My new blog is up and ready to go…. I just need to get it linked to “Neish & friends”!
*update* It’s been linked! https://planetneish.com/research.html
My new blog is up and ready to go…. I just need to get it linked to “Neish & friends”!
*update* It’s been linked! https://planetneish.com/research.html
I’ve completed all the statistical analyses possible through QGIS, so now all that’s left to do is calculate errors and display it all in some pretty little plots.
In the meantime, I’m going to follow some advice given by Dr. Tornabene and take a step back and decide which craters are worth keeping for good and which ones I should just discard for good. Below are my crater files, for looking through; theoretically, those worth keeping will be ones with an obvious melt deposit (or if equally-sized deposits are equidistant from the RCL), with an obvious RCL, with good and reliable MDIS and topography imagery, and with good and reliable stats produced from QGIS.
From my initial look-through of these craters, all things considered, it looks to me like my catalog will shrink from its maximum of 36 to a not-so-impressive 20-or-so craters that meet the considerations well enough to be kept for further use. Still more than the 15-or-so venusian craters looked at in the Neish et al. (2017) paper, though!
In preparation of conducting the mathematical analyses of my mercurian craters, I have completed the GIS files of all 36 of these craters including the two or three that have less-than-optimal data files associated with them. All MDIS, MLA/USGS, and contour, rim, floor, and melt files exist for each cataloged crater.
All was going well until I attempted to begin performing statistical analyses on these completed craters, and the statistical functions in QGIS wouldn’t spit out any numbers — or anything for that matter. As it turned out, the floor and rim shapefiles I created first time around had the incorrect coordinate system attached to them; so, while the shapefiles were drawn properly over their respective craters the coordinate system still believed those shapefiles were far elsewhere with respect to the craters they were supposed to be related to. Thus, I had to redraw the floor and rim shapefiles for nearly all 36 of the craters according to the correct coordinate system.
With the GIS files in the proper coordinate system, it appears from my initial run of stat-analyses on Abedin crater that numbers are being spat out as expected — the “qProf” and “zonal statistics” tools differ in the mean, std-dev, etc…, values they spit out, compared to each other, however. “qProf”, used for the rim, uses the raw elevation values, while “zonal statistics”, used for the floor, subtracts those elevation values from the radius of Mercury before it goes ahead and calculates the statistical values. Regardless, I can now statistically analyze the craters and from there prepare the final two plots that will take a similar form to Figures 4 and 7 of Neish et al. (2017).
Seven more craters have been plotted in my ongoing illustration of Mercurian crater melts vs RCL. Not only that, but I also managed to create a melts-vs-rays illustration using the five (yes…only five of my 36 craters show the asymmetric ray pattern that allows me to estimate direction of impact) rayed craters at my disposal.
Both Mercury plots follow the same trend, where the highest crater population lies “Within 45*”, more reflecting of the Moon; the second-highest population lies “>90*”, which is more in line with Venus.
It seems to me that topography is less important for Mercury than it is for the Moon, likely because of Mercury’s higher gravity; on the other hand, Mercury’s topography is comparable to the Moon’s and so becomes more important than for Venus. Because Mercury’s plot resembles more Venus’ than the Moon’s, it implies gravity is likely to be more important in melt emplacement for sufficiently large solid bodies than topography is likely to be; Perhaps, for solid bodies with lower gravity fields topography is indeed the more important factor. Perhaps, a transition exists at around 20-40% Earth’s gravity where topography and gravity become equally important (where one factor is transitioning in importance into the other).
I recently participated in a week-long field course at Sudbury, ON., taking a good look at one of Earth’s largest and oldest impact craters — the Sudbury Basin. As a result, I haven’t been able to work on my Thesis terribly much the past month or so. With one more important assignment due for that course a month from now, I suspect I will continue not being able to work as much as I’d like on my Thesis until December.
I have 31 craters I can start calculating ratios and what-not on, so I should still be able to complete virtually all that by Christmas. That’s my hope, anyway!
After nearly two decades of performing admirably, the Cassini spacecraft, nearly out of fuel, made one last service to Science by plunging into Saturn’s atmosphere sending its final stream of data back to Earth before burning up and thereby becoming a part of the planet it spent so many years getting to know.
