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J. W. Daniels, MSc

One of Dr. Neish's new "friends."

Mercury’s “Group of Seven.”

The “Group of Seven” was the name given to a number of Canadian artists who painted landscapes in the same style at around the same time; the original group was:  Franklin Carmichael, Lawren Harris, A. Y. Jackson, Frank Johnston, Arthur Lismer, J. E. H. MacDonald, and Frederick Varley.  Tom Thomson was noted as being the “founding father” of this artistic movement that was predominant almost 100 years ago now.

Tom Thomson’s ‘the Jack Pine’ (1916) ~ from Wikipedia

A little Canada hype, since it’s turning 150 this year….

My first GIS-processed crater results are well on their way to being completely analyzed.  The best MDIS and MLA data have been attained for seven Mercurian craters so far.  These craters are:  Abedin, Hokusai, Stieglitz, and four unnamed craters.  Mercury’s “Group of Seven,” if you will.

unnamed crater 4
An example:  One of the unnamed craters…, currently possesses the largest melt deposit (wrt crater size) of all 36 crater candidates.  Melts highlighted in lavender, crater rim drawn in blue, the crater’s “floor” is coloured green, and the red contour line is to highlight the crater’s rim crest low.

All seven craters reside at a latitude greater than 45*N; Hokusai and Abedin are neighbours, and the four unnamed craters are also neighbours to each other; Stieglitz is the closest of the craters to the North Pole, and is located nearest to Hokusai; most of these craters can be found within 90* (E or W) of Mercury’s “Prime Meridian.”

The other craters in my list are also being prepared; unfortunately, virtually all of them have very poor MLA data and so it looks like the next best thing for me is to use the “Mercury MESSENGER Global Colorized Shaded Relief” map with a resolution of 64 pixels per degree (ppd).  For comparison, the MLA imagery used for the seven craters above is at ~170 ppd while the MDIS mosaic imagery is at 256 ppd.

More of that in later updates, though….

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Fun-Fun-Fun!

GIS project files are currently being made for the original 13 named craters for which MDIS + MLA snippets have been obtained.  The MDIS crater files were easy enough to obtain, but the corresponding MLA was trickier — north + south lat. for MDIS + MLA are the same as well as the east long., but the west long. values for MLA go from 180 to 360 instead of -180 to 0 as with the MDIS.

Once I realized that, I was able to crop out crater files from the MLA that would have the same dimensions as the corresponding MDIS files as well as be centered over the same crater (unlike in a previous post featuring John Lennon where the MLA image I thought was of Hokusai actually is not!).  Then, it was a matter of making sure QGIS would actually render each MDIS + MLA image on top of each other — easier said than done!

Interestingly, I expected the two maps to be misaligned by 180* (or something similar).  Instead, the maps’ boundaries aligned perfectly but the craters themselves weren’t aligned between the MDIS and MLA data-sets.

QGIS screenshot (MDIS + MLA full)
MLA map overlain on the MDIS map in QGIS; the boundaries match but the craters therein do not.

QGIS screenshot (misalignment confirmed...)

Thanks to some ISIS help from Dr. Neish, the use of “maptemplate &” in tandem with “map2map &” allowed my cropped-out craters to be properly rendered in QGIS under a sinusoidal projection centered upon the crater itself.

Abedin_dataMatches

Abedin crater file:  images match, now to get rid of those annoying polygons and to begin the actual analysis process.

Now the fun stuff can begin!  Contouring the MLA file for each crater will help me determine the most likely location of each crater’s rim crest low, and from there I’ll be able to correlate to where the melt deposits are located and thus compose, hopefully, a more accurate plot of Mercury’s complex craters for comparison with the Neish et al. (2017) figure concerning the Moon and Venus.

All in due time….

I Haz Resultz!!

After a week or so of cataloging all the unnamed craters alongside the named craters I already cataloged, as well as re-inducting several more craters I previously discarded and even obtaining a number of brand new candidates, I — at last! — have some cool new results!  **and another .ppt file of craters & results to show for it….

^_^

My Mercurian crater count now is the highest it’s ever been, at 36 (19 named & 17 unnamed).  The smallest crater is now an unnamed crater @ 19.93 x 63.58 with a diameter of only 16 km (the largest is still Abedin @ 116 km wide).  I even have a melt flow crater now (see below)!

Area west of 19.6 x 81.29, note the darker material (via MODE).

As for the results:  “Figure 3” of Neish et al. (2017) shows how craters whose exterior melt deposits tend to coincide with their rim crest low dominate the Lunar complex craters studied, while on Venus the majority of the craters studied had their melt deposits found around 90* or greater from the low.  As for Mercury, analyzing the 36 craters using JMARS has yielded the preliminary result of possessing a large number of craters in the “coincide” area (like the Moon) but also a large number in the “>90*” category (like Venus).  This implies that Mercury lies intermediate to the Moon & Venus, when it comes to impact melt emplacement.

As hypothesized!  Yay!

