I’ve been learning to use JMARS (Java Mission-planning and Analysis for Remote Sensing) to plot the coverage of the CTX images for Planet Four: Terrains. JMARS is a really nice tool for overlaying observation footprints and different maps and datasets on top of each other for Mars and other planets.
I decided to take a look at what the HiRISE Season 2 and Season 3 observations, that the science team is currently working on writing up, look like on a map of the South Pole when you plot their physical coverage on the pole . You can really see the overlap and what a small area that HiRISE covers compared to CTX.
Here’s the footprint HiRISE observations for Seasons 2 and 3 outlined in red on the elevation and topography map of the Martian south pole (latitude and longitude lines are in 10 degree intervals).
Here’s a zoom in on one of our favorite regions, Inca City. You can really see the repeat coverage outlined in white in this case.
Here’s another zoom in of a different area, where you can see multiple seasonal targets outlined in red:
For comparison here’s the footprints of the first set CTX images (latitude and longitude lines are in 10 degree intervals). The colors represent geologic units, but for this comparison we’re focusing on spatial distribution and coverage.
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.
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 http://terrains.planetfour.org
I want to talk why we created the new project Planet Four: Terrains if we have Planet Four already.
The very high resolution images of HiRISE camera are really impressive and one might think that there is no reason to use a camera with lower resolution anymore. Wrong!
First, high resolution of HiRISE image means large data volume. To store on-board and to download large data from MRO spacecraft to Earth is slow (and expensive) and this means we are always limited in the number of images HiRISE can take. We will never cover the whole surface of Mars with the best HiRISE images. Sadly. so we use different cameras for it. Some – with very rough resolution and some – intermediate, like context camera (CTX). We can use CTX, for example, to gain statistics on how often one or the other terrain type appears in the polar areas. This is one point why Planet Four: Terrains is important.
Second, because HiRISE is used for targeted observations, we need to know where to point it! And we better find interesting locations to study. We can not say “let’s just image every location in the polar regions!” not only for the reason 1 above, but also because we work in a team of scientists and each of them has own interests and surely would like his/her targets to be imaged as well. We should be able to prove to our colleagues that the locations we choose are truly interesting. To show a low-resolution image and point to an unresolved interesting terrain is one of the best ways to do that. And then, when we get to see more details we will see if it is an active area and if we need to monitor it during different seasons.
Help us classify terrains visible in CTX images with Planet Four: Terrains at http://terrains.planetfour.org
I thought I’d go into a bit more into detail about what exactly you’re seeing when you review and classify an image on Planet Four. On the main classification site we show you images from the HIRISE camera, the highest resolution camera ever sent to another planet. Looking down from the Mars Reconnaissance Orbiter, HiRISE is extremely powerful. It can resolve down to the size of a small card table on the surface of Mars. The camera is a push-broom style where it uses the motion of the spacecraft it is hitching a ride on to take the image. During the HiRISE exposure, MRO moves 3 km/s along in its pole-to-pole orbit , which creates the length of the image such that you get long skinny image in the direction of MRO’s orbit. The camera can be tilted to the surface as well, which can enable stereo imaging.
The HiRISE images are too big to show the full high resolution version in a web browser at full size. The classification interface wouldn’t quickly load, as these files are on the order of ~300 Mb! – way too big to email. But the other reason is that the full extent of a HiRISE full frame image is too big and zoomed-out for a human being to review and accurately see all the fan and blotches let alone map them. So to make it easier to see the surface detail and the sizes of the fans and blotches, we divide the full frame images into bite-sized 840 x 648 pixel subimages that we call tiles.
For the Season 2 and Season 3 monitoring campaign, a typical HiRISE image is associated with 36-635 tiles When you classify on the site, you’re mapping the fans and blotches in a tile. Each tile is reviewed by 30 or more independent volunteers, and we combine the classifications to identify the seasonal fans and blotches. To give some scale, for typical configurations of the HiRISE camera, a tile is approximately 321.4 m long and 416.6 m wide. The tiles are constructed so that that they overlap with their neighbors. A tile shares 100 pixels overlap in width and height with the right and bottom neighboring tiles. This makes sure we don’t miss anything in the seams between tiles .
If you ever want to see the full frame HiRISE image for a tile you classified, favorited, or just stumbled upon on Talk, there’s an easy way to do it. On the Talk page for each tile we have a link below the image called ‘View HiRISE image’ which will take you to the HiRISE team public webpage for the observation, which includes links to the full frame image we use to make tiles plus more (note= we use the color non-map projected image on Planet Four). Try out this example on Talk.
So next time you classify an image and recall how detailed it is, remember that although it’s just a small portion of the observation, your classifications are hugely important. Without them we wouldn’t be able to study and understand everything that’s happening in the HiRISE observations. It’s only with the time and energy of the Planet Four volunteer community that we are able to map at such small scales and individually identify the fans and blotches., which is crucial for the project’s science goals. So thank you for clicks!
