Today we have a guest blog by JPL research scientist Laura Kerber, one of our lead researchers on Planet Four: Ridges . Laura studies physical volcanology, aeolian geomorphology, wind over complex surfaces, and the ancient Martian climate,
Hello Ridge-Hunters! We have been finding lots of ridges in Nilosyrtis Mensae, and I wanted to give you a bit of an update on our progress. Here is a map showing the images that we have looked through (blue), the places where I thought there might be ridges before the project started (circled in orange), and the spots where you have actually found ridges (purple dots).
As you can see, most of the ridges were found in the southeast portion of the search area. I took a look at the outliers, and they aren’t the kind of polygonal ridges we are looking for—meaning that all of the polygonal ridges we found have been in a pretty restricted area. Here is a close-up of that area:
There are a couple of important things that we have already learned from what we’ve found so far. First, we can see that the ridges aren’t correlated with craters. One of the early theories about these ridges was that they were breccia dikes—that is, dikes of broken-up material that was forced through surrounding terrain during a violent impact event. The presence of polygonal ridges both in craters and on the inter-crater plains makes this hypothesis seem less likely.
Here are some great ridges that you found on the intercrater plains:
And an even closer close-up:
We also want to know whether or not the ridges are correlated with valley features. At first glance, it looks like valleys and ridges aren’t correlated, because there are plenty of ridges in the inter-valley plains, and valleys like Auqakuh Vallis that don’t have a lot of ridges near them:
Upon closer inspection, we can see that the ridges are correlated with what we call an “etched” terrain—terrain that has been heavily eroded, leaving bits and pieces of the terrain that came before it. The southern part of Auqakuh Vallis is dominated by etched terrain, and we can even see that part of the valley has been inverted by erosion (what was once the valley floor is now standing higher than everything around it). We can also see that the western branch of Auqakuh Vallis has cut this positive feature, meaning that it was active long after the eastern branch stopped flowing. There were a lot of ridges identified both surrounding the river deposits that make up the top of the inverted Auqakuh Vallis channel and around it. This may suggest that ridges are preferentially forming in old river sediments:
But why aren’t there ridges further north along Auqakuh Vallis?
Actually… there are! Here is an image further north along the Vallis. We can see that northern Auqakuh Vallis cuts through a ridge-containing unit, but in most of the surrounding area, the ridge-containing unit is capped by a unit with glacial morphology that hides the ridge unit from view:
Our current hypothesis: The ridge unit formed before or at the same time as the valleys were being cut. Afterwards, glaciers and ice sheets covered the area and deepened and widened the valleys. The glaciers covered the northern Auqakuh Vallis region and most of the terrain north of it, including the western part of the study region.
The next group of CTX images extends our search area to the east. This is the area where this type of polygonal ridges were first mapped, before we had CTX images covering the entire area like we do now. The first mapping project (in 2006) identified ridge lattices inside mostly inside craters, leading to the hypothesis that they were impact-related breccia dikes. The second project (in 2013) mapped ridges along the Nili Fossae trough system, leading those scientists to hypothesize that the original fractures may be related to the trough system. Our study of the ridges to the west has been offering an expanded context for these hypotheses. The other special thing about this region is that we will be covering two of the three remaining potential landing sites for the next NASA Mars rover, called “Mars 2020”. Mars 2020 is carrying a suite of instruments that it will use to search for habitable places on Mars as well as organic material. The new rover will also carry a drill that it will use to take samples of many different rocks and cache them in tubes for a future mission to bring back to Earth. Wouldn’t it be great if they could bring a bit of ridge back for us?
We’ve got some good news for your weekend. We’ve got brand new images on Planet Four: Ridges, expanding further south and east of our original area. More area covered, gives more opportunities to find unknown polygonal ridges. The more ridges we find, the better statistics we will have when we compare to other orbiter data sets to see if ground water is the main source for how these ridges form. You can see where the search area is in comparison to our first data set below. The cyan show the footprints of the new CTX images on the site, the magenta are the footprints of the CTX images we had uploaded at launch. We thought the magenta area would take a year to search, so we’re thrilled that we can expand the search radius. Thanks for your time and your contributions. We really appreciated.
We’ll have some more blog posts in the coming days and weeks to talk more about this new search region.
Dive in and search for polygonal ridges today at http://ridges.planetfour.org
I’ve been working on getting some preliminary locations of polygonal ridges in the completed Planet Four: Ridges subject images. I thought I’d share. Here’s locations where 7 or more volunteers who reviewed a subject image and said there were ridges present. We have 10 people review each of the subject images on Planet Four: Ridges.
