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gcecil
QUOTE (volcanopele @ Jan 15 2008, 09:34 PM) *
Here are some labeled, sharpened, and comparison images (with Mariner 10 and RADAR):


The bright crater pair just to the left of the C in Caloris is the brightest albedo feature in our ground-based images of this hemisphere. We suggested the name "Mistral" for it, after Gabriella Mistral (Chilean Nobel prize in literature). Up to the IAU of course (but we did see it first smile.gif

The dark region left of this extending up from middle of image to terminator at 11 oclock is also striking in our ground images, see my post #79 in the Radar & Mariner 10 thread.

Agreement with rayed radar craters (and their diameters) is given in our paper.
gndonald
QUOTE (JJR2 @ Jan 16 2008, 10:29 AM) *
Yep...that's a picture.


That is indeed, and it's replacing my current wallpaper (an Apollo montage), it'll be interesting to see just how many people mistake this for the Moon (and believe me it will happen).
Holder of the Two Leashes
QUOTE (volcanopele @ Jan 15 2008, 08:34 PM) *
Here are some labeled, sharpened, and comparison images (with Mariner 10 and RADAR):


Excellent! Thank you.

While Caloris appears more subdued here than in the Mariner images, it also appears rather more interesting, with that mix of both dark and light craters.
tedstryk
I applied similar enhancements to this image as I did the opnavs.

Click to view attachment
gcecil
This image Click to view attachment (bigger view here) is a quick comparison with my ground-based SOAR images. Not highlighted but obvious is the dark area across the top half of the right-hand ground-based image and upper right-hand part of left-hand image. We show in our paper (link in #251 above) that the dark region extends around the right-hand limb into the Mariner 10 hemisphere. A striking asymmetry, whose mineralogy the multi-color wide-field images will presumably constrain. The ground-based image at left shows how amazingly bright some of the craters near the MESSENGER terminator get in high sun.
nprev
Those craters in the northern hemisphere with bright interiors/dark exteriors--or vice versa--are really striking. Why do I sense unexpected minerological complexity...?
Steve G
I've been looking at the icy moons of Jupiter and Saturn so long I had nearly forgotten what good old fashion rock is. I admit, I am quite crestfallen over Caloris. What a let down!

When it comes down to it, I think our moon is the most aesthetic and interesting satellite up there.
JRehling
[...]
Astro0
Data still streaming in at Canberra DSN.
Extended tracking time until 0725 UTC on the 70-metre and then switching over to one of the 34-metre antennas through to 1000 UTC. Current rate: 25-30 kb per hour. Suspect that this will slow down a bit once we transfer to the 34-metre.
The extended tracking time should allow the majority of data from Messenger to come down.
We did have a short 5 minute break in data due bad weather and will have to pick that up on a second pass.

Hope you'll all enjoy the should that's on the way!
Astro0
JRehling
[...]
dvandorn
QUOTE (Astro0 @ Jan 16 2008, 12:38 AM) *
Current rate: 25-30 kb per hour.

Umm... 25 to 30 kilobits per hour? At that rate, wouldn't it take about 40 hours to receive a kilobyte?

Just how compressed is this data?

-the other Doug
edstrick
I ran bandpass filtering on the full disc image. I didn't have to do insane polar projection filtering as I did on the approach images.
The result flattens limb to terminator shading, boosts "mesoscale" albedo markings and provides some sharpening. I'm attaching 2 versions. one, xxxx-2x was filtered with zero and one-level pixel data excluded to avoid ringing artifacts at the bright limb. I've enlarged it 2x in photoslop so you can zoom in on details without them pixelizing. The other included zero and 1 level pixels, has terrible artifacts at the bright limb, but has more contrast than the first and can show a trace (not much, it turns out) of the faintest pixels at the terminator.
n1ckdrake
QUOTE (dvandorn @ Jan 16 2008, 02:38 AM) *
Umm... 25 to 30 kilobits per hour? At that rate, wouldn't it take about 40 hours to receive a kilobyte?

-the other Doug


I think Astro0 meant 25 to 30 Kilobytes per hour. IIRC the downlink capability at higher data rates averaging 9 kilobits per second.
edstrick
One additional file before an assortment of comments.

Attached is a segment of the bandpass enhanced global image. A rather well defined area of so far un-mentioned (i think) darker terrain north of Caloris is approximately identified by an outline of red dots. Compare with the other image to see the details of the edge of this feature.

