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HiRISE Targets

We started Planet Four: Terrains with the main goal of finding new regions to study during the upcoming seasonal processes HiRISE campaign. The idea was to have people scour low resolution Context Camera (CTX) images for terrains indicative of sculpting during the seasonal processes  produced by never-ending cycle of  carbon dioxide ice being deposited on the surface in the winter and that ice sublimating in the spring and summer. We would then  select a portion of those areas for further study with high-resolution imaging with HIRISE. With the varied textures of the Martian surface it would be difficult for a machine to do this task, but the human brain is well suited to this task.

We launched Planet Four: Terrains at the end of June as part of the launch of the Zooniverse’s new citizen science platform and project builder portal. Planet Four: Terrains had little less than a year to review 90 full frame CTX images divided into 20,122 subimages or subjects as their known on the website. With your help, the project was able to get through all 20,122 subjects in time, and even put in more images. Thanks to your classifications and Talk discussions, the science team was able to come up with a list of images and locations for further study. We aim to have the HiRSE camera point at these locations and snap images. Some of these locations will be monitored throughout the Southern spring and summer. Right now these locations have been entered in the HiRISE target database. This means that Planet Four: Terrains has successfully achieved one of its prime goals!


One of the new targets of interest found by Planet Four: Terrains that will monitored by HiRISE during the spring and summer on the south pole of Mars starting in the coming months. This subject was classified as part of the second set of CTX images classified on Planet Four: Terrains  Discovery details

Now, Candy Hansen, PI of the project and head of the seasonal processes campaign with HiRISE, will prioritize our  targets with the rest of the regions that the HiRISE team wants to study. The first of these should with any luck get images in the next few months. We’ll keep you updated here on the blog.The final  list of targets from Planet Four: Terrains is  a mix of locations found on Talk and through the classification interface.  We’ll have more details as we get closer to the start of Southern spring (July 5th), but we wanted to share one of the new locales,spotted thanks to the volunteer contributions on Planet Four: Terrains, that will be imaged by HiRISE. This specific region shown above was highlighted on Talk.  It was noticed by the science team, and  we agree it is an interesting area to look at how spiders develop. We’re interested to see how the seasonal fans and blotches over the coming Martian Southern spring and summer. We’re currently planning a sequence of images at this location. CTX has a resolution of 6-8 meters per pixel. HiRISE has a resolution of 30 centimeters per pixel, so we’ll get to see a lot more detail particularly in the structure of the spider channels than what’s current visible in the CTX image above.

This isn’t the end of the project, we’re really just getting stared.  Because of your classifications, we’ve found spiders in interesting and potentially unexpected regions so we’ve decided to keep the project going with new locations to review. Help today at

More Examples of Baby Spiders

I’ve been looking at the results of my pipeline to combine the many classifications we get for each Planet Four: Terrains subject (CTX subimage) and also the subjects you’ve marked with Talk hashtags in preparation for picking a list of final targets for the HiRISE seasonal campaign. I thought I would share with you some great examples of images with baby spiders that I  found. If you’re having a hard time identifying spiders from baby spiders or a channel network, here’s some advice from our site guide:

  • Legs longer than the size of the center pit: It’s a spider
  • Only a pit or has tiny legs shorter than the size of the center pit: It’s a baby spider
  • No discernible pit and no centralized pattern but more grid or network like: It is a channel network

Gallery of Subjects With Baby Spiders – click an image below to get the slide show – Enjoy!


WeMartians Interview: Citizen Science on Mars

WeMartians is a brand new podcast aimed to engage the public in the exploration of Mars. The latest episode is about citizen science on Mars with  Michael talking about Planet Four and Planet Four: Terrains.  Listen to Michael (and cameos of other familiar Zooniverse voices) below or on the WeMartians website.

Countdown to Picking New Proposed HiRISE Targets

One of the key goals of Planet Four: Terrains is to identify new areas of interest to observe with HiRISE during the seasonal processes campaign so that we better learn about the carbon dioxide geyser process and about how and were spiders and related channels form. You can read more about the particular goals of Planet Four: Terrains here. Over the months we’ve read the discussions and comments on Talk and been making a list of regions to consider from your observations. We’re really intrigued by many of the things you’ve all spotted. Which is fantastic news! Talk has been a huge asset for this work, but we’re also using the classifications from the classification interface as well. I’ve spent the past three weeks putting together a software pipeline to take the multiple classifications per CTX subframe (typically 20 people review each subject image) to identify spiders, baby spiders, channel networks, craters, and the Swiss Cheese Terrain.

