Help - Search - Members - Calendar
Full Version: Mercury Flyby 1
Unmanned Spaceflight.com > Inner Solar System and the Sun > Mercury > Messenger
Pages: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12
elakdawalla
My first, fleeting impression of the smallest craters in this image was that somehow they'd made a terrible mistake and given us an old Mariner 10 image, complete with reseaux.

--Emily
ugordan
The effect is probably due to a combination of a oblique viewing angle and illumination - we're looking precisely at the shadowed crater walls here.
MarsIsImportant
QUOTE (dvandorn @ Jan 18 2008, 05:21 PM) *
My most overwhelming impression of the surface, especially on the inbound full-crescent views, is that Mercury's LHB-carved surface has been almost completely covered with lava flows. The population of completely expressed large craters / small basins is relatively small, especially as compared to our Moon. The population of these large craters / small basins which are expressed only as circular deformations of a relatively smooth covering layer is very similar to the population of non-covered craters in the lunar highlands.

Conclusion? Mercury was resurfaced (if imperfectly) *after* the LHB, and now only exhibits "uncovered" craters from the three and a half billion years since its end.

-the other Doug


The more I look at these new images, the more I agree.

But these latest images reveal an even more complex history on Mercury. You can see the ancient lava flows that presumably reworked the LHB surface. On top of that we can see another ancient heavy impact episode in which the impactors were generally smallish in diameter. Then you have another more recent episode with larger impactors in a mid-range size. We need surface composition maps to make any real sense of all this. I have a feeling that things are not exactly what they may seem at first.

Mercury is very different from both Mars and our Moon. It seems to be telling us a completely new story. I would love to get confirmation of the ages for some of these features. We need an advanced MerSL rover (maybe AMerSL--Advanced Mercury Science Lab) that can determine ages of various rock. With the extreme Delta V associated with getting to Mercury, there is little chance of a return sample mission.

I understand that such a mission would likely be FAR into the future; but we need one.
Juramike
QUOTE (Paolo @ Jan 20 2008, 10:43 AM) *


This newly released image is a zoom of the area discussed in post above.

Here is a graphic showing how this image relates to the previously released larger image:

Click to view attachment

And as Emily and Phil Stooke pointed out, the central portion is not a collapsed area, rather it is between two wrinkle ridges. As detailed in the image release:

"These lobate scarps were formed during a period when Mercury’s crust was contracting as the planet cooled. In contrast, the branch of the Y to the left ends at the crater rim and is restricted to the floor of the crater. Both it and the lighter-colored ridge that extends downward from it resemble “wrinkle ridges” that are common on the large volcanic plains, or "maria," on the Moon. "

With the regional image you can see how the wrinkle ridges extend over a large area.

-Mike
Astro0
Here's an update on the images released so far overlaid on the newly imaged face of Mercury.
I had to fudge a bit on the central area due to the angle of the original image, but you get the idea.
Click to view attachment

Astro0

PS: I especially like the 50km scale bar that now appears on the image on the lower left.
Phil Stooke
Curiouser and curiouser...

Stu, in post 346 (above) noted a crater with a rimless pit in it. It was also shown in my reprojection of that same image. Then the science team released an image showing another one, "telephone-shaped". And in the lower right corner of that same release was yet another rimless pit, which they didn't mention.

Now we have a new image of the south pole. Look in its upper right corner and you will find another of these features. (I'm away from my Photoshop and can't illustrate it).

So rimless pits in crater interiors may be common on Mercury. Marsisimportant was discussing volcanic features - I disagreed about his example, but I could very well believe that these odd features are volcanic in origin.

Phil
jamescanvin
Another one trickles out...