Comments. 1.) Satellite Search. After Mariner 10 flew past on it's first encounter, there was a frenzied flurry of activity when the ultraviolet spectrometer team thought they'd identified an object moving near Mercury, triggering a hastily planned satellite search with the imaging cameras (and probably replacing some more valuable intermediate resolution imagery, possibly full disc color coverage or something. It turned out that they'd spotted a far-UV bright star, and the planet was moving RELATIVE TO the star, due to spacecraft flyby motion and Mercury's rapid solar orbit. Similar frienzied discussion of the possibility of stable orbits around Mercury ensued. I'm getting deja vue all over again, double-dose.

2.) Concentric Double craters: They're common on Mercury. Mariner 10 mapped quiet a few of these objects that are transitional to multi-ring basins. You also get peak-ring craters where the central peak forms an incipient ring. The higher gravity on Mercury changes the proportions of scaling laws so they occur for smaller crater sizes than on the Moon, and there's just more surface area on Mercury to host them, so they're fairly common.

3.) It's bland, and kinda ugly. The overall blandness is much like the Mariner 10 departure hemisphere, and (without the postage-stamp mosaic pattern of all versions of that image till the recent one here), resembles the recently re-shown Mariner 10 second encounter Wide Angle image, which for 3 decades, I've thought of as the "moldy orange" image. It does resemble Callisto (without bright crater palimpsests) and Oberon. Mercury has no lava plains that are minerologically grossly distinct from the cratered terrain, unlike the Moon, so eruptive plains are very hard to recognize except on the basis of morphology. Mercury all ***LOOKS*** like Lunar Highlands, and the gross minerology may indeed be similar, but there's stuff going on (as the new image indicates) we only saw traces of in Meriner data. Kinda ugly? "Face only a mother Sol would love!"

4.) The relief is low, the limb is smooth. Yes. It's bigger than the moon, so even if the relief was the same, it would look less in a full disc image. And the bigger gravity makes it harder to build a pile of rubble as high as on the Moon. And at about 10 km per pixel.... strong relief is only visible near the terminator where the low sun lets you see it. Higher resolution images will far, far better show relief at higher sun angles than this image does.

5.) Mariner 10 saw the nothern lattitudes had abundant intercrater plains and cratered plains. This continues to the terminator here, in patches. The southern region seems to continue to have much less plains. Near the terminator, at low latitudes, yes, there's something interesting going on, with hints of buried structures under the plains and ridges, and alignments of features that make me wonder if there's something more interesting just beyond the terminator, though it's old, whatever it is.

6) Mozart crater's a disappointment at high sun. Very bland. Tolstoj, however is going to be very interesting in multispectral data. Don't necessarily expect it's dark outer zone to be the same as the random dark mottles elsewhere on the disc, the dark crater features within Caloris, or the dark half-ring in the terrain north of Caloris i'm "pointering" to at the top of this post.

7) Dark Odds and ends. Numerous small dark ray craters and dark splotch craters are visible here and there. They were studied in Meriner 10 data with suggestions relative to comet impacts or carbonaceous chondrite impacts or I can't remember what. I think there were suggestions toward conclusions, but no strong conclusions. There are regions of patchy dark material, mostly between bright crater rays and splotches that would obscure them, that appear to be darker than just a lack of bright rays and splatter and splotches imply. There's a scattering of them below image center, one vaguely kidney bean shaped, and more left of image center. Colorimetric pecularities of lack of such may tell us to be more or less interested in them. The dark crater materisl in Caloris mostly avoid the outer 20% of the basin diameter. Igneous fill may be deeper there, while the dark features may excavatle deeper crustal material exposed or nearer to the surface in uplifted "Apennine bench like" inner basin ring matierials.

8) Bright oddities. Mariner 10 saw some craters with seemingly anomalous bright material inward of the crater walls, where normal crater floor and central peak material would be. A small crater at 9:00 and another at 11:30 clock angle within Caloris, both with darker rims and close-in ramparts, have bright features. The peak-ring crater, reported in Radar, seems to have brighter than expected peaks in the ring. The double-ring impact basin to the north seems to have decidedly bright peaks in it's ring. Here and there other "interesting" bright features appear that are wiped out by the agressive contrast stretch of the enhanced image.

It will be very intersting to see how different bright materials and different dark materials sort out into classes based on multispectral data. THEN, once we get into orbit, it will be very interesting to see how that mineralogically and physical-properties driven geolgoy correlates with elemental abundances derived from X-ray and Gamma data.

