Today we have a post by Candy Hansen, principal investigator (PI) of Planet Four and Planet Four: Terrains. Candy also serves as the Deputy Principal Investigator for HiRISE (the camera providing the images of spiders, fans, and blotches seen on the original Planet Four project). Additionally she is a member of the science team for the Juno mission to Jupiter. She is responsible for the development and operation of JunoCam, an outreach camera that involves the public in planning images of Jupiter.
We have discovered something very interesting in the number and size of the fans that show up on the south polar seasonal cap every spring, that you are measuring. It turns out that in springs following both global and regional type A dust storms we see a lot more fans than normal for that time of year. This picture compares sub-images from 7 Martian years taken in “Manhattan” at solar longitude 195-197. The position of Mars in its orbit is the solar longitude (“Ls”), and southern spring begins at Ls 180 when the sun crosses the equator and heads south. Mars years 29, 30 and 33 have visibly more fans. There was a global dust storm in Mars Year (MY) 28 that started in early summer. Intense Type A storms, which are regional and centered at high southern latitudes, took place in MY29 and MY32. It looks like the spring after these storms have large numbers of seasonal fans.
Although the visual impression is powerful when these images are compared we can go beyond that now, thanks to the Planet Four fan catalog that your work has populated. We can quantify the differences. We used the MY29 an MY 30 catalog that we’ve published this year in our first paper, and also newly generated catalogs for Manhattan for MY 28, MY31, MY 32. Instead of just saying “there are a lot more fans” we can say “there are over twice as many fans” in MY29 and MY30 compared to MY28, 31 and 32. We do that by querying the catalog – an example is shown below. The plot below shows numbers of fans as a function of time in the spring and we can compare 5 years at Ls 195. I had the pleasure of presenting this (your!) work at the 2019 Lunar and Planetary Science conference last week in Houston, Texas.
To confirm that Type A storms are playing a significant role in the composition of the seasonal ice sheet that produces the carbon dioxide jets that bring up the dust and dirt that create the seasonal fans and blotches, we need to look at the number of seasonal fans and the area covered in MY33. We only have classifications for Seasons 1-5 of the HiRISE seasonal monitoring campaign (MY28-32). This brings me to my request: We would really like to have Planet Four measurements for MY33. We have uploaded the images, so it is ready for you to process. We would like to thank you in advance for your generosity with your time. Once those measurements are in we will be ready to write our next paper documenting these findings in a peer-reviewed scientific journal. As you know we have published one paper already and two more are in progress. This is a significant result, and we could not have done this without all of you.
Help classify the new images of Manhattan today at http://www.planetfour.org.
Greetings from Knoxville, Tennessee. Earlier this morning, I presented our first catalog and early results from comparing the fan directions over two Mars years at the American Astronomical Society’s Division for Planetary Science meeting. Here’s my slides.
The science team is working on ticking off the last things on the todo list before we can submit the first Planet Four paper. Michael is in the last stages of making edits and changes to the paper draft. We’re nearly over the finish line. While Michael has been working hard on the manuscript text and catalog files, we’ve also been iterating on some changes to the figure Anya made that shows all the locations making up the Seasons 2 and 3 monitoring campaign that are part of our fan and blotch catalogs based on your classifications. I thought I would share some of the versions Anya made:
It’s really exciting to think back to when this project started in 2013 and now see this plot, where I can say we have fan and blotch identifications for HiRISE images taken in Season 2 and 3 Southern Spring/Summer for all of these plotted points.
Today we have a post by Dr. Candice (Candy) Hansen, principal investigator (PI) of Planet Four and Planet Four: Terrains. Dr. Hansen also serves as the Deputy Principal Investigator for HiRISE (the camera providing the images of spiders, fans, and blotches seen on the site). She is also a Co-Investigator on the Ultraviolet Imaging Spectrograph on the Cassini spacecraft that orbited around Saturn until the end of its mission last year. Additionally she is a member of the science team for the Juno mission to Jupiter. Dr. Hansen is responsible for the development and operation of JunoCam, an outreach camera that will involve the public in planning images of Jupiter.
