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!

We’ve just released 1008 new HiRISE images to the PDS! (See main page, or click here for the catalog.) This release covers orbits 8200 – 9299 of the primary mission, or in other words, the end of April through the end of July. That means we’re releasing data that’s only about 6 weeks old! This is awesome – I’m so impressed with the downlink team! The amount of work required to process these images is astounding, let alone prepare and post everything for an official release.

Here are a few examples of cool images, which were previously unreleased:

• PSP_008248_2640, Polygons and spots on defrosting dunes (right)
• PSP_008269_1395, crazy weird stuff in Hellas Planitia (be sure to look at the whole browse image on this one!)
• PSP_008322_1865, Multiple generations of slope streaks on a crater in Arabia Terra (left)
• PSP_008343_1430, Gullies on mesas in Gorgonum Chaos

I’ve only looked through the first few pages in the release. I know there are a lot more amazing images in there, so if you’re browsing through the images, post some of your favorites below!

As described in a previous post, HiRISE color images are made by combining images in three different wavelengths of light, infrared (IR), red (RED) and blue-green (BG). The incoming light from the surface of Mars is separated by a filter into these three parts of the spectrum. The detectors that receive those wavelengths of light then build up the three separate images of the same place on the surface. The IR and BG detectors are above and below the RED detectors in the HiRISE focal plane, so they are imaging the same place, but at slightly different times. In order to create the color products, the three separate images have to be stacked one on top of the other. Lining up these images perfectly with each other is called coregistration.

This process seems simple in concept, but in practice it is quite complicated. There are three factors to account for:

• Relative timing
• Pixel binning
• Spacecraft jitter

First of all, HiRISE nearly always uses different resolutions for each color. For instance, RED might be at a scale of 25 cm/pixel (bin1) while IR and BG are at 1 meter/pixel (bin4). This “binning” minimizes the amount of data that has to be sent back to Earth, which is the most important constraint that HiRISE needs to deal with. Another reason for binning color is to improve the signal-to-noise ratio (SNR). This means that you can get a better signal by combining pixels at the expense of spatial resolution. In order to get the binned IR and BG images to line up properly, they must be enlarged to match the dimensions of the RED image. For example: RED is bin1, IR and BG are bin2. The RED image will be 2000 pixels wide by 40,000 pixels long (for example), the corresponding IR and BG images will be 1000 pixels wide by 20,000 pixels long. So the first step is to make the dimensions of all three images match.

Now the relative timing is easy to take care of. The start time of all images is a known quantity, and does not change from image to image. We know exactly when the BG detector starts imaging, followed by the RED detector, followed by the IR detector. So the beginning of each image is offset by a fixed amount. Once the images are shifted by this fixed offset (accounting for binning), they will be approximately lined up.

This brings us to the third factor in coregistering images — spacecraft jitter. Because HiRISE is imaging at such a high spatial resolution and at great speed, tiny motions of the MRO spacecraft cause slight variations in where the surface features appear in each of the three color detectors. Imagine that HiRISE is taking a picture of a 1m sized boulder on Mars. If the rock shows up in line 100 of the RED image, and we have already accounted for the relative offsets of the detectors and for binning, then the rock should also show up in line 100 of the BG image. But say we look and it is actually in line 99. Now when we try to stack the two images, the objects in them won’t line up exactly. Our color processing software corrects for this by holding the RED image fixed, and adjusting the corresponding BG and IR images to match it precisely. This is not a perfect process, but most of the time it works extremely well.

Producing the color HiRISE products is not a trivial process. But it is to a point where the processing is automated so new data is released without delay. Enjoy the colorful view!

To conclude our exploration of the pipelines that take raw channel files and create a beautiful, unmapped mosaic, let me introduce the Stitch pipelines: HiStitch and HiccdStitch.

The HiStitch pipeline combines the matching HiCal products for the same CCD into one more-or-less lined up CCD cube file. HiccdStitch combines these HiStitch cubes into RED, IR, and BG mosaics.

Both pipelines take some time, as overlapping pixels are accounted for and brought together. After these mosaics are created, additional steps create smaller jpeg files for easier viewing, and full-sized jpeg2000 files. We use these jpeg2000 files for validating our images.

There are later pipelines, but we first validate the HiccdStitch products: Did the previous pipelines work correctly? Did the uplink team command the camera correctly? Is there haze or clouds obscuring our view of the surface?

If everything looks good, and we have received the correct reconstructed SPICE ephemeris data, then the geometry pipelines are invoked. These pipelines project the images mathematically to a model of Mars and add geometry data to the images so that each pixel becomes a point on Mars with latitude and longitude coordinates.

Well, it’s been a while since we’ve been posting a lot, so I thought I’d just give you guys some kind of an idea as to what we’re doing these days.

The uplink team is constantly looking where to point the camera next. There is a program which is in beta testing now called HiWeb which allows scientists and other people to input suggestions. The Uplink team reviews the suggestions in the database, assigns a priority to each of these suggestions, and then finds when we can point the camera at the part. They also make sure a certain percentage of the upcoming pictures are assigned to look for a Phoenix landing spot, as this is a high priority item at the moment. They are still learning exactly how to best command the camera, and are constantly sharpening their skills.

