This is just the first of what will presumably be many new sets of names for features on Mercury produced by MESSENGER's imaging:



Beagle Rupes is the big curvy rupes near the western terminator on the outbound images. Pantheon Fossae is the "spider." Apollodorus is the crater that sits on the spider. Anyone care to try your hand at mapping out the locations of the other craters? They all seem to be on the outbound images, no surprise there.

Name Lat Lon Diameter
Raditladi 27.28 240.93 257
Xiao Zhao 10.64 236.21 23
Atget 25.65 193.93 100
Sander 42.59 205.6 50
Apollodorus 30.58 197.01 41
Sveinsdóttir -2.58 259.96 220
Eminescu 10.79 245.87 125
Cunningham 30.48 203.07 37
Kertész 27.44 214.06 33
Neruda -52.47 234.55 110

--Emily

I was wondering what Jason was talking about with Beagle Rupes. Although with the Mercury theme I expected Beatles Rupes.

Applldorus and Pantheon... nearby?

On a somewhat related note, I recently posted some Mercury mapping updates. These include more color imagery from Messenger and earlier radar data from Arecibo Observatory. Details are in the caption...

http://laps.noaa.gov/albers/sos/sos.html#MERCURY

Steve

Here ya go:

... and a nice new image on the Messenger site:

http://messenger.jhuapl.edu/gallery/scienc...0108828468M.jpg

Phil

Wow, I'll say!!! The central peak complex of that large terraced crater is just wild.

You're the man, Jason, thanks. I asked some APL folks if they had a map and no one seemed to have one to send, or know where the craters were! Maybe I'll send them your map.

--Emily

I believe that is Eminescu - nicely labeled on Jason's new map.

And some textbook secondary crater chains - beautiful!

I was wondering when somebody would mention those "secondary crater chains". I would like to see the textbook that depicts them. I find it hard to imagine that a series of ejecta blocks from the large crater would land one-after-another along those nearly-perfectly linear tracks, without at least an occasional block landing to one side or the other of the line. That's what I always see in the textbook chains on the Moon or elsewhere, but not here around "Eminescu".
These particular chains are impossibly continuous and co-linear to be formed by flying ejecta blocks. They are primarily radial to Eminescu but not always.
I am prepared to wager that they comprise series of sinkholes formed above linear fractures in an underlying basement rock. The fractures would have formed as a result of the Eminescu impact, but the sinkholes would represent a later modification, as deposited regolith sifted down into the cracks.
I don't think I have ever seen this kind of pattern on the Moon or other planets, and wonder if it is unique here. It implies a pretty remarkable substructure to the Mercurean crust. I can't believe no one else has commented on this. Emily?

Secondary cratering has been understood very well since the pioneering work by Gene Shoemaker in 1960 or so. The curtain of ejecta breaks up into debris strands, not always radial because some are produced by in flight breakup of rotating blocks. We see it around terrestrial explosion craters, lunar craters, Mars craters... and it is better expressed on Mercury because the higher gravity compared with the moon brings the debris down closer to the primary so there's less time for it to spread out and become irregular in appearance. Radial cracks are all but unheard of around impact craters.

Phil

Try 'Planetary Geology' by Guest/Butterworth/Murray/O'Donnell 1979 edition Page 22 with 4 photographs on the facing page - very informative.

Thanks for the pointer. I'll try to find it. Astonishing is all I can say, that a series of ballistic ejecta trajectories can produce craters like beads on a string.
Do the hydrocode models of big impacts produce patterns like this?
Incredible.

The crater chains are odd and cool, but I'm still obsssed with the albedo variations around the central peaks of Eminescu; is the crust much more chemically differentiated then previously thought?

Come to that, some of the crater chain patterns seem to perhaps imply activity post-formation. I wonder how deep beneath the outer crust Mercury's magma might really be? Might be very hard to tell; the place has been slammed continuously since its formation, but it's thick-skinned enough to retain prima facie very ancient impact features. Eminescu doesn't look all that old to me, though, especially in comparison to its presumably associated secondary impact chains.

Here are a couple of false color and natural-ish wide-angle color overlays over the higher resolution NAC image of Eminescu:

I've uploaded a segment extracted from my enhancement of the departure hemisphere color mosaic

Eminescu is a "middle aged" (sort of equivalent to Eartosthenian, on the Moon) crater with no particularly distinctive color/albedo patterns OTHER than the features surrounding the central peak-ring.

The rim and outer floor of Eminescu are a little "yellower" in the enhancement than most of the surrounding cratered terrain, though the "blue" splattering from the young ray crater to the east, outside the high-rez frame, is an overlay of somewhat masking color-noise. In the general vicinity, crater floor and intercrater plains seem "yellower" than the old crater rims and rugged intercrater terrain, giving the plains a generally neutral color in this enhancement. To the northeast, outside the high-rez frame, some crater walls and patches on the plains have an interesting "pink" color that may be distinctive material (this area was missed by the ejecta). A large degraded crater almost as big as Eminescu, just south of the bright "blue" ray crater, seems to have an unusual "dark blue" central peak, but higher resolution data would be needed to confirm this is real. Another crater in the south part of the enhanced low-rez image has a "pink" central peak, again needing confirmation as a real feature. Patches of a "dark purple-blue" terrain appear near the south east corner of the low-rez frame and extend further south out of the cropped frame and appear to be a patchy regional unit in the rugged highlands there.

But in general, beside near-terminator noise in the color data, the area around Eminescu (within about 3 crater diameters of it's rim) is largely devoid of prominant color variations.

This makes the intense "blue" color of the bright materal in and around the central peaks extremely distinctive. The data suggests also that the dark patches on the crater floor that immediately surround the bright "blue" areas are also strongly "blue" colored. Higher resolution would help confirm this.

A few other craters share this feature: most prominant is the impact basin with a prominent central ring that's to the north of Eminescu. Some of the impact craters within Caloris also have bright, bluish floors and maybe central peaks. One fairly young crater with weak ejecta rays well to the south of Eminescu also has a somewhat bright and blue central peak area. But overall, these features are very uncommon.

"Curiouser and curiouser" said Alice"

Here's a map with feature names, some of the new and some of the old ones, using a size threshold of 125km.

Click to view attachment

Full resolution: http://laps.noaa.gov/albers/sos/features/c...zero_center.png

Steve

Steve, besides adding feature names to your maps, I was wondering if you are working on any updates?

http://messenger.jhuapl.edu/gallery/scienc...mp;image_id=681

This is the most up to date map from MESSENGER. An updated version might be available in a week with the new PDS release.

Phil

CAP-Team, for Mercury a simple idea might be to use the latest MESSENGER map as a background and overlay the global images I've been using that have the lower phase angle? Working directly with 100s of high-resolution images would be a large task for me. Otherwise we can talk about ideas for updating particular maps. Sometimes I can benefit from a little coaching.

For the time being here are the features put on top of the MESSENGER map Phil linked to:

Click to view attachment

Higher Resolution (4K): http://laps.noaa.gov/albers/sos/features/c...zero_center.png

Steve

Some changes in Mercury nomenclature and new names. Previous Valles became Catenae and valleys (formed due to mechanical and thermal erosion of Mercury's surface by hot, low-viscosity, quickly-flowing lavas) have been named according to the theme of "abandoned cities (and towns and settlements) of antiquity" .
http://messenger.jhuapl.edu/gallery/scienc...p;image_id=1161
Regards,
Marc

Unfortuneatly clicking on the "next" for the third image results in an error.