has two mini harpoons that fire into the surface to help anchor it and each of its three small pairs of footpads is equipped with an icescrew that tries to screw itself into the surface.

Clearly none of these features or the small footpads are going to work very well on a dusty surface. My last calculation for 67P's bulk density puts it in the same region as snow, although that does not say anything about the mechanical strength or cohesiveness of the surface.

Here is what ESA was hoping would happen.



[link to www.youtube.com (secure)]

K
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Re: Rosetta Comet Orbiter -** 120 Icy Patches ** Philae Phones Home ** Ceres Fly Over Video ** New Coma Discovery ** Picture MOTHER LODE !
So what's with all this ancient Egypt stuff ?

This week the Rosetta orbiter has climed to the second step on its pyramid orbit [link to blogs.esa.int] of the Sphinx comet [link to www.thedailybeast.com] , time for a rundown of ancient Egyptian links.

Rosetta refers to the Rosetta stone. This is a granite slab with an inscription in three ancient languages, found in the town of Rosetta ( Rashid ) in the Nile delta by Napoleon's army. The stone provided the key to reading the previously undecipherable Egyptian hieroglyphics. It was left to the brilliant French philologist, Jean-François Champollion, to decipher it and for the first time in centuries be able to understand hieroglyphics. Here is a short version of how he did it.



[link to www.youtube.com]

You can watch the longer version from 9 minutes in episode 12 of Carl Sagan's cosmos.

The intention of the Rosetta mission is to unlock the secrets of the early solar system by studying comet 67P, just as the Rosetta stone helped to unlock the secrets of ancient Egypt.

Rosetta ( orbiter ): Named after the town ( Rashid in Arabic ) where the Rosetta stone was found. [link to cdn.roughguides.com]

Philae
( lander ): The island in the Nile where an obelisk was discovered that had an inscription which helped to decipher the Rosetta stone. [link to en.wikipedia.org]

Ptolemy
( a Philae instrument ): The name of the first Helenistic king of Egypt and his dynasty. His name was one of the keys to deciphering the Rosetta stone.

Berenice
( a cancelled Rosetta instrument ): The wife of Ptolemy I ( Berenice and Ptolemy were to be identical instruments )

Now we get into acronyms. Scientists and engineers love mangling acronyms to make relevant words.

OSIRIS
( Optical, Spectroscopic, and Infrared Remote Imaging System ) Osiris was the Egyptian god of the underworld and the dead. The OSIRIS team have a neat logo they put on their software and documents, which apparently means the eye of god. [link to www.enterprisemission.com]

SESAME ( Surface Electrical, Seismic and Acoustic Monitoring Experiments) Sesame, pretty essential in Egyptian cooking.

MIDAS (Micro-Imaging Dust Analysis System) Midas was an ancient king of Phrygia, so not really then.

Here are a couple of pages listing the instrument names, if you find any other Egyptian links please post them here, thanks.

[link to en.wikipedia.org]

[link to en.wikipedia.org]


K
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Re: Rosetta Comet Orbiter -** 120 Icy Patches ** Philae Phones Home ** Ceres Fly Over Video ** New Coma Discovery ** Picture MOTHER LODE !
The instrument ALICE doesn't stand for anything BTW, it's just a name that the principle investigator likes, according to JPL.

A couple of funny acronyms I like. In Britain, during times of national emergency like the Iraq crisis or last winter's Ashes series, the government meets in a COBRA meeting. This makes it sound like they are all sitting around in superhero costumes. COBRA actually stands for cabinet office briefing room A, so actually it's a meeting room in the heart of Whitehall's bureaucratic home. There is some suggestion that originally it was just called briefing room A, but BRA was not thought to be macho enough.

The winner, however is NASA ( National Acronym Slingers Association ) with the Ka-Band Objects Observation and Monitoring or

*** KaBOOM ***


How about that.