Last week marked the 5th anniversary of Planet Four’s launch. Five years ago, I was sitting in a meeting only partly paying attention. I was focused on the brand new Planet Four website – it had just gone live and took off like a rocket. I kept hitting refresh, enjoying each of the new introductions in the “Hello Everyone!” chat.
Now we have a community. When I lurk (which I still love to do) I recognize the names – Pete J, wassock, Kitharode, angi60, p.titchin, …. My heartfelt thanks go to Meg Schwamb for engaging with our citizen scientists on a regular basis!
Five years on you have measured fans and blotches in over 5 million HiRISE image cutouts. We’ve applied statistical analysis and turned that into a catalog. We can now query the catalog (where is the longest fan? Which way is the wind blowing in Manhattan at the beginning of spring?) We are very close to submitting our first paper describing the catalog with samples of potential results that can be pulled from it. The second paper is already shaping up with comprehensive results for wind directions throughout spring – these results are the gold we were hoping for when we started this citizen science project. The vision we had in the beginning is now coming true.
Right now we use models to understand Mars’ meteorology. In order to test the models we need data – wind markers. The atmospheric modeling scientists are very excited about seeing our results – results we wouldn’t have without your efforts! Thank you as always for your generosity with your time!!
The American Astronomical Society’s Division for Planetary Sciences meeting was held last week in Provo, Utah. We presented results from Planet Four: Terrains, but it wasn’t the only Planet Four project represented. There was an update on Planet Four. Chase Hatcher attended the meeting ready to talk about Planet Four. Chase is, a student at the University of North Carolina at Chapel Hill and he spent this past summer working in Colorado with Anya and Michael on Planet Four analysis.
Chase presented a poster on his work at DPS as well as some of the other progress on the Planet Four data analysis we’ve made. Thanks Chase for all the hard work and for representing Planet Four. You can find Chase’s poster below.
Greetings from Provo, Utah. I’m here to present science results on Planet Four: Terrains among other things. The DPS is now trying out a new set of poster presentations using large touch screens, which they are calling iPosters. My abstract was selected for an iPoster. This means you can currently explore view and my iPoster online here. Enjoy!
Michael produced these great plots below showing the fan and blotches identified in each subject image showing 6 overlaping subjects. We have overlap to ensure that we don’t miss marking features at the edges of subject images. We had to cut up the HiRISE images into smaller chunks in order to get the resolution needed and make the Planet Four website as easy to use as possible.
Each color in the plot below represents a Planet Four subject image. The dashed blue lines are to show the overlap region boundaries and the solid blue lines are the boundaries between the subject images.
These are all from Ithaca where the fans tend to be very wide. It’s a very flat region on the Martian South Polar region, which might have something to do with it. So it’s one of our best cases to look at what we should do about combining the sources from different subjects in the overlap region.
Looking at these plots, we see fan directions aren’t impacted. That although in some cases we have to fans or two blotches on top of each other with different widths and extents, the direction of the source is well represented. By using shapely we’ll be able to deal with this. For the project’s first paper, we’re focused on wind directions so we’re calling the catalog done for now and will do the Shapely stage next for fan and blotch areas and counts.
We can now confidently turn your clicks into wind directions. This is a big milestone for the project. It means we get on to writing the second half of the Planet Four paper, talking about the catalog and what we see for wind directions. Onwards and upwards!
I thought I’d share a figure from last week’s science team call that the science team discussed. Michael was looking at combining clustered features with Shapely, a Python package for manipulation and analysis of planar geometric objects. Partly this is to investigate whether this could be used to deal with differing clusters in the overlap regions between neighboring subject images and also test out if we can use the software package to easily calculate the total area covered by the seasonal fans and blotches. Shapely does a good job of merging the blotches together as you can see from the figure below. This definitely looks like a way forward for calculating the total surface area per time of year covered in dark fan material.
