Our latest release includes more products from the original Phoenix descent observation, which include the color CCDs hand-mosaicked over the red filter CCDs. We’ve also been working with the Phoenix and MRO engineering teams to identify the location of the heat shield in the image (left). It’s pretty incredible that we caught the lander just after releasing the heat shield – a few more seconds, and it would have been out of the scene.

Emily Lakdawalla continues her excellent blog coverage in this article, which does a great job of explaining some of the reasons why this image was especially difficult to take. Along the way, she includes a tutorial on TDI (Time-Delay-Integration), written by one of the engineers that helped build the instrument. TDI is the method HiRISE uses to gather lots of light into its CCDs, and it’s one of the reasons we get such high signal-to-noise in our images. It’s a complicated concept, but it’s an important one for understanding HiRISE’s incredible imaging abilities, as well as its limitations.

From her blog post:

This is a fascinating story showing how necessary it sometimes is to have a deep understanding of an instrument in order to understand the data that comes from it. …It can be dangerous to read too much into space images until you have studied how the cameras really work.

It’s a great post – she deserves a cookie!

Here are 40 RGB color images from the 1500 – 1600 orbit range of MRO.

View Images

There are, as always, many magnificent images here. Some of the noteworthy observations are:

PSP_001521_2025 and PSP_001501_2280: On the HiRISE web site you can see diagrams made by Tim Parker show the locations of various parts (lander, backshell, heatshield or parachute) for Viking Lander 1 and Viking Lander 2. It’s possible they aren’t in the color strip (I haven’t found them)!

PSP_001508_1245 and PSP_001510_2195: These two exhibit a “glow” pattern of saturated pixels due to high TDI (Time Delay Integration) settings on the blue-green CCDs. (All of the exposure settings are chosen for each observation based on a photometric model of the scene).

PSP_001538_2035: This is a rim-to-rim section across a crater called Tooting that is about 30 kilometers in diameter. It’s also interesting to note how the altitude of the rims, when combined with the large off-nadir roll angle (23 degrees), leads to an oddly bowed geometric projection. But it is correct; as the terrain rose, fell, and rose again from HiRISE’s angled point of view, the center of the ground track deviated slightly east or west from a true great-circle line.

PSP_001558_1325 and PSP_001593_2635: These dune fields are striking, forming incredible patterns.

PSP_001582_2245: Looking like a super-sized area of dried mud, the polygonal cracks in this image are amazing.

Updated (2008-Apr-10)

Last week we had a rare event: HiRISE turned off! We call this safe mode, because it’s a safety measure built into the instrument’s software. Whenever any of the sensors starts going out of bounds, like temperatures or voltages, the instrument powers down to prevent damage to the electronics. In this case, one temperature sensor went over its upper limit of 35 degrees Celsius. It’s pretty disconcerting when something unexpected like this happens, but at least we know the instrument is protected.

We had the difficult detective job of figuring out what went wrong. It was clear early on that the instrument overheated, but we couldn’t figure out why. Our tool that predicts the temperatures (”HiTemp”) didn’t predict anything that hot. We didn’t take a really large image, which would heat us up (at least, nothing bigger than normal! ). The local operations team worked with the health & safety people, the spacecraft engineers at LMA, and some of the software developers at Ball Aerospace that originally designed HiRISE. Together we all investigated the problem.

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Spacecraft missions are complicated endeavors that result in a wealth of scientific and engineering data. Long after the mission has ended, these data can be extremely useful for later study and discovery. With so many missions over so many years, how can later generations find and make use of these data?

The solution for many NASA missions has been the development of the centralized Planetary Data System (PDS). The PDS is several things: a collection of websites, a search capability, an archive, a database, a learning tool, etc. The PDS Imaging Node is located at http://pds-imaging.jpl.nasa.gov/ and acts as “the curator of NASA’s primary digital image collections from past, present and future planetary missions.” These missions include Voyager, Galileo, Cassini, and many more. Now the Mars Reconnaissance Orbiter (MRO) has been added to the list, with the HiRISE team releasing our first several months of image data.

• MRO PDS page: http://pds-imaging.jpl.nasa.gov/Missions/MRO_mission.html
• MRO Product Search page: http://pds-imaging.jpl.nasa.gov/search/index.jsp
• HiRISE Volume: http://hirise-pds.lpl.arizona.edu/PDS/

What we have released is an archive of the HiRISE Experiment Data Records (EDRs) and Reduced Data Records (RDRs). EDRs are in the *.IMG file format and represent individual CCD channels (remember, there are 14 CCDs in the HiRISE camera and two channels per CCD, for a total of 28 channels). These EDRs are cleaned up, calibrated, stitched together, and mapped to Mars’ geometry, resulting in the RDR products. RDRs are in the *.JP2 and *.LBL formats. JPEG2000 is the technology that enables us to offer our gigantic images to the scientific community and the public in a timely and efficient manner. An observation’s image data are in the *.JP2 file and its meta data are in the detached *.LBL files. To view these products, JPEG2000 compatible software is required (see our site for a list of offerings).

While we have been trying to release up to five captioned images a week for the past few months, the PDS release represents several hundred images, most of them without captions. You can find them using the PDS search capabilities, and you can also find them on the new HiRISE site, unveiled today to coincide with this first PDS release. The redesigned site focuses on the images while providing, hopefully, a more user-friendly interface:

• HiRISE Site: http://hirise.lpl.arizona.edu/
• “About Our Redesign”: http://hirise.lpl.arizona.edu/profil.php
• Images released to the PDS: http://hirise.lpl.arizona.edu/pds_release.php

As word gets out about the new site and the PDS release, you may experience some site slowness. Please be patient, and thank you for your interest!

To give you some idea as to the size of a HiRISE image, I’ve put together a few screenshots from our planning software, HiPlan. These images compare the HiRISE footprint with that of the the THEMIS instrument aboard Mars Odyssey. These screenshots are shown below as thumbnails; click on a thumbnail to see the screenshot at its actual resolution.

I should note that these are not planned to be actual HiRISE images; I was using HiPlan in test mode while working on the display of the individual HiRISE CCD footprints.

Take a look at this screenshot. It covers a small region of Mars roughly one degree across and slightly less than a degree tall:

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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.

We mention our automated pipelines a lot, so I might as well jump in and provide some more information about them, on top of what might already have been mentioned before. I will start with the first one – HiDog – in a moment, but first, let me introduce Watchdog.

You should know by now the route our data takes: from the HiRISE camera on MRO to storage to spacecraft radiation to the Deep Space Network radio telescopes here on Earth to the ground data system network to JPL in Pasadena, CA to the University of Arizona campus network to our servers in the HiRISE Operations Center. Our Watchdog software, well, watches the JPL servers for new HiRISE raw image data. When it sees a new raw channel file (2 channels per CCD, up to 14 CCDs per observation), Watchdog flags that file as ready to be downloaded by HiDog.

HiDog is the first automated pipeline. It wakes up every few minutes to see if the Watchdog has flagged any new files (basically, it is checking a sources table in our database). If there is nothing new in the sources table, then it goes back to sleep. If there is something new, HiDog wags its tail, rapidly downloads the file, checks to see if there are any gaps in the data, and then tells the next pipeline that a new image channel has arrived in Tucson, ready for further processing. Then, it checks to see if there are any more files ready for downloading, and goes back to sleep if there are not. Sweet dreams, little doggy.

Over and over again, 24 hours a day, 7 days a week, the Dogs are ready and waiting for the latest HiRISE data from Mars.

Next time…the EDRgen pipeline.

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.

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