We’ve been imaging the northern plains for Phoenix since we started our mission (here’s a bunch of reconnaissance images on our website). The first images we got back showed lots of scary boulders (a close-up of one of our Transition images shown to the right), so we sampled other areas and searched for a relatively boulder-free landing spot. The area the Phoenix team finally chose is being called the “Green Valley“, not because of the “green light = safe to go” connotation, but rather because some geological maps made of the area happened to use green as the color for the valley. Perhaps coincidentally, Green Valley is also a town near Tucson, where both Phoenix and HiRISE are based. Whatever the reason, I like that the name has a lovely calm, comforting feel.

Once the Phoenix team picked out their landing site, we worked on a high-resolution mosaic of the entire 3-sigma landing ellipse (”3-sigma” means there is a 99% probability it will land within this area; see this great blog entry on landing ellipses at the Planetary Society). The Phoenix landing ellipse is shown to the left, along with the footprints of a number of HiRISE images. (This was before we were quite done with the mosaic.) These images have helped the Phoenix team characterize the regional geology and assess the safety of the landing site.

In addition to scouting landing sites, we’re also going to be involved with Phoenix during its prime mission on the ground. We’ve been planning and practicing several different ways of cooperating:

• Early Imaging: We are going to attempt to take observations of Phoenix on the ground several times in the first week of the mission. There are three images planned, two on the first day and one on “sol 5″. (The Pheonix mission will be counting time in Mars days, or “sols.”) Since the first two images are so early, there’s a good chance we won’t know quite where it landed yet, so the chances of seeing it are slim. The sol 5 image should be really good, though – we’ll know the exact landing spot by then, plus the image will have ideal lighting conditions and the highest resolution we can get.
• Relay: The Electra instrument on MRO will relay commands from Earth to the Phoenix lander, and it will relay data from Phoenix back to Earth. This affects HiRISE only indirectly – we’ll be planning our science imaging around the times Electra needs to be communicating with Phoenix.
• Cooperative Science: Phoenix and MRO have been planning coordinated science observations using different instruments on both missions. For example, when Phoenix takes a measurement of the amount of ice on the ground, they might want an image from HiRISE at the same time, to see how much frost is visible in the surrounding area.

Landing will be just the beginning of all these exciting activities. Come join us for a public celebration on landing day, May 25th! There are all sorts of events planned:

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.