Now that the machinery is all together combined with the interesting gems on Talk we’re ready to make our list of proposed new HiRISE monitoring targets. By April 20th I aim t provide the rest of the Planet Four: Terrains science team a compiled list of locations for them to review. Then Anya will input these into the HiRISE planning system where they will be considered with the HiRSE team’s science goals and eventually Candy who wears many hats including Deputy Director of the HiRISE camera and lead of the seasonal processes campaign will prioritize these new areas with the already existing targets in the seasonal processes observing program. We aim to be ready for HiRISE’s first attempt to image the South Pole which is coming up in about 60 days or so.

This is where you come in. We have new images of different areas on the site now. There have already been some interesting images from this set I’ve forwarded to the rest of the team after seeing discussions on Talk. Let’s make a push to classify as much of the new data set as possible before the 18th of April. The more subjects reviewed the greater chance to include those areas at the start of the monitoring campaign. Not to worry though, we’ll also have a few chances to include additional targets later in  the Spring Season to the HiRISE monitoring campaign if need be or to the next one.

If you have a free moment, classify an image or two at


Brand New Images on Planet Four: Terrains

We’ve been finding interesting regions thanks to your classifications and your Planet Four: Terrains Talk comments. We’ll soon be start preparing for the upcoming HiRISE seasonal monitoring campaign and selecting our final list of new targets for HiRISE. The Sun will be fully above the horizon of the  Martian South Pole and conditions will be favorable for imaging sometime around July, so we need to get started very soon.  The excellent news is that  thanks to your help, we’ve completed the original set of CTX images that we had planned for the project. Here’s where on the coverage of the  CTX images that we selected and you’ve been classifying since June.

CTX coverage with MOLA elevation map (Courtesy of JMARS )

CTX (Context Camera) image coverage in cyan with MOLA elevation map (Red is higher elevation) (Courtesy of JMARS )

The even more exciting news is that we’re extending the project and have uploaded a new set of CTX images to the website! Looking at the preliminary analysis of your classifications, we’re seeing interesting patterns in the distributions of spiders, baby spiders, and swiss cheese terrain. We want to investigate this further by covering more of the South Pole that we hadn’t looked at already. These CTX  images have never before been looked at by human eyes in such detail before. There are bound to be something interesting, and if so we will still have time to add the region to our HiRISE target list.

Here’s a comparison of the location of the new CTX  images in dark blue compared to the our first set of observations on the reviewed on the site in cyan.

CTX coverage with MOLA elevation map (Courtesy of JMARS ) Blue = coverage of new images just uploaded Cyan = locations of previous images classified

CTX coverage with MOLA elevation map (Courtesy of JMARS ) Blue = coverage of new images just uploaded Cyan = locations of previous images classified

Help search the new CTX  images or spiders, swiss cheese terrain, and more by classifying an image or two at

Craters on the Martian South Polar Deposits

Today we have a guest post from Margaret Landis.  Margaret  is a third year PhD student at the University of Arizona’s Lunar and Planetary Laboratory, where she studies impacts and frost transport on Mars

 CTX image B08_012814_0962_XN_83S173W of a portion of the South Polar Layered Deposits - Image Credit:NASA/JPL-Caltech/Malin Space Science

CTX image B08_012814_0962_XN_83S173W of a portion of the South Polar Layered Deposits – Image Credit:NASA/JPL-Caltech/Malin Space Science

Impacts, from asteroids and comets, occur on every solid surface in the solar system. When a space rock hits a planet, it leaves behind an explosion crater depending on how large the space rock was and how strong the target material is. How we study and count these tells us an incredible amount about the history and composition of the surface: this is one of the reasons why I’m excited about Planet Four: Terrains’ Mars south polar crater tagging!

First of all, craters expose the layers underneath the surface of a planet. Just look at terraced craters on Mars. Of course material can also fill in craters, which means craters are interesting laboratories for exploring the material a planet is made out of.

Second, and what I am primarily interested in for Mars, is that craters can act like a clock for the age of a surface. The number and size of craters on a surface is primarily determined by the types of impactors that are hitting the planet, and we can find this out in a couple of ways. One is looking at the number of asteroids of a particular size which we can do using telescopes, and another is looking at the number of craters that form per a particular period of time. The next step is to find the period of time a certain number of impacts happened over. For the Moon, this is relatively straightforward because there are samples of the rocks returned from the Apollo missions. Using laboratory techniques, geochemists can get an age for the rock. This is a reference point: a certain number of craters on a surface is a given age from the age of a rock returned from the lunar surface. When this is translated to Mars, this becomes much easier said than done.

In essence, if the size of craters is measured and the number of craters at each size are counted up, that can be translated to the number of space rocks that have hit the surface. If we know the rate at which that occurs, we know how old the surface is.

Why do we care about figuring out how old a surface is? For the north and south polar deposits on Mars, they are made mostly of water and carbon dioxide ices. These are powerful greenhouse gasses and could make up a large amount of a possible martian atmosphere. When and where these ices are on the surface tells us more about where and when the martian atmosphere could have gone, as well as Mars’ climate in the recent past.