What I'd really like to see is a spectral model based "decomposition" of a global lunar map into spectral classes of 1.) impact glasses, and 2.) non-glassy mineral components. The same could be done to Mercury, based first on color mapping, then with spectroscopid <UV and IR> data added. Lunar and Mercurian surface materials visible in sunlight consist of regolith and rock, which are mixtures of impact <and some volcanic> glass, and mineral fragments. The mineral fragments, when they make up enough of the total population in a pixel, show discrete spectral features that identify some of the minerals present. The glasses behave differently, lacking sharp diagnostic features, but showing colors diagnostic of things like titanium <ilmenite> content and surface "maturity" They're normally presented in one map, mixing varieties of apples and varieties of oranges. I want a pair of maps, showing (where anything is showable -- some areas will be left blank in each map) mineral variety and glass variety data. This might make much more sense of Mercury multispectral data of this moldy orange than we can with monochrome or simple color classifications of surface units.
volcanopele
Well, it is almost time for me to go to sleep, but I wanted to address one of the more interesting features seen in this new image of Mercury: the dark halo (or dark floored) craters, particularly those in Caloris Planitia. Makes me wonder if these craters punched into some iron-rich basalt layer (most of the surface of Mercury IIRC, is supposed to be iron-poor). The distribution certainly suggests that some areas had this darker material at or near the surface while others did not.

It isn't as simple as dark-halo craters mapping to smooth plains areas, is it? Obviously, the terrain west of Caloris counts as smooth plains, but hardly a dark halo/floor crater to be found...
edstrick
Rather than "iron rich basalt", I'm thinking of iron-rich deeper crustal rocks, like those exposed in the S. Polar/Aitkin (We REALLY need to have it named Shoemaker) basin on the Moon. Much of the Mariner-10 visible floor of Caloris is smooth plains, so it appears that the original basin floor was covered by some sort of melt, but it's not lunar-mare dark, so it's either built up a thick dusting of average Mercurian crud to lighten it (I really doubt that), or is a low-iron melt, not that dramatically (or at least visibly) chemically distinct from other Mercurian plains and highlands.

All this makes the very odd dark materials of the Tolstoj basin all the odder, as other medium-large basins (seen by Mariner) don't obviously show something like that, and you'd expect Caloris would show it even more. Maybe there was something INTERESTING at intermediate crustal depth at Tolstoj that other basins didn't dig into as it wasn't present where they hit.
jasedm
Speaking of Shoemaker, is it reasonable to expect to see any Catenae in some of the higher-res images?
Intuitively, I'd expect Mercury to have comparable numbers to the Galilean moons, but don't remember seeing any in Mariner images.
edstrick
I think given the average "more chewed up" nature of the younger terrains on Mercury as Mariner 10 saw them, such features will be less obvious. Relative to some normalized cratering model, Mercury's young terrains are older than Moons, more like Caley Plains than Mare Imbrium. Catenae are rather small features, also. Km and better resolution data from Mariner were a small fraction of the total coverage, and low sun angle data a portion of that (though they did not waste high rez images in high-sun no shadowing areas)

Also, something you can see: Large craters/small basins have a dense peppering of secondary immediately next to them due to the sorter ranges of secondary crater forming ejecta in Mercury's high gravity, compared with the moon.
t_oner
Here is a quick projection of edstrick's filtered image (without any knowledge of the image geometry).
Astro0
'n1ckdrake' - I think Astro0 meant 25 to 30 Kilobytes per hour.

Correct Kilobytes. Allowing for glitches, around 7 hours of downlink time. A few repeat passes through the DSN may be needed to get everything cleanly.

The tracking pass at the Canberra DSN finished about an hour ago, and went very well from our point of view. I don't have any figures as to the total of data received, that will be up to the mission teams to let us know. Still even with this one new image, it has kept lots of people on UMSF very busy...can't wait to see the other 1,212 images.

Enjoy
Astro0
peter59
QUOTE (Astro0 @ Jan 16 2008, 11:37 AM) *
'n1ckdrake' - I think Astro0 meant 25 to 30 Kilobytes per hour.

Correct Kilobytes.