[link to www.universetoday.com]

K
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Re: Rosetta Comet Orbiter -** 120 Icy Patches ** Philae Phones Home ** Ceres Fly Over Video ** New Coma Discovery ** Picture MOTHER LODE !
ESA are highlighting Rosetta's dance through the inner solar system with their simulator. As before you can use the slider to view Rosetta at any time in the mission and use your scroll wheel to zoom in and out.

[link to sci.esa.int]

K
KipKat

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08/28/2014 05:58 AM

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Re: Rosetta Comet Orbiter -** 120 Icy Patches ** Philae Phones Home ** Ceres Fly Over Video ** New Coma Discovery ** Picture MOTHER LODE !
Keep up the good work with your updates K, thanks!

clappa
:kkwapper:
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Re: Rosetta Comet Orbiter -** 120 Icy Patches ** Philae Phones Home ** Ceres Fly Over Video ** New Coma Discovery ** Picture MOTHER LODE !
Keep up the good work with your updates K, thanks!

clappa
 Quoting: KipKat


And thank you! When I started this thread I thought it would be just one or two updates a week until the landing. It's been busier than I thought. I am sure it will be quieter at times though. The mission scientist ( who is a plasma physicist ) says for him the mission will not really get going until January next year and perihelion is not until almost this time next year, so there is a long way to go.

Here is the latest NAVCAM picture.

[link to www.esa.int]

Rosetta is now so close that it can't fit all of 67P into one NAVCAM frame, so they are now taking four NAVCAM shots to cover the whole comet. That means all the shadows and lighting will be different in each quarter of the picture. That could lead to its own conspiracy theory!

[link to blogs.esa.int]

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Re: Rosetta Comet Orbiter -** 120 Icy Patches ** Philae Phones Home ** Ceres Fly Over Video ** New Coma Discovery ** Picture MOTHER LODE !
Keep up the good work with your updates K, thanks!

clappa
 Quoting: KipKat


The mission scientist ( who is a plasma physicist ) says for him the mission will not really get going until January next year and perihelion is not until almost this time next year, so there is a long way to go.

K
 Quoting: K Hall


Just curious, is January when it starts outgassing?
Why is a Plasma physicist on the Team?
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Re: Rosetta Comet Orbiter -** 120 Icy Patches ** Philae Phones Home ** Ceres Fly Over Video ** New Coma Discovery ** Picture MOTHER LODE !
Just curious, is January when it starts outgassing?

 Quoting: TheWatcher-Anonymous Hero


Hi The Watcher, comets start outgassing when they pass the frost line. That is the imaginary line in the solar system where there is enough energy from the Sun to start turning the comet ices into gas. In the Solar system that is thought to be around 5 AU, where the Sun can heat a comet ( or other body ) to around 150 K ( -123 C). Long period comets that have never visited the inner Solar system before are thought to have more ices that sublimate at low temperatures like CO ( carbon monoxide ) and CO2 ( carbon dioxide ). Short period comets like 67P have a higher proportion of water ice that sublimates at a higher temperature, having exhausted more of their low temperature volatiles.

Strangest substance - water : Thread: Rosetta Comet Orbiter -** 120 Icy Patches ** Philae Phones Home ** Ceres Fly Over Video ** New Coma Discovery ** Picture MOTHER LODE ! (Page 2)

You can see on this phase diagram that CO2 sublimates at a lower temperature than water.

[link to en.wikipedia.org]

In a vacuum around 150K ( -123 C ) against water 203K ( -70C )

So as soon as 67P got close enough to the Sun ( around 4 AU ) Rosetta started to detect water production, not much at first, but the amount will grow all the time now. What has started as a trickle will turn into a torrent.

[link to www.esa.int]

Hopefully we will see plumes like on comet Hartley 2

[link to epoxi.umd.edu]

We are already seeing 67P develop a faint coma

[link to sci.esa.int]

[link to astrobob.areavoices.com]

Perihelion is next August, so it is a case of improving production until then. This November was selected as a landing date partly because they wanted Philae to land before the comet got really active.

K





GLP