This was originally posted here, written for the IAG Planetary Geomorphology Working Group’s featured image of the month. The author, Kathryn Fishbaugh, is a HiRISE team member, and she allowed us to post a copy of it here as well. It’s great to see the results scientists are getting from HiRISE images – and you thought they were just pretty pictures!

At the north pole of Mars lies Planum Boreum, a dome of layered, icy materials similar in some ways to the large ice caps in Greenland and Antarctica and comparable in size to the former. The dome itself consists of the polar layered deposits, consisting of over 90% ice with a little bit of dust, and the basal unit, consisting of ice, dust, and sand.

The image shows a cliff in the Polar Cap deposits. The upper portion of the cliff consists, for the most part, of fractured portions of the polar layered deposits and has a reddish appearance due to dust both coating and entrained within the ice (red arrow). Below that is the basal unit, with more flat-lying layers of blueish material that is basaltic sand (blue arrow) (like the black sand beaches in Hawaii). You might also notice some lighter colored layers. Those are also fractured and composed of ice and dust, like the polar layers above them. And at the bottom of the image, sand eroding from the basal unit is collecting into dunes (white arrow). The entire cliff is about 700 m (2300 ft.) tall (comparable to the depth of the Grand Canyon).

Scientists study past climates and trends in global warming on Earth by examining the air bubbles trapped within ice cores (long, cylindrical samples of ice, extracted with a drill) taken from Greenland and Antarctica. These ice cores contain ice created from last year’s snowfall to many hundreds of thousands of years ago and have trapped bubbles with the same atmospheric composition as existed when the snow fell. From this composition, scientists can figure out what was the contemporary temperature and hence how the climate has changed over time. Similarly, the ice in the polar layers and basal unit on Mars must also have recorded how the martian climate has changed. (more…)

Today a press release went out about a forthcoming paper in the journal Geology (click here for full text online or here to download a PDF). John Grant, a Co-Investigator on the HiRISE science team, is the lead author, and most of the co-authors are also on our science team.

What is a megabreccia? A breccia is a jumbled-up mixture of broken rocks, cemented together by a finer-grained material. We see them in impact craters and volcanoes on the Earth, places where there was a lot of violent energy to break up rocks. A megabreccia is just a larger version of that – something we can see with HiRISE resolution, as opposed to something you’d have to pick up in your hand to identify. The megabreccia in Holden formed when the explosion that opened the crater shattered rocks, mixed them up, and then the fragmented ejecta collapsed back down into the crater. Before HiRISE, we didn’t have the resolution to detect these textures.

This is a cutout of an image taken in Holden Crater, showing the megabreccia texture, in false color as usual. A context map is shown to the right, showing where in the crater rim this image is located (click these images to enlarge). The blocks here are mostly darker, and they’re embedded in a lighter-toned material. The dark chunks are kind of “scooped out,” which means they’re more easily eroded than the surrounding light-colored rock. Scientists think this may be because they’re sedimentary rocks, formed at the bottom of a lake or river. The stripey dark blobs on top are sand dunes that are slowly covering up the area again.

This megabreccia is located in an area scientists find fascinating for other reasons, too: there are clays that were laid down over a long period of time when it had to be wet. This implies there was once a lake in this crater – perhaps more than once over its history. At one point, the lake broke through the rim of the crater, releasing a huge flood of liquid water. You can see the channel this formed in the context map above. This flood eroded away material that was covering the megabreccia, exposing it for HiRISE to see.

The HiRISE image PSP_003077_1530 shows another part of Holden Crater, and the caption includes more information about the geologic history of the area.

Three HiRISE papers are coming out in a special issue of the journal Science today. Our science team has been working hard on analyzing the images we take, and they’ve discovered some interesting things.

One paper talks about a few aspects of the history of water on Mars: HiRISE images of “rock glaciers” and bright deposits in gullies that might be extremely recent. HiRISE observations of an area called Athabasca Valles were used to show that it is actually covered with a thin veneer of lava. A third paper discusses thin layers in the North Polar cap. HiRISE is able to discern very fine layering (seen in an excerpt of image PSP_001636_2760 at left), as well as the color and thickness of each layer. Since these layers were laid down over hundreds of thousands of years of Martian history, they provide a record of climate change on the planet.

You can find a lot of things on the HiRISE website that are impossible to include in a print journal – like full-resolution color versions of the images from the papers, and (my favorite) cool 3-D flyover movies of the stereo observations. Our webmaster designed this lovely page for accessing these special products. Have fun flying over Mars!

My new temporary daily routine here at HiRISE Operations:

1. Validate the image data that have arrived since last time I checked. Are the raw image files we receive gap-free and are the file sizes as expected? Did the Uplink team command the HiRISE camera properly? So far, they have a perfect record!
2. Keep checking to see if new data is arriving for processing.
3. Are our automated processes running properly?
4. Is the data being stored correctly and can the team access the images in the appropriate places?
5. Finally! Actually look at the new images. In between “oohs” and “ahhs” check to see that the images look good. Did our automated software handle the data correctly? Do I need to do any manual reprocessing of image data?
6. Report my findings to the team via email.
7. Get up and see what the scientists and other team members are up to.
8. Eat some Cheetos.
9. Repeat as necessary.
10. A million other tasks.
    

By the end of the day I am covered in Cheeto dust (joking) and amazed by some new vista of Mars (seriously).

What is it we find so amazing? I can only speak for myself, but in observation TRA_000823_1720, the boulders lying about casting shadows indicate just how “Hi” resolution the HiRISE camera can go. In the second observation – TRA_000825_2665 – the stack of water ice and dust layers and the patches of water frost make for a distinctive landscape. At this resolution, there is a marked difference between the north polar region on Mars and the pictures I have seen of the Earth’s own polar regions.

To me, this is the great joy of planetary science: seeing new vistas that are at once familiar and unfamiliar, and never, ever routine.

The second image has been released in its full-scale version.