On Christmas Day 2003, the British lander Beagle 2 entered Mars’ atmosphere and was never heard from again. It had hitchhiked a ride off of ESA’s Mars Express orbiter. The lander successfully departed Mars Express and then nothing. Mars is hard, and many a spacecraft has ended in demise trying to orbit around or land on the red planet. Beagle 2 never phoned home. Its fate was unknown.
This is before the arrival of Mars Reconnaissance Orbiter (MRO) and its high resolution HiRISE camera. MRO entered orbit in 2006 and is the highest resolution imager sent to a planet in our Solar System. Now a days it is used to capture the descent of Phoenix lander and Curiosity rover (which is a challenging feat in itself), but that information gives a glimpse of what was going on if something goes awry in those 7 minutes of terror of landing, entry and descent. Later it can be used to to spot the lander on the surface. But the only image of Beagle2 at the time of its’ landing attempt is the separation image from it’s mothership Mars Express.
For 12 years it’s fate wasn’t known. HiRISE can resolve objects down to the size of a small card table on Mars’ surface. The predicted landing ellipse for Beagle 2 was imaged by HiRISE and scientists scoured the images looking for something in essence not red. They looked for something bright and shiny in the images that could be Beagle 2. And they succeed. A few days ago, ESA and NASA announced that the Beagle 2 and its used parachute had been found.
The British lander wasn’t found in pieces scattered across the surface. It was intact. It had successfully landed on the surface. A huge accomplishment and success for the United Kingdom. They stuck the landing but the deployment had some hitch preventing Beagle 2 from communicating with Earth.With HiRISE’s resolution, the images reveal the rough outline of the lander. Beagle 2 had a petal design. All the petals had to deploy for the communications antenna to be exposed and able to send/receive signals. It appears that Beagle 2 only partially deployed (a broken cable, an air bag that didn’t inflate or deflate, a rock underneath could be one of the multitude of reasons that could have prevented the final panels from unfurling), with that vital communications antenna blocked it ended the mission.
We now know what happened to Beagle 2 that Christmas Day back at 2003. Learning the British spacecraft landed successfully will help engineer future European Mars missions. I also think the ending to this detective story serves as a reminder for how powerful the HiRISE camera is. Of the imagers aboard spacecraft orbiting Mars now and in the past, HiRISE is the only instrument capable of spotting Beagle 2. It’s with its keen eyes that it resolves the hundreds of thousands of fans dotting the South Pole of Mars that we ask for your help to map at http://www.planetfour.org
Season’s Greetings. From all of the Planet Four team to all of you on Earth and Mars, we wish you a very merry Earth solstice, Happy Holidays, and a very happy new Earth Year.
Another holiday treat released by the HiRISE team this December was a 3-D image or anaglyph of Manhattan taken in November. You can find the full image here.
If you throw your red and blue 3-D glasses on, you should see the troughs of the spiders channels with fans dotting the surface. With these observations planetary scientists can measure depths of the channels and slopes of terrain. These images are created by combining two images of the same location (called a stereo pair) where HiRISE was oriented at different angles to the surface. You can read about the details here.
And if you’re looking for a cocktail for your new year’s party – check out this year’s Zooniverse cocktail list including a Planet Four themed drink (the last door of the Zooniverse’s advent calendar)
Adding more red (planet) to this holiday season, another new HiRISE image of Inca City was publicly released by the HiRISE team this month. This is the 6th image from the sequence taken this fall as part of Season 5 of the seasonal monitoring campaign (We’re currently showing images from Season 4 on Planet Four). The image sequence was released as part of the public vote we organized with the help from our friends on the HiRISE team. You can find the rest of the sequence here.
The HiRISE camera right has been taking observations looking for activity on the Martian South Pole over the past few months as part of the new monitoring season (Season 5). In August, we partnered with the HiRISE team for a public vote to determine which polar region would have its first observation prepared for public release. The region dubbed ‘Inca City’ won. We have a big surprise. Not just one image, but all currently available observations this season of Inca City were publicly released by the HiRISE team. That’s right 5 brand new images of Inca City were recently released! You can find these images at:
- Spring in Inca City I
- Spring in Inca City II
- Spring in Inca City III
- Spring in Inca City IV
- Spring in Inca City V
(If you’re looking to make your computer more Planet Four-themed, each of the links above have versions of the images formatted to be computer desktop backgrounds.)
Today, we have a post by Planet Four Principal Investigator Candy Hansen telling tell you more about these observations:
It is southern spring again, and once again we are taking images of our favorite locations. We return to the same sites so that we can study processes from year-to-year. Do spring processes always play out similarly? Or do the occasional dust storms affect when fans appear and the pace of seasonal activities?
