Howdy, readers. About every two years, the orbits of Mars and Earth work to put Mars behind the Sun when viewed from Earth. In this arrangement, the Sun makes it pretty tough to communicate with the various spacecraft we’ve got orbiting the Red Planet and creeping around on its surface. This arrangement, called “solar conjunction,” lasts for about five weeks. During this time, we generally reduce operations to the bare minimum required to keep these marvels running. MRO’s HiRISE is no exception, do we haven’t been taking images for the past five weeks.

That ends today, though. Mars recently came out of solar conjunction and operations have been ramping up. We ought to be starting our first post-conjunction image at around 9 PM Tucson time (MST) tonight, February 22.

I mention this fact to draw your attention to a pretty cool feature of the Google Earth desktop application. It’s been around for a while, but you might not have heard about it. It’s called Live from Mars, and it shows you the orbits of MRO and Odyssey as they’re orbiting Mars right now. You can also see the image footprints for upcoming HiRISE (MRO) and THEMIS (Odyssey) observations. Even cooler, you can virtually ride along with MRO or Odyssey, your point of view tracking along those orbits.

To set it up, launch the latest version of the Google Earth desktop application. Find the little menu button that looks like Saturn, and click it to drop down the menu. Select Mars.

Once Mars comes into view, go to the Layers panel and open up the Mars Gallery group. You should see Live from Mars. Open up that group, and you’ll see Live from Odyssey and Live from MRO. Open up the Live from MRO group and you’ll find MRO Orbit, Fly Along, and HiRISE Footprints. Activate those and you’ll see a segment of the MRO orbit; you might see a HiRISE footprint or two, but our images are so small compared to the size of Mars that you might need to zoom in a bit to find them.

If you double-click the Fly Along item, your point of view will switch to that of MRO orbiting Mars. As you travel along, you’ll come across upcoming HiRISE observations, such as the one called out in the above image.

Cool, isn’t it?

A DTM (or synonymously DEM for Digital Elevation Model) is a grid, or raster, file describing elevation values at regularly spaced points, or posts.

HiRISE DTMs are made from two images of the same area on the ground, taken from different look angles. All the stereo pairs acquired so far are available here. Not all of these have been made into DTMs due to the time-intensive process. Creating a DTM is complicated and involves sophisticated software and a lot of time, both computing time and man-hours.

As mentioned in a previous post, the great advantage of a HiRISE DTM is the high resolution of the source imagery. As a general guide, terrain can be derived at a post spacing about 4X the pixel scale of the input imagery. HiRISE images are usually 0.25 – 0.5 m/pixel, so the post spacing is 1-2 m with vertical precision in the tens of centimeters.

The three basic stages of creating a DTM are:

1. Prepare the images for ingestion into the stereo software
2. Triangulate the images
3. Extract terrain

In order to prepare the images, we must first correct the geometry by removing any optical distortions inherent to HiRISE. Then the spacecraft pointing information at the time of each observation is gathered.

Triangulation is also called bundle adjustment. This step requires the most operator skill and time. The result is a transformation of the original images to epipolar space. What this means is that all the stereo information is now captured in the horizontal direction, or x-parallax. During triangulation, we also align the stereo model to MOLA elevations, so the end result is tied to the global elevation map produced by the MOLA instrument team. This is the same map that you see in the context map pane of every HiRISE observation page.

Once the images are triangulated, then terrain can be extracted. This step is computationally intensive, but automated, so it just takes a lot of computer time. The output of terrain extraction is reviewed for any artifacts or errors. These are edited out if possible. Since editing is extremely time-consuming, it is only done on easily corrected errors and in the areas of most interest to the researcher. The less editing we have to do, the better, so a lot of effort goes into preparing the images so that the input is as high quality as possible. The excellent contrast and value range of HiRISE imagery usually result in high quality terrain extraction that requires minimal editing.

After we have terrain, we can make other products, such as orthoimages. An orthoimage is a picture that has been orthorectified. This means that the pixels have been projected so that at each pixel it is as if you are looking directly down at the terrain. In the original stereo images, we rely on the fact that there are topographical distortions (parallax) to derive the elevations in the terrain model. In the orthoimages, all topographic distortions have been removed.

The final products are map projected using the same mapping definitions as the regular HiRISE RDR products.

A really useful (and cool) thing to do with the orthoimages is to drape them over the terrain for 3D viewing. Below is a subimage from the Newton Gullies DTM showing the imagery draped over the terrain.