Looking Toward the South Pole of Mercury
Juramike
Here is a graphic showing the feature that Phil was referring to:

Click to view attachment

(Released image found here: http://messenger.jhuapl.edu/gallery/scienc...mp;image_id=131)

I'm going to retract my retraction. The depressed area in the post discussed far above (Post 342, this thread) sits in the center of a larger, older crater. Could be this is an older version of a rimless pit that was covered up? (Or covered then slumped?). Here is a graphic showing my putative collapsed area inside the larger, older crater:

Click to view attachment

-Mike
Bill Harris
And what we may be seeing might be partially tectonic and erosional phenomena. Remember, the maximum surface temperature is about halfway to the melting point of the rock (equivalent to our lithosphere some 30 miles deep), with an overall max-min temperature range of some 1100 degrees and the surface is also blasted with strong solar wind, which can disrupt the crystal structure of minerals.

Another alien world...

--Bill
jaywee
QUOTE (jamescanvin @ Jan 21 2008, 04:56 PM) *
Another one trickles out...

Looking Toward the South Pole of Mercury


Any idea what might be the very bright feature in the SW corner?
jamescanvin
QUOTE (jaywee @ Jan 21 2008, 05:25 PM) *
Any idea what might be the very bright feature in the SW corner?


I wondered how long it would be before someone mentioned that. rolleyes.gif

I guess it's one of the famous "Wrinkle Ridges" heading over the terminator
SigurRosFan
Interesting story ...

----------
Messenger team member Jeffrey Gillis-Davis of the Hawaii Institute of Geophysics and Planetology has drawn attention to the sharp cliffs and escarpments visible on the close-up images.

These features indicate that the whole planet shrank as it cooled, he told New Scientist.
----------

- Has Messenger revealed lava flows on Mercury?
tedstryk
Click to view attachment

It caught me off guard to see the albedo features in Messenger images. It is probably from being used to the old Mariner mosaics. Even in this distant south polar shot, the planet looks remarkably similar to the Messenger outbound global view.
As old as Voyager
Interesting interview with Scott Murchie on MESSENGER's first Mercury flyby:

http://www.physorg.com/news120143527.html
nprev
QUOTE (SigurRosFan @ Jan 21 2008, 10:31 AM) *
These features indicate that the whole planet shrank as it cooled, he told New Scientist.


Not to denigrate the story, but the 'shrinkage' hypothesis has been around since Mariner 10 following discovery of the scarps. See Murray & Burgess, Flight to Mercury (1977, Columbia University Press). This book is an excellent context primer for Messenger, if you can find it.
tedstryk
I don't think Murchie ever claims that Messenger discovered the scarps. He just explains them and talks about seeing them in the Messenger data and points to the fact that Messenger will allow us to test and refine our ideas about them using Messenger data.
gcecil
I've just returned from a great visit to the geology "back room" at APL in Laurel. Can't comment on the many wonderful conversations and plenty of lively discussion at the 2pm science update conference that I presented briefly at. But I will say that the NAC mosaic #2 of the N hemisphere will absolutely blow your socks off when it is revealed on the 30th! It is nowhere near fully resolved on the 4x4 ft working image posted in front of the toiling geologists. Wait until it is colorized from the WAC mosaic and printed at 3x the area/resolution. Astonishing, HUGE crater ejecta blankets on non-Mariner imaged features that I saw as bright splotches barely resolved from the ground, rupes, overlapping lava flows, etc. You'll see for yourself in less than 10 days. There was much discussion of fascinating features on the approach (Mariner 10) side, which reveal "a completely different planet" in the words of one geologist who presented. Plenty of surprises with Caloris. All instruments got data, teams continue working through calibrations and improved trajectory analysis to pin down viewing geometry for multicolor registration. A new world revealed in so many facets. An astonishing achievement by Prof. Solomon and his great team.
nprev
QUOTE (gcecil @ Jan 21 2008, 05:21 PM) *
. Wait until it is colorized from the WAC mosaic and printed at 3x the area/resolution. Astonishing, HUGE crater ejecta blankets on non-Mariner imaged features that I saw as bright splotches barely resolved from the ground, rupes, overlapping lava flows, etc. You'll see for yourself in less than 10 days. There was much discussion of fascinating features on the approach (Mariner 10) side, which reveal "a completely different planet" in the words of one geologist who presented. Plenty of surprises with Caloris. All instruments got data, teams continue working through calibrations and improved trajectory analysis to pin down viewing geometry for multicolor registration. A new world revealed in so many facets.