I’ve made some figures to show the locations of these subject images. Below are MOLA shaded elevation maps with the CTX images we searched outline in blue. The red boxes are the prelminary locations of polygonal ridges, based on the criteria discussed above,
And zoomed in more
We’ll use take these locations and eventually compare to the maps of minerals to further explore the formation mechanism for poylgonal ridges in the area. Stay tuned. More to come as we finish the next set of images live on the site. Help classify an image or two on Planet Four: Ridges today at http://ridges.planetfour.org
We’re now 60% through the third set of CTX images on Planet Four: Terrains. We’ve started to think about where we want to search next. We want to continue to fill in the area searched from -70 N latitude to the Martian South Pole. I’ve been coming up with the CTX image selection since the launch of Planet Four: Terrains. I wrote a code that goes through the list of publicly available CTX images and tries to pull out a well balanced distribution of ice-free CTX observations across specific latitude and longitude bins. I thought I’d share my proposed set of new CTX images to search. I’ve sent this list of images to the rest of the science team, and I’m awaiting their feedback. The new set if accepted by the team, will fill in gaps in our coverage and especially between -70 and -75 N latitude. When we have a final list of CTX image to search after dataset 3, we’ll update you here on the blog.
Color Code for figures below.
Red= first dataset at launched and used in our first paper
Green= second dataset
Magenta = third dataset that expanded out to -70 – currently being reviewed on the site
Gray = 4th proposed set of CTX observations to search
The CTX image outlines are overlaid on an elevation interpolated map. Latitude and longitude lines are in 10 degree intervals for above and below. The colors below represent geologic units, but for this comparison we’re focusing on spatial distribution and coverage. More details can be found here
It is my great pleasure to announce that we have written up the first science results for Planet Four: Terrains in a science paper. After months of writing an analysis we have a final draft ready, and last night I submitted it to the journal Icarus to be considered for their Mars Polar Science special issue.
Right now the manuscript is in the hands of the editor. After some checks, the paper should be sent on to two anonymous reviewers. In what we call the peer review process, these reviewers are independent researchers in the field who read the paper, critique it, and provide feedback which the I will have a chance to respond to and make some or all the recommended revisions to the paper. This process can have a few rounds of iterations with the referee. Ultimately, the referees will recommend to editor of whether the paper merits being published, and the editor makes the final decision.
So now we wait. The manuscript is in the hands of the editor at Icarus who is likely selecting and contacting possible referees. In a month or so we should get back the first round of reviews. I’ll keep you posted here on the blog. So stay tuned! This paper focuses on the distribution of spiders and swiss cheese terrain from the data on the site at launch. We’ve also included analysis of some of the HiRISE observations taken of some of these new spider locations. I’ plan to write a fully summary of the paper results once the paper is hopefully accepted in a few months.
Thank you to all of you who have participated in Planet Four: Terrains. We could not have done this without you. We appreciate the time and effort you put into this project. Thank you for collaborating with us.
We also want to thank the Zooniverse team for giving the research team early access to their Project Builder platform to build and design Planet Four: Terrains.
Planet Four: Terrains is not finished. This is just the beginning. We’ve expanded out search more areas way from the South Pole. Many of those images are in need of review. So jump in and help explore Mars today at http://terrains.planetfour.org
I wanted to point out some features you might have noticed in the Planet Four: Ridges images. Dark wiggly blobs as shown in the images below are actually sand dunes on Mars.
We’re showing images from orbit, but to give you a sense of what some of these might look like from the ground, here’s a selfie of Mars Curiosity at “Namib Dune”, part of the informally named Bagnold Dune Field located in Gale Crater. I learned recently that on Mars, sand dunes are black because they are made of ground up basaltic lava rocks, just like black sand beaches of Hawaii are.
Today we have a guest blog by JPL research scientist Laura Kerber. Laura studies physical volcanology, aeolian geomorphology, wind over complex surfaces, and the ancient Martian climate,
The surface area of Mars is almost the same as the area of all of the continents on Earth. Only a tiny fraction of these vast, untouched lands have been explored by rovers. Of the rest, much of it has still never been seen up close by human eyes. Today we’ve launched Planet Four: Ridges, and we are asking for your help to explore a particularly interesting part of the Red Planet. The goal is to find polygonal ridge networks, which are intersecting lattices of thin ridges enclosing polygonal shapes.
Some of these ridges can be up to 50 meters tall, and from the surface would appear like the ramparts of an enormous fortress. Networks of ridges are usually formed via the filling of fracture networks either with lava, wind-blown sediment, or mineral deposits from circulating ground waters. These fractures are then transformed into ridges as the softer units around them get eroded by the wind. Your classifications on this site will help researchers find these networks and compare them to distributions of other features, such as mineral signatures, ancient valley networks, and dried up lakes. The images you see here are taken using the mid-resolution (6 meter per pixel) Context Camera (CTX) in orbit around Mars. Each participant views portion of images and decides whether or not there is a polygonal ridge network in the frame. We collect together everyone’s views on each image and this helps us find new ridge networks to study. The ridge networks can be subtle, but human eyes are well suited for pattern-finding, which is why we rely on you over computer algorithms.