You can see animated fly-throughs made with HiRISE DTMs by going to the HiClips page and clicking on the JPL Flythrough Clips. This is a great way to see and understand the geological relationships from a ground perspective.

Researchers use DTMs to take measurements and model geological processes. DTMs are very powerful research tools. In fact, almost every HiRISE DTM produced results in publication. There is a long waiting list for these products because they are so valuable and so difficult to produce. Several institutions involved with HiRISE contribute to DTM production to maximize the number of projects produced and to avoid duplication of effort.

Standard PDS products linked to the DTM project page are usually quite large files. The links provided will download the files to your system. To get a quick view of what the project looks like, click on the Extras links to see a reduced version of the products, displayed as images, grayscale, shaded relief and colorized altimetry.

Standard PDS products:

• The DTM in standard PDS image object (.IMG) format with an embedded label
• The left orthoimage at the same resolution as the DTM, in JPEG2000 format with detached label
• The left orthoimage at the resolution of the original image, in JPEG2000 format with detached label
• The right orthoimage at the same resolution as the DTM, in JPEG2000 format with detached label
• The right orthoimage at the resolution of the original image, in JPEG2000 format with detached label

Extras available in the PDS Extras directory (letters in parentheses correspond to PDS file names such as <Product_ID>.br.jpg):

• Browse (br), annotated browse (ab), and thumbnail (th) jpegs of the DTM as a grayscale image
• Browse (sb), annotated browse (sa), and thumbnail (st) jpegs of the DTM as a shaded relief image
• Browse (cb), annotated browse (ca), and thumbnail (ct) jpegs of the DTM as colorized altimetry
• Browse (br), annotated browse (ab), and thumbnail (th) jpegs of the lower resolution orthoimages

PDS product naming convention for HiRISE DTMs:

PRODUCT_ID = aabcd_xxxxxx_xxxx_yyyyyy_yyyy_Vnn
where
aa = DT, indicating it’s a DTM product
b = type of data

• E = areoid elevations
• 1 = orthoimage pixels from first image
• 2 = orthoimage pixels from second image

c = projection (others are possible but these are the important ones)

• E = Equirectangular
• P = Polar Stereographic

d = grid spacing (think of this as pixel scale in meters)

• A = 0.25 m
• B = 0.5 m
• C = 1.0 m
• D=2.0 m

xxxxxx_xxxx = orbit number and latitude bin from SOURCE_PRODUCT_ID[1]
yyyyyy_yyyy = orbit number and latitude bin from SOURCE_PRODUCT_ID[2]
V = letter indicating producing institution

• U = USGS
• A = University of Arizona
• C = CalTech
• N = NASA Ames
• J = JPL
• O = Ohio State
• Z = other

nn= 2 digit version number

Below is an example of the set of annotated browse images for the Russell Crater Dunes DTM.

The grayscale image of the DTM looks weird, if you have not looked at lots of these before, but keep in mind that the color of the pixels represents elevation. The higher the elevation, the brighter the pixel. Lower elevations are darker. The shaded relief is another way of visualizing the topography. The pixels are illuminated from a certain direction, to show the relief of the topography, rather than the elevation. It is also emphasizes any artifacts in the DTM. In the example here, many artifacts (errors) can be seen such as the faceted areas and boxes in the lower left and top of the image. These artifacts are usually caused by areas of low contrast (such as in this project) or sharply differing shadows. Most HiRISE DTMs will not have a lot of these artifacts, fortunately! The area of most interest to the researcher who requested this DTM was the long slope with the gullies, which was well-illuminated and had good contrast. So in that area, there were few, if any, artifacts. Adding color-coded elevation to the shaded relief creates the colorized altimetry map, where the lowest elevations are purple, green is the median elevation value, and white is the highest elevation. In the Russell Crater Dunes project shown here, the difference in elevation from the highest to the lowest point is almost 590 meters (~1935 ft.). That is a tall dune!!

We are happy to be able to share HiRISE DTMs with the scientific community and with the public. We will continue to release more DTMs as they become available, so stay posted!

There might not be any new HiRISE images to release (yet) but that does not mean we have been idle here at the HiRISE Operations Center. In fact, we have been very busy improving our existing images with new calibration and a different color stretch, making sure our entire data set is consistent, and preparing new product types!

For starters, our Extended Science Phase (ESP) images are now consistent, making use of all the latest and greatest fixes and improvements to our processing pipelines. These updated products are out now. The older Primary Science Phase (PSP) observations are still reprocessing; we should have them ready for an upcoming monthly release.