So… what does this mean?  Well, my initial hypothesis here is that there could be two factors at play here:  First, although Mercury has higher topography (averaged over its entire surface) than Venus it may actually have slightly lower topography than the Moon; thus, unless the Mercurian crater in question is found in a high-topography area a crater’s melt will tend to emplace more like it does on Venus — that said, there is still high topography, hence the large “coincide” value.  Second, because complex craters on Mercury tend to be deeper than those on Venus yet shallower than those on the Moon it could be a matter, in some cases, of the structure of the crater itself; deeper craters on Mercury (w.r.t. crater size) may deposit melt more similarly to craters on the Moon, while shallower craters may deposit more like on Venus — where impactor direction is more important (something I’ll have to check, eventually, for Mercury by looking at the ejecta patterns about rayed craters…).

Analysis of my Mercurian craters in JMARS is a first step, to see what I’d find.  Now, the real analysis begins with downloading MDIS + MLA files for each crater and compiling them all using ArcMap.  That’ll keep me busy for a couple weeks, I think!

 

Try Everything!

The CPSX Field School experience has just ended, and so now the Grad-school summer vacation has officially begun!  Which means I can start making GIS projects for my Mercurian craters of interest….

                                               *~*Field School!!*~*

Meteor Crater — up close & awesome!!
Upheaval Dome:  impact crater, salt diapir, or a bit of both?

To say this CPSX course was/is one-of-a-kind is practically an understatement.  Every day feels like it goes by so quickly, yet when one wakes up the next day it feels as if the day before happened so long ago!  So much generally happens each day that even when you want to return home to civilization you still hope the field school could go on for longer.  Never experienced anything like it!  That’s not even getting into the myriad of stops….

Being that I’m currently studying impact craters on other worlds, it was only natural that I pay special attention to the confirmed+unconfirmed craters looked at during the trip:  Meteor Crater is a confirmed simple crater ~1.2 km in diameter, created mere thousands of years ago, complete with ejecta blanket and overturned strata on the south end of the rim.  As for Upheaval Dome, a ~5 km wide structure of uncertain origin, because a kilometer of strata has been removed via erosion what is seen now is only the very bottom-most “roots” of whatever it was that formed this structure — there are synclinal structures, faulting (including a graben or two), steeply dipping strata, and the presence of the “Paradox Formation” present at/near the central “uplift.”

Comparing Upheaval Dome to the Onion Creek salt diapir, once again the Paradox Formation resides at the center of it all; Onion Creek strata are also steeply dipping leading up to the Paradox, but there is intense folding present in the Paradox itself and faulting appears quite rare here.  Gypsum (& sometimes halides) was also found in situ in some of the Paradox units.

Other highlights include the hematite concretions at the Petrified Dunes, the eolian cross-stratification at the Grand Canyon, and the many interesting-looking cinder cones & other volcanoes (like the maar at Rattlesnake Peak) at the San Francisco Peaks area.

Because I wasn’t the only one who partook in this adventure, feel free to check out some of the other trip-goers for their own stories (assuming they post on it sometime between now & tomorrow…):

>>Elise.

>>Gavin.

>>Josh.

For everything else, there’s Twitter!

#PS9605

And now I shall return to my Mercurian craters….

 

An upcoming hiatus, + another small update.

As the Winter 2017 school year wraps up for me, I am soon coming up on many months of “free time” where I can really spend time on my Masters thesis — instead of any chance I can get for myself.

But, that’s still a month or so away for me….  As soon as Winter 2017 ends, CPSX field school 2017 begins; then, when I return at the middle of May, I have an annual committee meeting to tackle.  Fun-fun-fun!

Blog-wise, this means that I won’t be able to post for around two weeks.

That said, here’s a small update before I disappear to Arizona:

>All named craters have MDIS (Mercury Dual Imaging System) + MLA (Mercury Laser Altimetry) files associated to them — 13 craters in all.  There are still 13 or so nameless craters that need to be done.

Screen Shot Hokusai_MDIS
Hokusai (global MDIS mosaic — 166 m/pixel resolution)
Screen Shot Hokusai_MLA
Hokusai (MLA dataset — much lower resolution!)

>I’ve started gathering all the MDIS-NAC (the MDIS Narrow-Angle Camera) image files of the named craters — for use later on….

>I’m hoping to convert the files for Abedin, Hokusai, and Stieglitz to “polar-stereographic” sometime this week.  I also would like to try viewing at least some of the MDIS + MLA images in ArcMap before the Field School.

>If I can, I’d like to download the MDIS + MLA for the nameless craters before I go as well….

I have also been working on my Annual Committee Meeting report, and am very nearly finished.  The next thing to do now is to draft-up a presentation (more fun).

 

Post-Space Day: a slight update.

Current crater count = 14 named craters, 13 unnamed craters (27 total; removed a couple craters that weren’t viable for the study, but (re-)added a few more new + previously identified craters).

Smallest crater = Ailey @ 23 km in diameter.

Largest crater = Abedin crater @ 116 km in diameter.

Three cases:

1 = one melt deposit (15 craters); usually the smaller craters.

2 = two or more melt deposits (8 craters); usually the larger craters.

3 = melt inside adjacent crater (4 craters); no size preference.