25-30 Kilobytes per hour? Are you sure? Rather 25-30 Kilobytes per second.
Bjorn Jonsson
25-30 kilobits per second (kbps) seems likely. Downlink bandwidth is usually given as kbps and 25-30 kbps is comparable to various inner solar system spacecraft. It would be nice to know for sure the correct value though.
ugordan
Even 25 kbps sounds like a rather low bandwidth for inner solar system standards. Granted, MESSENGER doesn't use a dish antenna, but still - Cassini can get over 100 kbps from 9 AU away.
Ant103
What extraordinary times we're living smile.gif

If you want, I have made a desktop version of the last pic Messenger send us.
djellison
QUOTE (ugordan @ Jan 16 2008, 11:12 AM) *
Even 25 kbps sounds like a rather low bandwidth for inner solar system standards.


No - Messenger really is quite a low data rate mission. Cassini has a great big HGA. Messenger doesn't.

Doug
ugordan
I guess that's a Discovery class imposed weight limitation. It's expected that MESSENGER will, on average, get up to 80 full resolution images per day once in orbit. This is based on onboard compression speed and mission requirements (which I guess are greatly affected by available bandwidth).

It's remarkable how tight the point spread function of the wide angle camera is, it looks tighter than 1 pixel. In fact, it almost looks like it's causing some aliasing and the WAC images certainly don't need any sharpening applied like the NAC images do. WAC is a great context camera, one of the sharpest imagers I've seen; look at the sharpness of small craters near the terminator. Can't wait to see the color version of the above image.
Oersted
Marvellous images: what a great age to live in!
dvandorn
OK -- 30 kilobits per second, I can see. At 30 kilobytes per hour, you would be getting about 210 kilobytes over seven hours, and even the jpeg'ed images we've already seen are larger than that. Each.

Unless there is some kind of uber-compression going on here of which I'm not aware, I would think it would be hard to fit 1,200 images into a file only 210 KB large.

-the other Doug
robspace54
When I was a mere boy, Mariner 4 flew past Mars and sent it's fuzzy, smearing 22 photos of Mars back at the rate of 8 1/3 bits per second!!!! That makes 25 kilobits per hour sound high, but the effective bit rate is less than 7 bits per second... In this age of digital instant gratification waiting is not something we like to do.

I am really enjoying the "instant science" here. It reminds me of the Pioneer and Voyager flybys. :-)


Rob
tedstryk
Galileo made us forget how much the internet had advanced things, since it was often months before the data was on the ground.
David
Would anybody like to have some fun matching the new image to this old-style telescopic albedo map from the early 20th century?
Phil Stooke
Good luck! Unfortunately, Antoniadi and all astronomers of the time thought Mercury was tidally locked to the sun. That's why his map shows just one side. It's really a composite of all 360 degrees compressed into 180. Every time Antoniadi looked at Mercury and what he saw didn't look the way he imagined it should, he thought clouds were interfering with his view - clouds on Mercury, I mean. A dark spot was hidden by hazes, or a bright spot was a thick cloud.

So this map can't be used as you suggest. When the rotation became known (from radar studies) a new map was compiled and used to redistribute placenames around the planet for the IAU. Rotational effects do make our views selective, so there is some relationship between Antoniadi's map and the later IAU map. But your question really should be applied to the IAU map.

Incidentally, the original names of USGS map sheets are taken from the old albedo nomenclature. Caloris is in Liguria, if you need to know!

Phil
SpaceListener
A quick questions.

I doubt that Messenger will not take zoomed pictures like MRO? I am not able to get the value of image resolution (m/pixel) of narrow and wide angle imagers of Mercury Dual Imaging System.

I am interested if MDIS will be able to take an even more detailed pictures of landforms and surface features than the recently posted ones.

Is the Mercurian landform regolith alike to Moon since Solar energetic particles bombard its surface even stronger and more than on the Moon? This would lead that the Mercurian surface would very dusty like Moon or Mars?
djellison
This single image was picked to be downlinked as it was the highest resolution image image that included the whole planet. It's about 3km/pixel

Now - MDIS will not reach HiRISE resolutions. But the highest resolution images from this flyby will be about 120m/pixel - so about 25 times better than this first returned image.

http://messenger.jhuapl.edu/encounters/ind...&timestep=7

Doug
JJR2
QUOTE (gndonald @ Jan 16 2008, 02:53 AM) *
That is indeed, and it's replacing my current wallpaper (an Apollo montage), it'll be interesting to see just how many people mistake this for the Moon (and believe me it will happen).

I don't know if I'm quite ready to replace my Spitzer IR montage of the center of our galaxy just yet.