Next up, we have a fantastic new product called a Digital Elevation Model. Learn more about these products in an upcoming blog post!

Finally, several of our observations have been improved with updated descriptions.  For example, an image might have been taken of a crater that did not have an official name at that time. After the crater receives an official name, we try to go back and update the description for observations of that crater. Recently we had time to do that for a lot of observations. Unfortunately, the software used to update the EDR and RDR labels inadvertently corrupted the first few image data lines. Our attentive Targeting Specialists and Student Validators spotted the minor differences between reprocessed images and older versions. We have corrected the description update tools and reprocessed the EDRs from the 745 observations affected by this problem. Anyone who has downloaded HiRISE EDRs prior to the December 2009 release should check the list below to ensure any EDRs being worked with are not on this list. If the EDRs you have are from the observations on the list, you can check the “creation date” in their label. If the creation date is before November 4, 2009 then you should download the latest version. If the creation date is after November 4, 2009 then the EDR is good. The latest version of all of the EDRs for the following observations are now available on the PDS and on our website.
(more…)

We have now released all HiRISE images taken prior to August’s spacecraft safe mode event! Here are some statistics about our October 2009 release, which includes the images the HiRISE camera took of the Martian surface between Mars Reconnaissance Orbiter (MRO) orbits 14,200 to 14,499 (August 6, 2009 – August 26, 2009):

• 446 RDRs, 0.18 TB
• 6238 EDRs, 0.18 TB
• 5126 RDR Extras, 0.28 TB
• 12,464 EDR Extras 2.5 GB
• 16 Anaglyphs 0.001 TB

Totals for this release: 24,274 images, 0.62 TB

This brings our total released product numbers and data volume to:

• 23,122 RDRs, 12.2 TB
• 323,358 EDRs, 10.6 TB
• 196,058 RDR Extras, 15.6 TB
• 625,233, EDR Extras, 0.1 TB
• 1,192 Anaglyphs 0.5 TB

Total: 1,167,771 images, 37.7 TB

Just because we are not currently taking images does not mean we are slacking off. The Downlink team is busy reprocessing and validating all ESP observations. After reprocessing, these observations will all benefit from the same improvements we have made to our processing pipelines over the past several months. I also recently started reprocessing PSP observations, which is a much larger data set that will sync improvement to our processing pipelines made over the past few years! We are keeping busy and we are even getting help from the Uplink team while they wait for the go ahead to start taking new images of the Martian surface. Of course we all want that to happen as quickly as possible!

An exciting new paper came out in yesterday’s issue of Science magazine, with HiRISE team member Shane Byrne as the lead author. Water ice has been discovered being exposed by fresh Martian craters!

This is exciting for several reasons: first, these are very tiny craters – only a few meters (yards) across. This means they’re not excavating very deep into the crust of Mars. So the ice has to be really shallow – less than a few feet below the surface! Secondly, the location of these craters is surprising – they’re between 40-55 degrees north latitude. This is far from the polar regions, where we’d expect to find ice (for example, where the Phoenix mission landed at 68 degrees north, ice was found by digging down into the dirt).

The third exciting aspect of this ice is its purity. We’d expect this ice to be mixed in with dirt and dust and rock. Instead, we found that it’s 99% pure ice! (Only 1% is dirt mixed in.) This can be measured because we watched the ice disappear over time. By taking repeated images of the same spot, HiRISE got a time sequence as the ice slowly faded. It faded so slowly that it has to be almost all ice – a dirtier mixture would have faded much faster as it sublimated (went directly from a solid to a gas) in Mars’s extremely dry atmosphere.

Speaking of dry atmospheres, this also has interesting implications about the history of the Martian climate – there had to have been more water vapor in the atmosphere in the recent past than we previously thought. We still have lots of questions about how this ice formed, how much of it there is, and how many more of these craters we’ll find. Luckily, we’ve got a long mission ahead of us to explore these issues!

This discovery is also a great example of how the instruments on MRO work together. CTX initially detected these new craters as “dark spots,” and HiRISE followed up to confirm that they’re really impact craters. Some of those HiRISE images revealed some very bright white material, and then CRISM confirmed that material really is water ice. The instruments worked together to accomplish the best combined science. Go team! ☺

Here are some more detailed stories, images, and multi-media:

• Really nice movie with Shane Byrne talking about the discovery and excellent animations showing the locations of the craters and the time-evolution of the ice disappearing: NASA multimedia – then go to “Video Gallery” on the right, and click on “Mars – Exposed”.