To say that I'm salivating would be an understatement; thank you, gcecil!!!!!

I think that we have a genuine heuristic for planetary exploration now: for each improvement in resolution and/or instrumentation, we will find more features that will overturn, rather then confirm, our expectations, and raise more questions then we originally thought we would have to answer. (A chaotic paradigm to be sure, but apparently true for reality.)

What a time to be alive. smile.gif
tedstryk
While we are waiting, here is my incoming mosaic. I mixed minus uv, blue and clear, and blue and uv to make a very approximate OGV combination.

Click to view attachment
edstrick
"...While we are waiting, here is my incoming mosaic..."

Thanks !!!
That's a view I've been waiting for for 33+ years

The Mariner 10 cam was pretty good, but it's decalibration left a lot to be desired, partly because of comp limitations at the time.

The thing that really was sucky was the color filter set. I never saw a really clear explanation of what they picked and why it was so bad on it's primary target. Mariner 9 at Mars had an excellent set of filters: Red, Green, Blue and Violet for the color set, similarly shaped medium-wide spectral bands with little overlap should have given a good first look at Martian multispectral patterns. But the camera was uncalibratable due to residual image (damn near) and then the filter wheel stuck on an orange-polarizing passband and THEN the dust storm cleared. Aaaarughhhh.
4th rock from the sun
Nice mosaic! I do like the colors, at least they are consistent, although I'm not a fan myself of Voyager like OGV ou OBV color compositions. Of couse, and having worked with the M10 data, any atempt to get "real color" out of that filter set is very difficult. I really like the overall orange-brown color, it looks real to me.
ugordan
Color ahoy!!!
elakdawalla
Woo hoo!

What do you think of that "orange-brown color," 4th rock? smile.gif

--Emily
Juramike
QUOTE (ugordan @ Jan 22 2008, 12:23 PM) *


I like the little "blue splat" at lower center of the released image:

Click to view attachment


-Mike
ugordan
QUOTE (elakdawalla @ Jan 22 2008, 06:35 PM) *
What do you think of that "orange-brown color," 4th rock? smile.gif

It looks a bit stretched to me personally. biggrin.gif

Mike, I think we'll find all the fresh(er) craters will have blue ejecta blankets in this filter combo, this probably signifies less space weathering and... well, fresher materials. The same thing we see on icy moons, only different compositions.
I wonder how much of the blue hue is due to compositional differences (less meteoric dust in the regolith) and how much is due to crystallinity of materials? Would crystalline materials appear any bluer, anyway?
tedstryk
I am pleasantly surprised to see that the color, which does seem a bit stretched, matches my crescent OGV view fairly well (the one I posted last night), but my color is much more subdued.
JRehling
[...]
JRehling
[...]
ugordan
I actually think they brightened the violet frame to match the brightness of the IR frames, for the sake of pleasing appearance. I'm skeptical the blue splat actually is brighter in violet than in IR, only brighter than the rest of the planet. It'd be cool to be wrong, though, that would mean Mercury's much more colorful than our Moon.

If you look at the first MESSENGER spectrum of Mercury, you can see the sample of the "normal" surface is much dimmer in the violet portion than in the IR. The "true" color might actually turn out to be much redder/more brownish than this and the fresh ejecta might turn out to be more gray. That's my hunch at least.

If only they put some wavelength marks on that spectrum, I could run it through some CIE XYZ code and see what color that would approximate to the human eye.