Cassini officially burnt up yesterday, and for me such an act brought up this emotional scene from Haifuri — I imagine the great myriad of people who gave a fair share of their respective lives to the craft and its mission felt, more or less, like this:
The data Cassini collected over ~15 years about Saturn has doubtless been indefinitely valuable for the research of so many scientists and researchers. Even among my own office-mates, Cassini data has proved vital to respective thesis work:
>Alyssa’s work on Titan: https://alyssascience.wordpress.com/.
>Josh’s work on Titan: https://jjoshh.wordpress.com/.
This is the ultimate legacy of Cassini: Shedding light on the Saturnian system for scientists and researchers for decades to come. Before Cassini, nobody knew what Titan’s surface looked like nor what its environment was like. Before Cassini, nobody knew how dynamic Enceladus was (particularly its south pole). Before Cassini, detailed imagery — and eventually maps — of Saturn and its moons were largely the stuff of dreams. In many ways, Cassini was the Hubble of Saturn.
The above is just a couple snowflakes on the tip of the iceberg that is the entirety of the Cassini data and imagery collected during its mission, a mere couple minutes’ browsing through Google Images selecting some highlights.
Twenty years ago now, Cassini took off from Earth. I was only eight years old at the time. While Cassini may no longer be with us, thankfully many other probes and rovers are; of course, Science is a never-ending quest for knowledge and as such ever more space missions are being planned and carried out by space agencies worldwide.
The famous Dylan Thomas poem about growing old and dying has been passed about a lot the past couple days concerning the craft and its illustrious life, but for me, because I sometimes play League of Legends, it seemed fitting of a Star Guardian who is meant to shine bright yet fated to perish even more-so. In the end, I think both analogies are equally fitting….
Speaking of awesome planetary missions that have ended, I still have some MESSENGER imagery to work with and some craters to finish up cataloging for my own thesis project. I’ll definitely have an update once it’s all done!
After a month of failure to get Isis3 to properly render the MDIS-NAC files I downloaded from the MODE, success has, ultimately, been mine. Ailey crater, which sorely needed these high-resolution images because of a pesky shadow in the MDIS Global Mosaic that occluded the majority of the crater’s rim, floor, and melt deposit, can now be deemed “completed” in terms of its GIS file and now it can be analyzed for its melt emplacement-to-rim low characteristics similar to what has been accomplished already for 24 of my catalog’s “best” crater candidates. Alongside Ailey, around ten other craters, the majority of which need the high-resolution imagery to accurately locate their respective impact melt deposits, will also shortly be similarly analyzed and subsequently “finished off.”
Here’s what Ailey crater’s GIS file looks like now:
The next order of business is to summarize all 36 craters into the illustration pictured in my last post (A Mercurian “Hybrid Theory”?), and then do something similar for the craters in my catalog that are rayed.
All in due time….
24 of my 36 Mercurian craters have been almost fully analyzed at this point, and so a plot akin to what is present in Neish et al. (2014) and Neish et al. (2017) has been derived for these craters:
The number of “coincide” craters is small while the percentage of “~90*” and “>90*” craters is notably greater, as it is with Venus; however, there’s a large percentage of “Within 45*” craters — more like what is seen with the Moon.
It may be that the heavily cratered nature of Mercury’s surface is responsible for the “Within 45*” anomaly, but otherwise it appears the factor primarily controlling impact melt emplacement on Venus (direction of impact) is also predominant for Mercury.
This is where looking at rayed craters on Mercury becomes important, as the shape of the crater rays can give insight into the direction of impact. Here are a couple obvious examples on Mercury (using the MESSENGER Colour Mosaic map):
Assuming a crater’s rays are asymmetric (the Xiao Zhao image illustrates this nicely), one can simply mark the region where those rays are minimal to imply a direction of impact. Using Xiao Zhao as the example, the area where the fewest rays exist is roughly the NNE implying the projectile struck the surface from the NNE.
And then there are craters like Hokusai, that exhibit no such trait; all its rays are, more or less, symmetrical in their radial pattern. Does this imply the impactor that made Hokusai struck ground roughly vertically?
The remaining 12 craters of my catalog need MDIS-NAC imagery to supplement the mosaic imagery already present — unfortunately, said imagery for these craters is not the best, so the MDIS-NAC is meant to clear things up enough to resolve the melt pools and/or crater rim and floor. Once I can get Isis3 to cooperate with these image files, I can post another useful update!