1. The image is taken by the HiRISE camera, and is stored in up to 28 channels, two for each of the 14 CCD arrays of the camera. Each channel covers about half of the image. Of the 14 CCDs, 10 are red CCDs, two are blue-green, and two are near-infrared. The color CCDs are aligned with the center red CCDs.
2. The image is placed inside a buffer on MRO, awaiting transmission to Earth, along with science data from the other instruments on MRO.
3. The image is received in packets by the Deep Space Network (DSN).
4. After 4 hours of collecting data at the DSN, the Jet Propulsion Laboratory (JPL) puts the packets together for what is known as a “quick look”. The entire image generally has not yet been received by this point in time, but it is enough of the image that it can be processed to take a quick look at it. Subsequently, JPL puts together all of the data it has received every 4 hours and makes it available to the computers at HiROC.
5. After the files have been put together by JPL, then one of the computers at HiROC looks and sees that there is data on the JPL server and copies the data to our system at HiROC. This is the start of what is known as the pipeline, the system of programs at HiROC which process the images. This usually happens either via a direct connection to JPL (slower), or through the Internet 2(Faster, but sometimes can be bogged down).
6. The images are put together into a viewable format, using the minimum processing possible, and create what’s known as an EDR, or Experimental Data Record. This is done without calibration, stitching together the channels, or any other processing, aside from putting the image together. For an image which uses all 14 CCDs, there will be 28 EDRs. These generally speaking are of mainly scientific interest, but they will be released to the general public via the Planetary Database System (PDS). They will be in the standard PDS format.
7. After the EDRs have been created, they are converted to another format for ISIS. ISIS, the Integrated Software for Imagers and Spectrometers is a suite of tools used for processing images for most interplanetary missions, that was developed by the United States Geological Society (USGS). Most of the tools that we use at HiROC for processing our images are written for ISIS files.
8. After the ISIS files have been created, they are calibrated via a program called HiCal. This reduces the inherent noise of the camera to be more consistent with what is being photographed. All digital cameras create some level of noise, and while HiRISE is an extremely good instrument, it still generates a low level of noise.
9. After the individual channels are calibrated, then they proceed to a program called HiStitch, which puts the two channels of the same CCD together. As they are a part of the same CCD, this requires little processing.
10. Next, after each CCD been stitched together, the full CCD images run through a program called HiccdStitch. This program puts the different ccds together, making a mosaic for each color band. This requires some processing, as the ccds slightly overlap, and it can sometimes be difficult to match the different arrays exactly.
11. If the image has not been completely received, then at this point, the pipeline stops, until JPL has received the entire image, or if there are a few confirmed gaps in the image which we haven’t been able to recover. Transmission over the vast distance between Earth and Mars is not easy, and even the best systems have some small error.
12. After the image has been completely stitched together, then the image is geometrically projected. To understand this, realize that the images that HiRISE takes are flat, while Mars is actually round. Geometrical Projection alters the image so that the image points in compass directions, while correcting any distortions that are created by the ellipsoidal shape of Mars. With the geometrical projection images and the right software tools, such as qview for ISIS, the exact distance can be found between two point on the image. In order for this to happen, we must wait for information to be gathered on the exact position of the spacecraft. This is done by the nagivational team, based off of the downlink frequency. This takes two weeks after the picture has been taken, so Geometric Projection might take a while. This is the longest wait point of the operation. An image can be released from predicted information, however, most images will wait for the correct SPICE kernels to be calculated, in order to get the best information. If an image is geometrically projected from predicted information, it will be calculated with the correct info after it has been received.
13. The images are then validated by a team of students known as the HiRISE Validators. They check to make sure that everything in the pipeline worked perfectly, see if there are any gaps in the images, and other similar tasks. If they notice a problem, they contact the HiRISE Operators, who will take steps to resolve the problems, which may include passing part or all of the image through the pipeline again, or tweaking the software to make it work perfectly.
14. The image is converted to a format that the general public can use. Currently that format is JPG, or TIFF, but eventually we will use JPEG 2000.
15. After all of this, the science team members of HiRISE will look at an image to see if there is anything noteworthy. If there is, it is given a caption, and perhaps a press release. If not, it will be posted on the HiRISE website. They are also posted on the MRO website, and occasionally on others.

This process may take as long as a week or two to complete, depending on the load of MRO, scheduling concerns, load at HiROC, etc. The first image took about 9 hours to be completely processed after it was taken by HiRISE. The Victoria Crater picture, taken during a much busier time on MRO, took about 36 hours to make its way to our hands. This was in part due to the larger size of the image, as well as the cache of images already awaiting transmission on MRO to earth. The captions for the images taken during Transition imaging took anywhere from a few hours to a few weeks to write, and this will likely continue to hold. We at HiROC want to release the images we take as fast as possible to the public, and we are doing everything we can to realize this goal. Several shortcuts were taken during the Transistion imaging phase that allowed for images to be released quicker. For Primary Science Phase, this will take a bit longer because these shortcuts will not be taken, but we expect that we will release most images within two weeks after them being taken, shortly after we have finished receiving, processing, and captioning the image.

There are some variations to this process, for example, the Victoria Crater picture was released in a press conference jointly with the Mars Exploration Rovers (MER) team. Also, color images require extensive calibration and take a lot more time. However, this is the general idea. Currently the entire system, except for writing the captions and adding the images to our website, is essentially completely automatic for receiving and processing HiRISE images, due to years of preparation by the HiTECH and HiOPS teams.