Taking that spectrum and taking a rough ratio between R/B wavelengths (I get blue slightly over 80% as bright as red) and applying that to the neutral regions of Mercury (approximating the 700 nm filter brightness as red for a first iteration and taking the 430 nm violet as blue, with a synthetic green from the two) gives roughly something like this:


Ugly? Wait, that's not all. Invariably, almost all spacecraft images are displayed non-gamma corrected because that increases the contrast and color saturation. If we apply the sRGB correct gamma of 2.2 to essentially linear spacecraft data, this is the end result:


That winds up looking similar to the false color composite, only with less pronounced blue hues. It's also similar to Ted's earlier composite.
As a comparison, non-gamma-corrected imagery is usually responsible for a very brown-looking Moon seen by many spacecraft.
4th rock from the sun
QUOTE (elakdawalla @ Jan 22 2008, 05:35 PM) *
What do you think of that "orange-brown color," 4th rock? smile.gif


I like it :-) The most important thing is that the brown hue (moon like but more saturated) seems consistent in M10 images, earthbased views and this Messenger image, even considering that each image was derived from very different filters. That's not completely surprising, as the planet's spectrum is close to a straight line. So you can get almost any 3 evenly spaced wavelengths and get the same global tone.
tedstryk
QUOTE (4th rock from the sun @ Jan 22 2008, 08:43 PM) *
I like it :-)


Regarding your OGV or UV comments....Of course, with vidicon's red-blindness, it is often our best option. It has always bothered me more than a red/near IR shift because it tends to give fewer new interesting color feature in exchange for not being as "human." However, with some worlds, it is more bothersome that others. For example, Ganymede doesn't look too much different in properly done Voyager and Galileo color. However, Io and Europa look quite different. Mercury, with its rather flat spectral curve, appears to be more like Ganymede in its response to color shifting.
Bill Harris
It has been decades since I've observed Mercury through a telescope, but I'll alwasy remember it as having a warm hue: the "orange-brown" color noted upstream. Of course there is always the personal equation on the perception of "true (or actual?) color", but there is some validity to the perceived color of Mercury.

One classic example of color mis-perception is found on telescopic views of Mars. The darker albedo markings (AKA "Mare") have long been perceived to have a blue-green hue, caused by the contrast with the orange color of the adjacent lighter areas.

--Bill
DrShank
Ive taken the released color image and applied some simple saturation to it. some of the color differences begin to come out, including the blue crater and some orange patches. looks like there could be some interesting geologic patterns!

paul
Click to view attachment
4th rock from the sun
QUOTE (tedstryk @ Jan 22 2008, 09:29 PM) *
Regarding your OGV or UV comments..... However, Io and Europa look quite different. ....


I agree. The only solution for working with wavelenght outside the visible (or borderline visible like violet) is some sort of colorspace convertion. This way, a OGV composite can have some "red". That "red" will come from a correct display of the violet filter into RGB space. Simply put, Violet in RGB corresponds to both the Blue and Red channel (of course mainly to the Blue, but witha significative presence in the Red).
ugordan
QUOTE (4th rock from the sun @ Jan 23 2008, 12:59 PM) *
Simply put, Violet in RGB corresponds to both the Blue and Red channel (of course mainly to the Blue, but witha significative presence in the Red).

Of course, even then you can have problems with freaky-looking spectra for example for features that exist in the blue end of the spectrum, but are virtually nonexistent in violet. Not very likely in nature, but still. You'd lose that information in such expanded filter sets, even with colorspace conversion.

It's frustrating how inexact a science "natural color" really is. The fact Mercury's spectra looks very flat eases things a bit here.
algorimancer
QUOTE (DrShank @ Jan 22 2008, 11:29 PM) *
Ive taken the released color image and applied some simple saturation to it....

I like that a lot. I wish I could do the same thing with my eyes and see the world like this smile.gif
J.J.
I second Harris...many good amateur observers of Mercury have commented on its distinct coppery hue.
jamescanvin
Another nice new image taken near the terminator on the approch is in the 'pics' folder. It doesn't seem to be on the main MESSENGER page yet.

http://messenger.jhuapl.edu/gallery/scienc...0108821375M.png
elakdawalla
I'd like to see the Phil-o-vision version of this one--I think I see another large, nearly completely smoothed-out basin in the middle of this image, just like the one in the first near-limb approach shot they released.