• NASA press release, and all of the images and materials from the press conference

• UA news story

We’ve seen many more news stories & blogs – thanks for the interest, everyone! It’s great that everyone thinks this is as exciting as we do! ☺

It’s summer again in the southern hemisphere of Mars, so we’re continuing our mosaic of the landing ellipse for the lost Mars Polar Lander. ESP_013368_1035 was the first of the new images to be released, and we’ve gotten a lot of people asking where to send their candidates. You can either contact us directly, or add to the comments in our previous blog post about the search.

The Unmanned Spaceflight forums have a long discussion on the previous search efforts. Many candidates were proposed, and the community’s discussion about them is quite enlightening.

Emily Lakdawalla at the Planetary Society also started a coordinated search effort last year. I don’t know if that effort is still ongoing, but her page on how to use HiRISE images in the search is still a great resource. It includes examples of known hardware, cosmic ray hits and other artifacts, and more tips on searching.

In addition to the list of images on the previous blog entry, these new images have been released: (we’ll try to keep this list up to date as more are released)

• ESP_013368_1035
• ESP_013078_1030
• ESP_013223_1025
• ESP_013289_1035
• ESP_013566_1025
• ESP_013500_1035
• ESP_013711_1030
• ESP_013724_1030
• ESP_013935_1030
• ESP_013790_1035
• ESP_014001_1040
• ESP_014080_1040

Thanks for all your interest, and good luck searching!

9/2/09: ETA new images released in September PDS release.

Lately I’ve been helping out with the tours that we give of our operations center (HiROC) lobby and some public talks. Depending on the audience, we usually tell them a little bit about the HiRISE camera, its capabilities, and the MRO mission in general. We also talk about what we personally do at the operations center. The full-scale model of the camera and the “HiWall” are really nice exhibits for visitors. The highlight is usually when we show off what HiRISE has accomplished: color images, 3-D anaglyphs (everyone likes wearing those glasses!), and the recent addition of the fly-through movies has been very popular.

My favorite part is when people have questions for us – even when I don’t know the answers. Because, honestly, that’s what science is – we don’t always have the answers, but that’s what makes it exciting! It’s also fun to find out which aspects of the mission inspire other people, and I get a different perspective on what they think is interesting (versus just what I think is interesting!). Some of the questions are really good, too! We were talking with some middle-school students from El Paso, Texas, and their questions were so astute. One girl asked, “Does Mars have plate tectonics?” Another good question was, “How do we know about the interior of Mars?” These are great questions, and HiRISE is helping scientists to answer these and other questions, along with data from many other instruments studying Mars.

In case you were curious about these particular questions, like these kids were, here are some short answers and references for more information:
(more…)

Remember when I said we would start releasing data monthly to the PDS and public? We decided to work on improving calibration a little bit longer before we reprocess our data and start the monthly releases. Therefore, we are not going to have a June release (except for the usual weekly captioned image releases on Wednesdays), but we are getting closer to a regular monthly release! We are still ahead in our releases per PDS requirements, and we are preparing for the big reprocessing that is coming up. For example, our software pipelines have been updated to better automate reprocessing and we have hired two new student validators who will be responsible for visually inspecting all of the images as they are reprocessed. Training started this week.

Consider the May PDS release our practice run. Thank you for your patience…monthly releases of HiRISE images are indeed coming, but not quite as soon as we expected.

Planetary scientists used to keep new data from the spacecraft explorers of the solar system within the mission team for a lengthy period of time so they could make all the cool initial discoveries. Only later would the mission’s data sets be archived on the public Planetary Data System (PDS). Once archived, these data could then be used by the scientific community and public for further research and discovery.

Dr. Alfred McEwen, HiRISE principal investigator, decided early on that this incredibly powerful instrument should be “The People’s Camera”. This meant, among other things, that we would endeavor to make the data returned by HiRISE available to the scientific community and public as quickly as possible. We have PDS release requirements, but our goal has always been to beat those requirements. To do so, we needed to develop automated software pipelines to take the raw data and turn them into useful calibrated and geometrically mapped products. We also needed to develop the right PDS release tools, train a talented group of operations staff to validate the data and fix problems, and develop a website to effectively and beautifully showcase HiRISE images.