More than 3.5 billion years ago, the climate of Mars was much different than it is today. The surface of Mars shows evidence for hundreds of lakes, and thousands of kilometers of flowing rivers. During this time and earlier, warm groundwater may have circulated in the Martian subsurface, potentially providing a protected home for early Martian life. One piece of evidence for groundwater during this period is the presence of clays that are deep in the crust (often visible in the central peaks of impact craters). Another is the presence of mineral veins, which are formed when warm water carrying elements in solution deposits minerals on the walls of fractures. Hot water or steam can also alter wall rocks of fractures, causing the walls to harden compared with the surrounding material. Later, after the crack cools, the minerals become harder than the rock types that surround them, so that as the surrounding unit get eroded by the wind, what was originally a fracture becomes a ridge.
Not all polygonal ridge networks are formed due to circulating groundwater, however. Sometimes open cracks on the surface get filled with windblown dust and sand, and that part gets preserved. Lava can also fill up cracks, either as it rises through the subsurface as magma, or if it is flowing along and drips into a fracture network. Finding all of the ridge networks on Mars helps us untangle which networks were formed by which process, all the while learning more about the intriguing wetter period in Mars’ history. This project focuses on the Eastern Arabia Terra region of Mars, where several ridge networks suggestive of mineral veins have been found.
As the project continues, we hope to share more background information on these interesting features here on this blog. Meanwhile, why not go find some ridge networks? Visit http://ridges.planetfour.org to start looking.
January 8th, marked the 4th anniversary (well at least in Earth years!) of the launch of the one and only original Planet Four. We wanted to thank you for being on this journey with us for the past four Earth years. Our first science paper seems to always be delayed, but I and the rest of the science team are dedicated to getting this paper out the door. The science team is virtually meeting on Wednesday to discuss what I hope is the freezing of the development of the classification clustering algorithm. That’s the hurdle in our way, and over the past Earth year Michael has made great strides dealing with the major issues we needed to tackle to get the science from your clicks. Thank you for your time and effort on the site. We still need you, and new data from Manhattan Season 5 is now live on the site. So go check it out and classify some fans and blotches at http://www.planetfour.org.
Planet Four has been able to show that a citizen science approach beyond crater identification with Mars orbital imagery works. The science team was invited this past fall to showcase Planet Four at a workshop focused on citizen participation in Mars exploration hosted by NASA Headquarters. Planet Four’s successes, has spawned other Mars Zooniverse citizen science projects: Planet Four: Terrains (which has already produced results with Mars Reconnaissance Orbiter pointing HiRISE and new locations on the Martian South Pole) and a birthday gift if you like that is coming tomorrow! Stay tuned to this space for more tomorrow! We can’t wait to share this new endeavor with you all.
Thank you for the past four years and onward to Year 5!
A quick update on Planet Four: Terrains. I’m working on the first paper draft and planning on submitting it to a science journal by early February with any luck. Currently the draft is being iterated on; I’m incorporating comments and feedback from the rest of the science team. The paper focuses on the distribution of spider features on the South Pole based on Planet Four: Terrains assessments. So stay tuned for more on that over the coming months.
In the meantime, I’ve also processed the subject images currently retired from the newest set of images on the site. We’ve found interesting areas with spiders and baby spiders that we’d like to get a closer look at. We’re hoping that HiRISE will image these over the coming months. The days on the South Pole are getting shorter. May 5th 2017 marks the official start of Southern Fall Equinox. In a few months time, we’ll have to wait approximately 2 Earth years for an opportunity to image interesting regions of the South Pole with HiRISE found by Planet Four: Terrains.
Processing the retired subjects from the current set of CTX images on the site, we found four new regions of interest thanks to your collaboration that we want to take a better look at. We have requested HiRISE imaging. So the race is on to get through as many of the P4: Terrains subject images as we can before there won’t be enough sunlight for HiRISE observations. If you can spare some time, place help classify an image or two for spiders, baby spiders, channel networks, swiss cheese terrain, and craters on http://terrains.planetfour.org
Thanks to all your help, we’ve completed the review of the Season 4 observations of Giza, Ithaca, and Macclesfield. We have new observations from Season 1 from a two different areas around the South Pole now uploaded and live on the site. These areas are nicknamed Starfish and Caterpillar for the spider morphology that have been seen in those areas. Caterpillar is much further away from the South Pole than some of the areas you’ve reviewed here before.
It will great to see how the numbers and sizes of fans and blotches in these two areas compare to Manhattan, Macclesfield, Inca City, Ithaca, and Giza. Dive into these new images today at http://www.planetfour.org