--Emily
JRehling
[...]
Phil Stooke
Click to view attachment

Oh, very well, Ms. L., here you go. It's SE of Beethoven, and there's a hint of a buried basin in it.



Phil
ngunn
I don't think there's much doubt that the big thing in the middle is another almost-erased impact feature. I see also above it in that image, and about half the size, a clearly defined circular (or elliptical) area that appears to be a raised platform. Could an ancient impact feature end up like that in some circumstances? Or is that circle just a chance effect/optical illusion?
Oersted
QUOTE (algorimancer @ Jan 23 2008, 02:58 PM) *
I like that a lot. I wish I could do the same thing with my eyes and see the world like this smile.gif


It's called LSD smile.gif
dvandorn
QUOTE (ngunn @ Jan 23 2008, 04:00 PM) *
I don't think there's much doubt that the big thing in the middle is another almost-erased impact feature. I see also above it in that image, and about half the size, a clearly defined circular (or elliptical) area that appears to be a raised platform. Could an ancient impact feature end up like that in some circumstances? Or is that circle just a chance effect/optical illusion?

As I've noted, there are thousands and thousands of buried craters evident in the intercrater plains. Looks like a heavily cratered surface, a la the lunar highlands, has been covered over with lava.

-the other Doug
Doc
In the image EN0108821375M(post #439) the big crater(wats its name?) in the upper right corner is surrounded by small elongated craters radiating from it. Did the ejecta from the impact form these elongated craters?
edstrick
The question ever since Mariner 10 has been the nature of the intercrater plains, and possible differences between them and circum Caloris plains and the cracked intra-Caloris plains.

They look generically like old intercrater highland plains in areas on the moon like Mare Australe with all the flooded craters. Areas that on the moon are clearly lava flooded, though sometimes covered with a disguising mantle of ejecta. But they are more or less rather severely cratered, spattered with a lot of secondaries and small primaries, and have lost through small feature blurring and battering any (or at least most) of the more uniquely distinguishing features of lava flooded plains.

Some of them are so reasonably well defined and far enough from Caloris that it's very unlikely they're Caloris melt-sheets. I think limited crater counting indicates they're younger than Caloris impact features, but there's not a lot of good, high resolution, near but not too near terminator data that's not near Caloris to get good data on it from the Mariner flyby. Color data, processed by Robinson, is strongly suggestive of lava flows in some areas, with some discrete color boundaries that do not appear crater or ejecta related. But it's just not unambiguous. Certainly, most areas of cratered plains are not obviously different in color or albedo from much of the more cratered surface.

The far better flyby color data and the doubling of the surface area that's been imaged <or a bit more than doubling> will permit better photo-geologic studies, color composition or at least color boundary mapping than before, giving a real advancement in digging into this problem. Orbital gamma/xray data may be needed to really sort things out.

Regarding Mercury's color and the Moon's color... Mercury's spectrum is very very similar to weathered lunar highland (not fresh impact) terrain. Very weak spectral features on a strong redward slope from UV through near IR. The moon tends to totally dominate things when we're looking at it, and the eye shifts it's color to white, but it's really brownish gray to brownish black. I expect the fresheshest, least weathered crater ejecta to be near white, other than any distinct spectral features of iron bearing <mostly> minerals in the ejecta.
elakdawalla
Can anybody download today's release image? I'm having trouble getting the enlarged version.

They seem to have closed the loophole that let us peek into the pics folder, darn it rolleyes.gif

--Emily
JRehling
[...]
Phil Stooke
Me too.

Doc (post #446): the answer is Yes!

Phil
This is a "lo-fi" version of our main content. To view the full version with more information, formatting and images, please click here.
Invision Power Board © 2001-2020 Invision Power Services, Inc.