We now believe we have reached the point to be able to support a monthly release of recent HiRISE images to the public! This week we released the observations HiRISE took of Mars between orbits 11,600 and 12,599, or between January 16 and April 04, 2009. This makes us the first mission to release a data set to the PDS so quickly! Here are the statistics for this release, including the number of each product type released and their respective data volumes (EDRs are the individual uncalibrated image channels and RDRs are the calibrated, mosaicked, and geometrically-projected observations):

• 1,179 RDRs, 520 GB
• 16,861 EDRs, 459 GB
• 13,512 RDR Extras, 788 GB
• 33,152 EDR Extras, 7 GB
• 342 Anaglyphs, 51 GB

Totals for this release: 64,704 image products, 1.7 TB

This brings our total released product numbers and data volume to:

• 19,667 RDRs, 11 TB
• 278,807 EDRs, 9.5 TB
• 166,816 RDR Extras, 13.7 TB
• 529,095 EDR Extras, 0.1 TB
• 2,892 Anaglyphs, 0.5 TB

Total: 993,277 images, 34 TB

Those are various products for about 9998 Mars observations, and another reason why it makes no sense to hoard our data; there is too much of it and too few of us! The team scientists have plenty to do and there are plenty of discoveries to be made, old hypotheses to update, and new mysteries to solve.  The operations staff are now hard at work getting observations from orbits 12,600 through 12,999, or between April 04 and May 5, 2009, ready for the June PDS release. This involves making sure each observation has been processed by our software pipelines correctly, fixing any problems, and checking and double checking that the relevant image products are ready for release.  Sometimes we have to manually force an observation through the pipelines because some of its channels were lost during transmission to the Earth, or we might stumble across an observation we somehow forgot to send on to the color pipelines after it had been calibrated. There are spreadsheets to maintain, lists of problematic observations to keep (see the ERRATA.TXT file), and a variety of other tasks that need to be completed before the latest data set is ready for release.

Over the next few months we will see how this goes! It is a lot of work, but our desire for you to see these beautiful images of Mars as quickly as possible is strong. No promises, but we will also explore releasing completed observations even faster!

Using the HiRISE camera to take a special observation of a non-Mars target is a difficult but always interesting event for HiRISE Operations. While we have developed somewhat of a routine for regular imaging of the Martian surface, special observations require additional work that impacts our normal workflow as well as the science gathering of the other instruments onboard the Mars Reconnaissance Orbiter. Targeting specialists from Uplink already have so much work to do on a routine basis; adding in a special observation adds that much more work. Special observations are selected because they offer some scientific value that warrants the extra time, effort, and delay in routine science gathering.

We do not accept requests from the public directly regarding special observations.  Our very knowledgeable science team determines months in advance that the right geometry for a unique observation of a non-Mars target with scientific value is coming up. Over several iterations between Uplink and the science team, the target is planned in detail. For a target like Deimos, the smaller and more distant moon of Mars, the spacecraft needs to slew away from Mars to point the camera correctly. This is a dance that requires coordination between HiRISE, the other instruments (who will generally not be observing during this period), and the MRO platform.

For this opportunity,  we took two images of Deimos. The plan was to capture Deimos in the center of our CCD array so that the satellite would fall across our RED, BG, and IR color filters.  Uplink did a fantastic job with their targeting!  In the first observation – ESP_012065_9000 – Deimos lay across two channels of each color filter at the center of our array: RED4_0 and RED5_1, BG12_0 and BG13_1, and IR10_0 and IR11_1.  In the second observation – ESP_012068_9000 – Deimos was fully contained within RED5_1, BG13_1, and IR11_1. You can find more information about these observations here.

What did it take for Downlink to put these images together?  Well, Audrie and I came in on a Sunday (!) to wait for the observations.  Then I spent some time putting together preliminary images to send out to the team. During the following week I worked on registering the color filters to create the false color images.  See both images side by side here. Notice that green fringe around the first observation on the left? That is a bit of misregistration, something I could not seem to correct despite tweaking the position of the three color layers a pixel at a time. The first observation also required two separate stacks: (1) RED4_0, BG12_0, and IR10_0, and (2) RED5_1, BG13_1, and IR11_1.  After registering the two sides separately, I stitched them together using an ISIS tool called hiccdstitch.  That little notch you see at the top of the first observation is how the two sides almost but not quite line up. The two sides are slightly offset because their geometry is just slightly different.

Compared to the first observation, the second observation, confined to one channel each in the color filters, was wonderful to work with: no color balancing required, no stitching, and a relatively easy registration process!

GuyMac also helped make these Deimos observations a little easier to deal with than past special observations: he created a custom version of one of our processing pipelines that sharpens the image and brings out the colors a little bit. Once I had the observations registered, all I had to do was run them through his script for the really nice false color products you are now enjoying!