Sorry Alyssa, I can’t not talk about the election
Before, I get into my research, I have to talk about the most unfortunate and depressing turn of events that was the Presidential election. Let’s start with education, or the lack thereof. Trump has made it very clear he intends to gut, if not close, the department of education. You can’t miss the irony that the uneducated voting for a man that would only worsen our already dropping position in science and math rankings worldwide. It’s like the very embodiment of willful ignorance. Looking beyond education, the future for the CDC, the EPA, and so much more is at risk. Who does Trump pick but Myron Ebell, a top climate skeptic, to lead the transition for the EPA. Or how about trumps ability to pull the us out of the already weak Climate deal in Paris? I haven’t even mentioned the fact that he thinks Climate Change is a hoax perpetrated by the Chinese.
This is who we voted for. There is a lot more that can be said about our future in Science with Trump. The one saving grace may be his position on NASA, but I’m being generous. He wants to expand the exploration sector of NASA. That doesn’t help me, but it’s a necessary and useful part of inspiring more exploration and science. Except, he said it as though he would redirect from earth based activity. That could mean anything (e.g. less money overall but a larger fraction on exploration, same money but forcing focus on exploration and not on earth science, etc.).
About a month ago, Catherine tasked me with forming a global mosaic of Titan much like the one featured in this image using the Radar Mapper Visual and Infrared Mapping Spectrometer from the Cassini. This has involved several steps, so lets go through each.
Before I got started, Alyssa and I met with Catherine to review how to convert files to ISIS format, then how to project, then how to mosaic. We had already discussed most of this. the key aspect was how to create a loop that can cycle through multiple images. I’m glad she helped us form the code first. It didn’t completely register at first, but after multiple cycles of using and editing the code, I’ve got a good understanding of where each component came from and how to recreate it or something similar.
There are still some issues. There were some issues using the same code on the same type of files. There were maybe 5 files for a couple resolutions that didn’t want to mosaic after being projected the same way with the same code as all the other files of the same resolution. I found that manually removing those files fixed the problem. For this mosaic, the only resolutions we care about are the 3 highest, G, H, and I. These are 64 pixels per degree (ppd), 128 ppd, 256 ppd. There wasn’t an issue with G or I. Catherine made a couple suggestions on how I might can make some changes to get around it by checking the raw file in text editor. I haven’t had a chance to do this yet, but I’ll talk about these files more later on.
Retrieving RADAR data
Data was retrieved from the Planetary Data System (PDS) using the Cassini Radar Volumes (image above). Is used the Basic Image Data Product (BIDR) files. These are single pass files, calibrated and gridded using SAR image data. These are produced by JPL in full-resolution floating point format.
This has ~200 different volumes of data, but not all have BIDR products. I went through and opened each set with BIDR, and found 51. Each set has a range of files. I searched through the Cassini Radar user manual and searched for other sources of information, but I still don’t know what each component of these data sets mean. I know it lists the lat and long as well as the resolution using D, E, F, G, H, and I, I being the highest and D the lowest. That still leaves the first part of the label. The examples Catherine showed us used “BIBQ.” I was pretty sure that was the right label to use, so I pulled these. I mention this because I should probably understand why we used it.
Once I identified what files I needed, I developed a method of downloading them. I decided to sort the files before I tried to download them. To do this, I copied and pasted the entire page text of each archive folder (image above) from the 51 BIDR folder I mentioned before. Then I pasted this in excel. Excel has a useful feature called “Macros” that let you run a set of instructions in excel on command. It’s particularly useful because you can record your
actions once and it can record it as a macro code that can be ran again. I copied the text into excel, and the consistent format in the archive folders made it easy enough to sort a
given list out by starting label (because we care about BIBQ), Resolution, Lat, Long, and file type (Zip, lbl), and flyby info. It filters the data, then I manually move it to a new list of the data we’re interested in. This makes it easy to sort by resolution, position, and file type for the entire data set. The hyperlink also carried over meaning it was easy enough to go to each file.
I sorted the files by resolution. Then I begin fiddling with the code to try and convert the images. I converted the files to cub files then to map files projected to the same simple cylindrical projection but with resolution specific resolutions. As I said before, I had some issues mosaicing E, D, F, and H. Each of these had 3 to 6 files that I had to remove to avoid getting map matching errors. The error was in mosaicing the individual resolutions. Again, I haven’t had a chance to figure out why the files are messing up, but I’d argue the files aren’t very useful anyways.
I ran a mosaic for each resolution at their native resolutions.
I had to learn, or rather be reminded, that these mosaics won’t mosaic themselves because they are different resolutions. I’m working on changing the resolution, but the processes is slow and takes time. I also didn’t realize that you apparently can’t convert/project lower resolutions to higher resolution files. I did this, but it wouldn’t mosaic. I thought Catherine suggested using a size like 128 ppd, but even that is larger than G (64 ppd). So that makes me wonder if its something else that is the problem that I may be missing. I just don’t think thats the case because the mosaic didn’t produce an error until it moved from G into H files, and removing the first file produced an issue with the second. That was hen I decided to move on to using the G resolution for the mosaic. Results in progress.
The next step for me is to start using Tecton, the finite element analysis program I’ll be using to model craters for my research. My work so far is just trying to understand how to install the program. It doesn’t seem straight forward. The pdf file accompanying the file doesn’t go into. It’s about copyright and ownership. It mentioned it was a fortran code. I don’t have experience with that. Still, I tried to figure out how to install fortran. There seems to be a lot of different types out there. I found the most basic I could find for Mac and installed it. I haven’t made anymore progress. Catherine, how much do you know about Tecton. I don’t see a lot about it online, but Zibi references Melosh 1980. I’ll look into that before I email Zibi about it.
The first draft of our research propasal was due for geophysics seminar. I don’t want to post my entire thing, but I think it would be worth discussing my research problem and objectives.
- The parameters of Titan are identified using existing literature.
- Surface properties must be identified based on the composition and temperature at the surface.
- The composition, temperature, and structure of the interior changes with depth. These conditions and how they change must be to identified.
- Spatial and temporal variations must be noted and considered.
- The identified parameters will be used to model the viscous relaxation of existing craters.
- The parameters are to be varied to much greater and much less than those observed to consider the overall weight of each parameter.
- The actual parameter limits ascertained during the first objective will be implemented to constrain the viscous relaxation to the realistic limits.
- The results will be compared to current state of the surface to further constrain the identified parameters.
- A long-term objective of this project is to model the exogenic processes that influence the surface morphology.
- Degradation will be modeled combining the exogenic processes with active relaxation of the topography.