Today, much of North America got to enjoy a rather nice-looking Solar Eclipse. Me included!
Viewing an eclipse in progress is best done using a telescope decked-out for the job. For example, at Western U such telescopes were available for public use during a special event geared to this eclipse — here’s what the eclipse looks like through one such telescope (we got 75% at “maximum” here in London, ON):
But, what if you have no such luck and would still like to catch a glimpse of the event? Here are some cool tricks virtually anyone can take advantage of the next time they find themselves in the right place and time for a Solar Eclipse:
Using your phone’s camera:
It’s a bit tricky, but one can achieve some fairly good results when done properly. Basically, you use your phone’s camera to take an “indirect picture” of the eclipse. If you point your phone’s camera directly at the sun (this is the tricky part, because you need to angle your phone without also looking upwards lest you accidentally look directly at the sun), at the proper angle you should see a disk-like “reflection” in your image hovering near the sun itself. Depending on how far along the eclipse is, the reflection should appear as if it has a “bite” taken out of it; this is the eclipse! Here’s an example of what I’m talking about here:
The hand-made “pinhole camera” method:
Using your hand, make an “almost-fist” with it such that the sun’s light can still pass through the gap in your fist and onto the ground below. During the eclipse, it should appear as if a crescent-shape of light is cast onto the ground behind your fist. Below is an example (this method’s comparatively less tricky, since you don’t need to avoid looking up in order to ensure a good result):
If you happen to own a telescope of some kind…:
If you own a telescope, but not the resources/know-how to set it up for an eclipse then fear not! Your as-is telescope is still sufficient so long as you also own a square of cardboard. Using the cardboard, orient your telescope towards the sun (again, don’t use your own eyes!); once properly oriented, the disk should show up on the cardboard — hopefully being occluded by the Moon! If your telescope has a pinhole lens attachment, installing that to your telescope should make the resulting image clearer.
MDIS-NAC images have been downloaded for all the craters in my catalog that have useful NAC files worth downloading — all except two, if I remember correctly.
But, over half of my craters are already fit enough to be analyzed for melt and rim-low locations and so that is what I attempted to do this past week or so. Below is the gist of what I’m doing here:
Using the grid-like object, superimposed over the original GIS file, I mark out where the highest concentration of melt (in purple) is as well as the most likely location of the rim-low (in red). In the case of Balanchine crater, above, the location of this melt pool is in the W-WNW wedge, while the rim-low can be found within the NW-NNW wedge; this means that the melt is predominantly located within 45* of the rim crest low.
A number of craters need the MDIS-NAC for better locating the melts (and in a couple cases the crater floor), so that will be my next task at-hand. Then, I can add grids to those craters as well and fix up any hiccups that the already-completed craters had during this first run of mine through this process.
For me and my supervisor….
What I’ve done so far:
>>GIS files for most of my 36 craters have been created, with rim, floor, and melts shapefiles made for each.
>>MDIS-NAC files have been downloaded for all named craters (around 19 craters).
What I want to complete by September:
>>Download MDIS-NAC imagery for my unnamed craters and render all MDIS-NAC files in GIS to aid in completing the handful of crater GIS files that remain incomplete. [1 week + 1 week, max]
>>Complete all rim, floor, and melts shapefiles for remaining craters. [1 week, max]
>>Acquire MDIS-derived DTM map(s) from Preusker et al. (2011/2017/2017) for any outlying craters that still exist — if time permits, perhaps even add some southern hemisphere craters to my “catalog.” [1 week, max; 1-2 weeks for S.H. craters]
>>Conduct a statistical analysis on these craters, locating where the majority of melt emplacement is w.r.t. each crater’s rim crest low and then compare my results to the Neish et al. (2017) results. [1-2 weeks, max]
>>Analyze all the rayed craters in my “catalog” for evidence of impactor direction, perhaps using MESSENGER’s false-colour mosaic. [1 week, max]
>>Hope to begin to write-up my thesis come September (the above should take 6-8 weeks to complete, assuming no hiccups or what-not along the way).
I hope to have completed the first “to-do” objective by the time I draft my next blog post here.