In other news, I’m still not completely out of the school-work woods just yet — and I’ll be busy with school until the middle of May (June through August looks pretty free, though!); would still like to figure out how to find unnamed craters in the MDIS database, & get some craters mapped by May; also, GUI doesn’t like, so far, the MLA datasets I downloaded (I think it’s to do with the .lbl files but the GUI won’t even select them)….

That’s about it, at the present moment.  Have a great Easter, all!

 

What I know so far…: Mercurian craters.

With “Space Day” coming up next week @UWO, I figured it’d be a good idea to jot down what I’ve noted about fresh crater impact melts on Mercury in preparation for that fateful day.

As if I didn’t already have enough to do…!

Here’s what I’ve got so far:

>>15 named craters + 9 unnamed craters = 24 craters in total.  Up to 6 other, less-promising candidates….

>>Smallest crater w/ exterior melt = Ailey crater with a diameter of 23 km; Ailey appears to be on the transition from simple to complex crater form.

Ailey crater

>>6 craters, most of them >100 km in diameter, have more than 1 unique pooling of impact melt.  Most have 2, but a couple, like Hokusai, have 3 or more.

Tyagaraja crater

>>6 craters are found adjacent to older craters, and as such their collection of melt is almost exclusively found within that older crater.  For this group, for some reason the older crater tends to be located just to the north of the fresher crater.

Balanchine crater

>>For the remaining craters, the majority of the smaller complex craters, have only 1 collection of melt present.

Plath crater

To recap, here’s what Neish et al. (2016) & Neish et al. (2014) have found for Venus & the Moon, respectively:

>Venus — 19% coincide, 31% up to 45*, 17% up to 90*, and 33% >90*.

>Moon — 53% coincide, 27% up to 45*, 7% up to 90*, and 13% >90*.

 

That’s all I got at the moment!  The next step now is to locate the rim-crest low for each crater, and for that I’ll need to figure out the topography dataset….  I’ll also stress that my work so far is preliminary and I still have a fair number of things to do yet that hopefully will confirm these initial findings of mine.

The results look promising already, though.  More to come in due time!

[the images are screencaps from:  https://messenger-act.actgate.com/msgr_public_released/react_quickmap.html]

Pi(e) Day!

Did you know today is Pi Day?

Well, now you do!

Every year, on March (3) 14, at 3:14 pm.  How many digits of pi have you memorized?

Me:  3.14159 — thanks to Stargate, of all shows….

😀

Fresh impact melts – the best of the best (so far).

The following are the absolute finest Mercurial craters in possession of impact melt located just beyond their respective crater rims, listed from most to least optimal candidates:

1 = Hokusai (57.75, 16.71; 114 km).  Lots of quality images available, and lots of instances of impact melt residing just outside the crater rim; much of the melt is found along the west-to-south trace of Hokusai, but another large collection exists off the eastern rim as well as a small pooling off the northern rim.

2 = Abedin (61.73, -10.54; 116.25 km).  Virtually all the visible melt can be found off the western (from NW to SW) rim of the crater; once again, a fair number of high-resolution images are available for this crater.

3 = Apollodorus (30.57, 163.28; 41.5 km).  Besides having a fairly unique radial pattern associated with it, this crater also possesses a nice collection of melt located in a sizeable area south of the crater itself.

4 = Seuss (7.65, 33.16; 64 km).  The melts present at this crater aren’t exactly the best-looking, but are found in two very large collections located to the east and south of the crater itself.

5 = Degas (37.10, -127.37; 54 km).  The high-resolution images available for this crater were instrumental, more than most of the other craters I’ve looked at thus far, in determining where the melts were located; there are, in fact, two small collections located south and west of the crater itself.

6 = Kulthum (50.72, 93.56; 31 km).  There are three small collections of melt present, located NE, NW, and SW of the crater itself.  Once again, the high-resolution images were instrumental in determining more exact locations for these melts.

The following craters also contain excellent collections of external impact melts, but are located within a much older crater situated right beside the crater in question (usually just to the north of the fresh crater):

1 = Erte (27.41, -117.31; 242.5 km).  Largest crater in the list overall, at roughly twice the size of Hokusai; there are two large collections of melts, the larger of which are located to the north inside an even larger, older, crater while the smaller is located to the E/NE of Erte.

2 = Balanchine (38.46, 175.50; 38 km).  Melts are pooled within an old crater located between Balanchine and a middle-aged crater located to the NW.

3 = Ailey (45.58, 177.92; 23 km).  Smallest crater in the list, overall; one large pool of melt is located within the old crater located just north of Ailey.

4 = Kyosai (25.16, 4.90; 39 km).  Virtually all melt is located within an older crater located north of Kyosai.

That’s it!  For now, that is!  This list shall be expanded once I search the high-resolution images for all the unnamed craters I’ve identified as promising candidates (still figuring out how to make the site search an area by coordinates…) and I search Braden et al. (2013) for any Kuiperian craters I’ve missed.  I hope to have those results by next week, or so….

[crater data – lat, long; diameter – obtained via https://messenger-act.actgate.com/%5D

 

 

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