This location is known informally as Inca City. As citizens of Planet Four you already know that a seasonal polar cap composed of CO2 ice (dry ice) forms every winter. In the spring the ice sublimates from the top and the bottom of this layer of ice, and under the ice the trapped gas builds up pressure. Eventually a weak spot in the ice ruptures, and the gas escapes, carrying material from the surface with it. The material is deposited on the top surface of the ice, forming the fans and blotches that you have been measuring.
Inca City has distinctive ridges, one of which is shown at the top of this series of cutouts. The first cutout on the left was the first image to be taken after the sun rose, marking the end to polar night. We label time on Mars by “Ls”, which indicates the position of Mars in its orbit. Spring officially starts on Ls = 180, so at Ls = 174 there is very little sunlight. In spite of the small amount of sunlight seasonal activity has already started, and fans can be seen emerging from “spiders”, known formally as “araneiforms”.
These images have not been map-projected yet, so use the black arrow pointing at one of the spiders to orient the same locations from image to image. In the second image from the left, taken about 2 weeks later, you can see that the fan from that spider has become more prominent. In the araneiforms above so much dust has blown out that the individual fans seen in the leftmost image have begun to merge. The ridge is peppered with small spots where the seasonal ice has ruptured (blue arrow). Near the bottom of the second image there are new fans associated with boulders. Below that, at the bottom of the image, four new rupture sites have fans going in multiple directions.
The differences between the second and third images from the left are not substantial. That is because the time difference between the two is just 6 days, or “sols”. Fans on the ridge have lengthened just a bit, possibly due to fine material sliding downslope. In the fourth image from the left, taken at Ls = 191, the fans covering the araneiforms and on the ridge slope appear grey – are fine particles sinking into the ice? At the bottom of the image distinctive bright bluish fans are apparent.
Look at the boxed area in the 5th image and compare it to that same area in the 4th image, just below the indicated spider. The bland surface in the 4th image is now cracked. Polygonal cracks typically occur at this time in the spring. There are no easily-ruptured weak spots, so the pressure of the gas below the ice simply cracks the large plate of ice. The ice must have thinned to the point at which this pressure can break the ice sheet. Once it has cracked the gas escapes and new fans emerge, aligned along the cracks.
The ice has continued to thin by the time of the 6th image, and the araneiforms have likely defrosted entirely. More small fans emerge from cracks in the ice.
The image above taken by HiRISE isn’t of the South Pole of Mars or any region on Mars for that matter. It’s an interloper from the Oort cloud (reservoir of the long period comets) coming in for a close encounter to Mars on its way into the inner Solar System for its closet approach to the Sun. This icy planetesimal originated in the Oort cloud and was perturbed onto an orbit that has slowly brought it into the inner Solar System and on a path that brings the comet close to Mars. So close in fact (87,000 miles away from Mars) that this is closer than any comet has come to Earth since the dawn of modern astronomy. This provided a rare opportunity to study this icy remnant of planet formation up close and personal with the flotilla of spacecraft orbiting Mars.
HiRISE, is the highest resolution camera sent to to the Red Planet, and the images you see on Planet Four come from it. HiRISE is designed to taken observations staring below at Mars. It’s a push broom camera so it’s using the motion of the spacecraft (Mars Reconnaissance Orbiter, MRO) its aboard to create the image. To observe a comet requires a whole different way of observing using MRO to point and slew to target the comet. This was no easy feat but the HiRISE team accomplished it, taking images of the comet several days before and shortly before cloest encounter. During the closest part MRO was behind Mars to shield it and its instruments (including HiRISE) from the large amounts of dust entering the Martian atmosphere and could possibly damage or destroy the onboard instruments. This is likely the best optical image of Comet C/2013 A1 Siding Spring, we’ll have. It may look blurry and span only a few pixels, but observations like this will significantly constrain the size of the nucleus. Congratulations to everyone involved for making these challenging observations successful.
This is the only the second comet imaged by HiRISE. HiRISE has tried this previously observing Comet ISON, a sun-grazing comet that broke up shortly before or during its encounter with the Sun. HiRISE imaged ISON’s nucleus and was able to put the best size constraints on the comet (better than the limits from the Hubble Space Telescope), that placed it around 1 km or smaller. With that size, ISON would be predicted not to survive matching the observations. The cool thing about both Siding Spring and ISON is that these comets were discovered with at least a year’s notice before their closest approach giving astronomers and planetary scientists time to apply for telescope time and mobilize resources (including spacecraft orbiting Mars!) to observe these elusive objects.
You can read more about these HiRISE observations here and here. If you’re interested in hearing more about observations like this get undertaken by HiRISE and the team behind the camera check out this Planet Four Live Chat where we had discussing the preparations for the Comet ISON imaging with Kristin Block and Christian Schaller. For a summary of all the Comet Siding Spring observations taken by the spacecraft orbiting Mars check out this blog by the Planetary Society’s Emily Lakdawalla.