Another Day, Another Project: Identifying and characterizing all of Titan’s craters using Cassini’s COMPLETE data set.

I’ve another project to work on in addition to my original project studying the relaxation of Titan craters. If you’ve followed along, you’ll know there have been a number of issues trying to get the Fortran code to run and take the input files. Catherine doesn’t have a lot of background with it, and my collaborator is very busy with a number of other projects. Unfortunately, this has made for a very slow project. We aren’t casting it aside, but it’s being moved behind my new project of identifying and characterizing all of Titan’s craters. This has been done for most of Titan’s craters. However, we’ve now completed the final Titan flyby and have all the data we are going to have, so my task is to develop a systematic approach to search for all the craters that have been discovered and for any other possible craters. Then, I will use the topography data we have using Sartopo data to characterize crater size, depth and its other characteristics. Sartopo data is topography data obtained by calibrating overlapping radar flyby profiles that give the topography in the region where it overlaps.

I’ve begun by developing an easy system of functions to call the Sartopo data for a given crater. With the function ‘crater_elevation.m’ and the data file ‘sartopo_data.mat’ you can easily call the data profiles in the region by inputing the center latitude and longitude with the crater diameter.

For example, if we use the center lat and long of Menrva (425km) we’d put into matlab the following:

>> crater_elevation(19.6,87,425)

It returns a map of the region with the radar images overlain with a colorize height profile where ever there is sartopo data (Figure 1).

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Figure 1: A map of the region of Menrva (lat: 19.6, lon: 87, 425km) with the a radar mosaic overlain with a colorized height profile where ever there is sartopo data. Height is in meters NOT kilometers.

A similar map is shown with each sartopo profile colored by profile number (Figure 2). This is derived from the sartopo data file names. SARTOPO_T00AS01_B12_V02_170315.CSV is 0000112, or 112 when inputed into matlab. Where the number is the fly-by (in this case fly-by A is 000), then the number after S and the number after B. The numbers after V are unchanging. The purpose of this plot is to just give perspective to where each profile is on the map.

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Figure 2: A map of the region of Menrva (lat: 19.6, lon: 87, 425km) with the a radar mosaic overlain with sartopo profiles colorized by profile number.

All of the profiles are shown along the distance of their own profile track (Figure 3). You can use this to identify which profiles are of interest for further studying.

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Figure 3: Each sartopo profile along the distance of the profile in km (x-axis) and the height of at each point.

The next step is identifying the crater depth and rim height and possibly width and height of central peaks/pits. I’m currently developing a code that will take the center lat and long and the crater diameter. It assumes you know the diameter, but I’m only using it to tell the code where to look for data. Once I’ve done that, I’ll go about finding where the rim is highest on each side, and the crater diameter is just the rim to rim distance. The function is still in development, but right now it also takes a vector of sartopo profiles that you want it to calculate the crater information for. I’ve added a step that allows the function to run without that defined. It will determine which profiles are inside 1 radii from the center lat and long and use these profiles.

If I make progress before the end of the day, I’ll add more info. The current plan is to find the center of each profile (from rim to rim of ~1.5 of the defined diameter) then look for the max height on either side. Then look for a point of flat lowlands between these two points. I suspect we may get profiles that run along the edge, so you may see a profile that forms like a V. I’ll try to develop a way to omit these profiles because it doesn’t map the inside of the crater. Another issue I’ll have to deal with is that the profiles don’t run through the middle. Even in Figure 2, profile 30112 doesn’t go exactly through the middle. The current idea is use the crater center thats given to the function and a bit of geometry to calculate the data for directly through the center. It’ll be interesting to see this done for a crater like Menrva where we have 4 solid profiles to do the calculation on.

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Planetary Field School

Over the course of 12 days, we explored parts of Arizona, Utah and Nevada for the planetary field school. I took a range of photos for each stop and have/am posting each set on facebook. Here, I’ll pick one and offer a short description, but given the large number of sites, I’ll keep the descriptions short.

Day 1

Traveling

We began by taking a late bus to Detroit. The weather was dreary and not the best way to start the trip. Luckily, that didn’t last. We met up in the Las Vegas Airport around lunch before driving nearly 4 hours to Mather Campground. I won’t talk much about camping, but we changed location everyday, and I posted pics from all our stops on Facebook if you’re interested.

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Las Vegas Airport
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Mather Campground

 

Day 2

Grand Canyon Hike

We spent the first half of the day hiking down the Grand Canyon, maybe halfway down. The grand canyon doesn’t need much background. Its creation was related to a combination of fluvial erosion, uplift, and the types of rocks in the region.

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Red Mountain

Red mountain is a cinder cone that formed ~3/4 Ma.