We’re now working on dealing with the last major component of the Planet Four data processing pipeline, the overlap regions of neighboring subject images. We divide each HiRISE images into many smaller 840×648 pixel subimages or subjects that we show on Planet Four. To make sure we capture fans and blotches that are the edges of our subject images, we have a 100 pixel overlap between the neighboring left and bottom subject images. This means that we have duplicate markings that cover the same source which we need to identify as being the same source to allow for counting the number of seasonal sources and to also accurately measure the shape of very large fans or blotches.
We spent part of the last science call looking at some examples of overlap regions and the outputting fan and blotch shapes after clustering to decide what to do.
If you focus on the center sources in the two plots above, you see there are lots of markings identifying the same shape from the different subject images that contained varying parts of the central blotch or fan. Based on what we see, we think we if in the overlap region we only keep the largest source and anything that extends beyond that we will accurate identify the fan or blotch being marked. We’re going to test that this week and review the output from the catalog for a small portion of the overlap regions to confirm.
Once we sort what to do in the overlap regions, the focus should be writing all of the steps in the processing pipeline into the paper draft.
I’m pleased to announce that our first scientific paper for Planet Four: Terrains was accepted to the journal Icarus. Below is a snapshot from the top of the paper manuscript, and the paper is publicly available via the free preprint we’ve put online here.
A big thank you to all the volunteers who contributed to the publication. We acknowledge everyone who contributed to the project on the results page of the Planet Four at: http://p4tauthors.planetfour.org
The paper presents the first spider and swiss cheese terrain catalog derived from your classifications. 90 CTX images comprising ~11% of the Martian South Polar region southward of -75 N latitude were searched by Planet Four: Terrains volunteers. This comprised approximately 20,000 subject images reviewed on the Planet Four: Terrains website with 20 independent reviews. The P4: Terrains search coverage is shown below:
Applying a weighting scheme, we combine classifications together to identify spiders and swiss cheese terrain. The weighting scheme isn’t testing anyone, but it helps us find more spiders by allowing us to pay slightly more attention to those that are better at identifying spiders and help increase the overall detection efficiency of the project. Details can be found in the paper.
Using the weighting scheme each Planet Four: Terrains subject has a spider score which is the sum of the weights of the volunteers who identified spiders in the image divided by the sum of the weights of the volunteers who reviewed the subject image. Using classifications from Anya and I for a very small subset of the subject images, we found a spider scores above which we’re highly confident the identifications have few false positives.
To our surprise when we compared to the map of the secure spider locations to the geologic map of the South Polar region, we found araneiforms or spiders where we didn’t expect them to be. In previous surveys of the South Polar region, araneiforms were found to be located only on the South Polar Layered deposits (SPLD). The SPLD has been measured to have a height of ~4 km and covering a surface area of ~90,000 square kilometers mainly comprised of varying dust and water ice layers as well as some buried carbon dioxide and water ice deposits. Previous works have theorized that something about the unconglomerated nature of the SPLD, might make it easier for spiders to form there than other areas of the South Polar region
To confirm these identifications were real, we needed HiRISE imaging. CTX has a resolution of 6-8 m/pixel. HiRISE can resolve up to a coffee table on Mars with a resolving power of 30 cm/pixel. With HiRISE we could see the wiggly dendritic nature of the channels and as well see seasonal fans to confirm that these form via the carbon dioxide jet process. 8 areas outside of the SPLD were targeted last Summer and Fall by HiRISE.
Below are just a few examples of the HiRISE subframes of these regions off the SPLD:
There be spiders! Araneiform channels can clearly be seen in the images above. The HiRiSE images confirm the spider/araneiform identification. We also see seasonal fan activity as well. For the first time we have found spiders/araneiforms outside of the SPLD!
This result is exciting. For some of these areas we have sequences with HiRISE taken over time which we hope we can put it into Planet Four to measure how the fans sizes and appearance are different from their counterparts on the SPLD. Now we get a chance to study how these locales off the SPLD are similar or differ from the SPLD and try to learn why these areas and not others have spider channels.
We’ve only searched a small fraction of the Martian South Polar region. We have more images on the site to expand the search area to see where else spiders/araneiforms may be. Help us today by classifying an image or two at http://terrains.planetfour.org