So, will we have to wait until 2011 for the "good stuff"?
elakdawalla
Heavens no. The best stuff from this flyby will be that narrow-angle camera mosaic of the equatorial region that Doug mentioned -- at 100-200 m/pixel, it will be higher-resolution than any images MESSENGER will be able to get of that same area once it's in orbit. MESSENGER's orbit is elliptical with periapsis near the north pole; it'll get slightly higher resolution views of high northern latitudes but the orbit gets farther out at equatorial and southern latitudes, so this flyby mosaic will be as good as it gets. And I'm really looking forward to the departure mosaics, particularly the one taken about an hour after close approach, which should produce an image of Mercury that is superficially similar to the already-released wide-angle shot, except it'll have about 10 times better resolution, and be between 9,000 and 10,000 pixels high. There will be color data taken just before it, so they'll be able to colorize the view. It should be awesome.

--Emily
tedstryk
The image they have now is probably from the set from which they will derive the color data. As for Antoniadi, what would be interesting is to find some of his old drawings from which he compiled the map and see if anything is recognizable.
Phil Stooke
A good project for you, Ted!

Phil
Bjorn Jonsson
A fairly high resolution image is now available:

http://messenger.jhuapl.edu/gallery/scienc...mp;image_id=118
elakdawalla
QUOTE (tedstryk @ Jan 16 2008, 10:05 AM) *
The image they have now is probably from the set from which they will derive the color data.

Actually, the already-released image was taken after the second NAC departure mosaic. There is a WAC departure mosaic with twice the resolution of the already-released image that will be taken just before the first NAC departure mosaic. Though I suppose it'd be easier, initially, to apply color from the lower-resolution, single-frame WAC observation than to apply color from a 3x3 mosaic onto a different mosaic.

--Emily
Stu
QUOTE (Bjorn Jonsson @ Jan 16 2008, 06:23 PM) *
A fairly high resolution image is now available:

http://messenger.jhuapl.edu/gallery/scienc...mp;image_id=118


ohmy.gif ohmy.gif

I think we're all going to need new swear jars if that's just a "fairly high resolution" image...
volcanopele
Nice image of Vivaldi!
dvandorn
QUOTE (Bjorn Jonsson @ Jan 16 2008, 12:23 PM) *
A fairly high resolution image is now available:

http://messenger.jhuapl.edu/gallery/scienc...mp;image_id=118

Broken link:

FATAL ERROR: cannot connect to mySQL server
host: sd-mysql:3307
user: regieal1

-the other Doug
akuo
The whole Messenger site seems to be broken. If anyone grabbed the hi-res pic, posting it here would be very much appreciated!
Jyril
Direct link.
jamescanvin
QUOTE (dvandorn @ Jan 16 2008, 06:41 PM) *
Broken link:


Try This. smile.gif

http://messenger.jhuapl.edu/gallery/scienc...0108821483M.png
dvandorn
Thanks, guys!

Now, where did that swear jar go...?

WOW!

Yep, that's Mercury, all right. The fold-over ridges and the central rings in the larger craters give it away. Kewl -- first close-ups of Mercury in 30 years!!!

-the other Doug
volcanopele
Interesting new image. Obviously, the most interesting feature is the multi-ring basin, Vivaldi. Many of the smaller impact craters surrounding this feature appear to be secondaries from that impact. You can pick out a few secondary chains that point to Vivaldi. Vivaldi appears to have impacted into a larger basin (or a couple of superimposed impact craters) that is visible to its southwest. Strangely, that basin isn't covered in Vivaldi's secondaries, which may mean that: a) Vivaldi and these smaller basins to its southwest occurred at the same time (plausible if this impactor had satellites); or B) the smaller basins are actually younger (though the superimposed crater density in the heavily crater terrain to the west and southwest of Vivaldi and its siblings is similar to that found in the siblings).

The terrain on the left side of the image appears to be fairly smooth, volcanic plains. You can even make out a few, degraded wrinkle ridges.
Stu
Sharpened up a bit it could be a featured image from the (brilliant) Lunar Picture Of the Day website...

Click to view attachment
Tom Tamlyn
QUOTE (dvandorn @ Jan 16 2008, 08:23 AM) *
OK -- 30 kilobits per second, I can see. At 30 kilobytes per hour, you would be getting about 210 kilobytes over seven hours, and even the jpeg'ed images we've already seen are larger than that. Each.

Unless there is some kind of uber-compression going on here of which I'm not aware, I would think it would be hard to fit 1,200 images into a file only 210 KB large.


Now I'm curious. How big are these images? And how many 7 hour sessions with a 70 meter dish will it take to download 1,200 of them?

TTT
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