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Day 3

Lava River Cave

My stop was the lava river cave. The cave is the result of cooling of the outer shell of a lava river encasing the lava and insulating it. This allows lava to flow further, posing increased risk on locals. These are particularly interesting because they’re capable of maintaining constant temperatures, humidity, and other environmental factors. This makes them a prime spot to search for life on worlds like Mars. They also make for a great base on Mars or the Moon to protect from cosmic rays.

Elden Mountain

Elden mountain is a silica volcanic dome in the SF peaks, close and perhaps a part of, the stratovolcano in the region. This stop came after LRC which was such an amazing experience. I remember thinking after the GC hike, why are we doing another stop, how can we compete with the GC? RM was more impressive than I expected. I had the same experience here. LRC was amazing, and in my opinion lava domes aren’t the most exciting features. That said, I think this was the stop I started to realize even the most mundane stops had a lot of awesome things to offer.

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San Francisco Volcanic Field/ Peaks/ Glaciation

We saw a variety of formations such as cinder cones in the SFVF and even a stratovolcano (top right) thats responsible for the SF Peaks (bottom), and we ended day 3 but looking at evidence of glaciation in the region (top left).

 

Day 4

Grand Falls

Before the trip we had an unknown location that we had to map with a satellite image. This was a our chance to see how well we predicted what happened. Grand falls is a river that was a later altered by a lava flow that went into the river channel changing the region.

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after the water fall
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before the water fall

Rattle Snake Crater

RSC was a surprise stop, where we tried to repeat what we did at GF without the preliminary analysis. It isn’t really a crater. Its actually a heavily altered Maar Crater. A maar crater or volcano. A MC/MV is formed when a pocket of magma interacts with water, turning the water to vapor, creating a fast and large increase in pressure, exploding to create a crater like structure. There were two sides of this. I felt very proud to climb to the top of one side (and was the first :)). Of course, it was hardly the biggest hike we did, but I loved it nonetheless.

Day 5

Meteor Crater

Meteor Crater is iconic, forming about 50ka. Just outside of Flagstaff, MC is an impact crater about 1.2 km in diameter and 170m deep. We saw a lot of craters that were not craters, so it was nice to see a confirmed crater. Gavin got to lead this talk (see pic).

Sunset Crater

SC is a cinder cone. At ~1ka old, it was one of the youngest structures that we saw. It’s a part of the San Francisco volcanic field, and you can see it in one of other photos.

Strawberry Crater

We camped at SC, but we also had a chance to hike up it. SC is another cinder cone, not a crater. At over 300m, its a decent hike. I tried to hike up it, but I couldn’t keep up. I ended up hiking part way then going back, but a few others made it all the way to the top.

Day 6

Agathla Peak

This is a volcanic plug or intrusion that feed some type of volcanic structure. Oz says we suspect it feed a Maar Volcano, but he was unable to explain why when I asked how we know.

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Goosenecks State Park

This is one of the best examples we have of a meandering river.

Day 7

Upheaval Dome

Is it a complex impact crater or a salt diaper? At ~5km in diameter, its thought to be an impact crater, but it is indistinguishable from a salt diaper (where less dense salt makes its way up to the surface). Past authors have claimed to have found evidence of shock, but the evidence is scarce.

But aside from the science, we hiked in and it was exhausting. Just look at the stats (it was a little longer then it says because I accidentally paused it for a bit).

Day 8

Day 9

Onion Creek

A confirmed salt diaper that we used to compare to upheaval dome.

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Green River

Overlook at sapping valleys and paleochannels

Crystal Geyser

A man made geyser due to drilling and creating excess pressure from CO2. It is a “cold” geyser but it looks just like a traditional geyser we associate with early life on earth and possibly on other worlds.

San Rafael Swell

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Day 10

Marscvale Volcanic Field

Coral Pink Sand Dunes

This was probably the best stop of the trip. It was like playing in a big sand box. Because we spent the night here we were able to take moonlight photos too!

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CPSX formed in the moonlight

Day 11

Inverted Topography (St. George)

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Gypsum Veins

Water rich in minerals is pressurized in the ground and overtime forms these veins of gypsum.

Petrified Sand Dunes

Similar to the coral pink sand dunes, these are older, petrified into rock. This was a great contrast to the CPSD and was  beautiful site to see. Although, I was careless, given that it was the last stop, and let myself get sunburnt :-/.

Day 12 and 13

Vegas

Flight was canceled, so we got to rebook and planned an amazing trip in vegas! Went out and it was awesome. I gambled for the first time, and I stuck to my budget, spending half as much as I had allowed myself too. It was fantastic. I was so happy it turned out like this.