For example, the polar layered deposits (PLD) are layers of different thickness and dust content, two things that are controlled by the local climate at the time that layer formed. We can measure the relative thinnesses of the layers and get some ideas about how long they took to form. These are similar to ice cores from the Earth, collecting information about what was in the air at certain times. However, unlike using ice cores on the Earth where we can measure the radioactive isotopes trapped within the dust in the ice and determine how old a certain layer is, we don’t have that capability for doing that on other planets yet. So, how can we get an age at a point in the south PLD (SPLD) stack of layers? From the crater age dating!

The residual ice cap is generally considered the layer of the SPLD forming at present day. Using craters, we can come up with an age of the surface.

Once again, this sounds simple but is much more complicated. One of the complicating factors is that the large surface area of the uppermost layer of the SPLD (the southern residual ice cap), and all of it has to be looked over for craters. Another thing that makes the south pole more complicated is that the exotic behavior of the carbon dioxide ice (like “spiders”, geysers, and pit formation) makes for sometimes circular features that are not impact craters, or can quickly hide the tell-tale signs of craters. The longer craters have been sitting out in the erosive environment of Mars, and the softer the rim appears and the flatter the floors become. These old craters can also be covered by other features, too. This is the perfect example of a task that one person could do, but it would take a long time.

This is where citizen science comes in: there are 90,000 km^2 on the surface of the south polar deposits! With lots of people looking over lots of images, the cataloging of craters becomes much faster and straightforward. This means that the crater counts go more quickly and accurately, which fits into figuring out the surface age and recent geologic history of the south polar deposits.

With all the images tagged as containing craters, I’ll build a crater database in order to enter Mars Reconnaissance Orbiter’s High Resolution Imaging Science Experiment (HiRISE) suggestions to get more detailed images of each of the craters in order to mark their location and measure their diameter. South polar summer happens later this year, and I’ll be sure to write an update on the project’s progress!

Planet Four at the 47th Lunar and Planetary Science Conference

The abstracts for the accepted posters and talks at the 47th Lunar and Planetary Science Conference (LPSC) are now posted online. At the meeting in March, Planet Four and Planet Four: Terrains will be well represented at the Woodlands, Texas. Michael and Candy will be there with two posters presenting results thanks to your time and your clicks.

You can read Michael’s Planet Four poster abstract here and Candy’s poster abstract on Planet Four: Terrains here. The Planet Four: Terrains abstract contains examples of areas of interest found thanks to volunteers on Talk posting about what they’ve seen on Talk. Thanks especially to Ray Perry, Andy Martin, and Bill Wagner for their help spotting some interesting images that were included in the abstract.

New images on Planet Four: Terrains

Image Credit: Planet Four tile derived from a CTX image - NASA/JPL-Caltech/Malin Space Science Systems

Image Credit: Planet Four tile derived from a CTX image – NASA/JPL-Caltech/Malin Space Science Systems

We’ve uploaded a new batch of CTX  data onto Planet Four: Terrains. These new images have never been reviewed by human eyes in such detail before. With your help, Planet Four: Terrains aims to map where different types of Martian terrains occur in images taken of the South Pole  by the Context Camera aboard Mars Reconnaissance Orbiter. We will use the locations you identify to find new areas of interest to serve as targets for detailed study with the HiRISE camera, the highest resolution camera ever sent to a planet! These high resolution images in turn will end up on the original Planet Four to study the fan and blotch cycle in these new areas.

Who knows what interesting finds might be waiting in these new images. Explore the South Pole of the Red Planet today and help identify terrains at

What are the pancakes in depressions?

You might have images like those below while classifying on Planet Four Terrains.







Some people on Talk have started labeling them #pancakesindepressions . I didn’t know what was causing this terrain, so I showed these to the rest of the Planet Four: Terrains team. They think this this is a variation on the same processes that create the swiss cheese terrain. That the sediment layers have varying amounts of ice that get eroded at different rates, creating then layered surface.

I’ve post an example of the swiss cheese terrain below for reference:


Example of swiss cheese terrain

The swiss cheese terrain (see above picture), is compromised of a series of small edged pits that are caused by the uneven deposition and sublimation of carbon dioxide ice. The pancakes in depressions are a separate feature, so they shouldn’t be marked as swiss cheese terrain in the main classification interface, but if you see more images like the examples above, do mark them on talk with #pancakesindepressions

6 months of Planet Four: Terrains – Top 20 favorites of 2015

Today marks 6 months of Planet Four: Terrains. We thought we’d share the 20th most  favorited  images since launch. You can view the images below or check them out on in this collection.

Click any of the images below and then you use left and right arrow keys to peruse the whole set.

Wishing you a fantastic end to 2015 and great start to 2016!