The downlink team is making sure operations run smoothly at HiROC. They are verifying that the processing has taken place, make sure that the images have been calibrated correctly, that there are no image processing artifacts on the images we are about to release. If there is any artifacts created from processing the image, the source of the problem is identified and fixed, and then the image is reprocessed. While previously we have sent images to the public that had some small processing artifacts during the post-MOI and Transition imaging, we currently are waiting until the images have been completely validated. The downlink team is also taking a quick look at each image that comes down, and making sure there isn’t something unexpected, for example, haze at Mars, lots of saturated pixels, etc. If any such problems are found, they notify the uplink team, to ensure that we don’t have continuing problems. These problems are very rare, but on occasion happen, due to the changing nature of Mars. (more…)

After a channel of raw data has been downloaded and converted into an *.IMG file, we need one more conversion before cleanup of the image can begin.

The EDR_Stats pipeline creates a *.cub file from the *.IMG file. These cube files are the file type used in ISIS 3.0, an image processing software package provided for planetary science missions by the United States Geological Survey (USGS). This package contains an entire suite of useful tools, many of which are used by our pipelines.

During the creation of a cube, a variety of statistics are gathered. For example, the number of gaps, saturated pixels, calibration pixels, and other pixels are counted. Image mean, standard deviation, and other statistics are also calculated. EDR_Stats takes these results and uploads them to our database. The resulting cube is archived in our storage directory.

The final EDR_Stats pipeline step lets the next pipeline – HiCal – know that an image channel cube file is ready for calibration processing. Let the cleanup of image data begin!

The Planetary Society has an excellent article entitled “HiRISE Image Processing” based on Tuvas’ HiBlog post “Processing images at HiROC“. Both articles explain the EDRgen pipeline very well.

It is important to note that while there are a multitude of image formats available, Experimental Data Records (EDRs) are a standardized way of packaging planetary science data sets for release to the world while ensuring future access to said data. In the case of HiRISE images, there are two components to an EDR product: (1) the image data and (2) the label.

The EDRgen pipeline uses a program called HiRISE_Observation to create an EDR from the original channel raw data. The image data is converted into a file type with the extension *.IMG and important information about the observation is attached to this *.IMG file in the form of a text label. This label includes information about this mission; the observation name, commanding, time, and temperatures parameters; and other useful information.

After the EDR is created, it is archived in our storage directory hierarchy (we follow a hierarchy that includes mission phase, orbit range, and observation ID). Finally, the database sources table for the next pipeline – EDR_Stats – is updated with the location of the new EDR. Further processing of this EDR, in a different format, is necessary to start cleaning up the image.

How long do each of these pipelines take? HiDog generally downloads a new channel file in a few minutes or less. EDRgen can create a new *.IMG file in a few minutes or less, and we have a few EDRgen pipelines working in parallel. The fact is, most of the pipelines are incredibly fast on our processing cluster. Later pipelines that stitch and mosaic take significantly longer, but rapid progress in computer technology have blown away early conservative estimates of how long HiRISE image processing would take.

I decided the blog does not have enough pictures, so a few of us gathered around a MacBook Pro and said “Cheetos!”. Audrie is on the left, I’m next, Kite is next to me, and Tahirih is on the right. Yes, Kite has Princess Leia hair. No, I’m not a nerf herder. Who’s scruffy-looking?

Audrie, Tahirih and I did not previously appear in pictures on HiBlog because during transition imaging we were busy working in our offices and Tuvas for some reason did not visit us. We feel so left out (joking)! The three of us make up HiRISE Downlink Operations, which includes downloading new images, processing them, and image validation (the Student Validators also participate in this task). Audrie also works on instrument monitoring and safety. Tahirih also does most of the geometry processing. I also eat cheetos and chocolate cake. When Kite is not busy with HiRISE Uplink tasks – which is generally NEVER – she is blasting her way out of impossible situations that often involve walking carpets.

Some of you out there may be asking: what happens to a HiRISE image between the time that it is taken and the time that it is released to the public? Well, I’d like to give a summary here.

(more…)

Perhaps the most amazing event last week was that we were able to help the Cornell/JPL team plan a rover drive. The Victoria Crater image was coming in, though with data transmission gaps that meant manual processing was needed. At the same time, the load on our partially-upgraded internal network and servers was approaching a crisis-level condition. The image—if we got it—was expected to be released less than 18 hours later, at a joint Rover/HiRISE press briefing, which didn’t allow much time for analysis and color processing.

Finally, it was at this moment that Steve Squyres (Principal Investigator, Mars Exploration Rovers) called our Chris Okubo and asked for whatever we had in helping plan a rover drive “right now.” Chris O. is normally the most laid back person on the team, which kind of masks the fact that he is a very sharp, hard-working geologist, and somehow also found the time to plan more HiRISE observations than anyone else, by a substantial margin. Chris was at this moment as close to agitated as I’ve ever seen him.

But with some quick work by the Downlink Operations crew (Tahirih in particular), the rover drivers were able to get what they needed, and transmit instructions that would place Opportunity closer to the edge of Victoria Crater.

It seemed to be the dramatic climax to an incredible week.

The color image of Victoria Crater, our first color image from science orbit, is stunning, check it out if you haven’t already!

Shown below is HiRISE’s eagle-eyed view of Opportunity from 168 miles above.