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!

A lot of these FAQ have to do with the different data products we release, and how we plan and process the images. There are also definitions of some of the terms we use, which we know can be confusing! Hopefully you’ll find these helpful. If you have questions about HiRISE images, how we work, or anything else, check out our FAQ. If your question isn’t answered in there, please ask us your questions below in the comments. We’ll try our best to answer them, and the FAQ will grow!

One FAQ I’d like to address is, “Why don’t you take an image of X?” where “X” is the asker’s favorite spot on Mars or other celestial body. My answer:

If X is on Mars, we will try to image it eventually. Someday (hopefully soon) we will release HiWeb, a tool that will let anyone suggest HiRISE targets. Then you can enter your favorite spot into our database of suggestions. However, HiRISE only gets to image ~1% of the entire surface of Mars in our primary mission, so keep in mind that we have to be extremely picky about what we image. Each suggested target is vetted and prioritized by the science team, then it goes through a lengthy and complex planning process, each step of which has the potential for kicking the target out that cycle. Things that can prevent a given target from being acquired include: limits to how far we can roll off nadir, conflicts with other instruments, conflicts with higher-priority HiRISE images, spacecraft power constraints, danger of the camera overheating, and limitations on the amount of data we can store on board and downlink via the DSN.

If you’re looking for answers to questions about other missions, or the red planet in general, here are some links that might help:

• MRO mission fact sheet (Clicking this link will download a PDF document)
• Phoenix mission FAQs
• Mars Fact Sheet
• Atlas of Mars
• More about the planet Mars

One by one, we’re introducing new uplink personnel to the complex system of uplink planning. In fact, each cycle so far has been planned by a new Targeting Specialist, so we’re still in the midst of a lot of training. Once we each get through one cycle, I think we’ll notice a big improvement in efficiency. Starting with cycle 007, new CIPPs (Co-Investigators of the Pay Period — the science team members who help plan observations for a given cycle) will also be visiting HiROC for a few weeks while they learn about the planning process. So the “cycle” of training continues, with Targeting Specialists training each other, and then passing that knowledge on to new CIPPs. We expect this to persist through PSP, since there are ten Co-Investigators, plus their post-doctoral researchers and students who may get involved.

Special activities like off-planet observations provide a little variety, a change from the cycle of planning and the constant cascade of downlinked data. Some of these approaching activities include:

• Stellar calibration — 11 January
• Updating the LUTs (Look-Up Tables) we use to convert from 16-bit to 8-bit data on board the spacecraft — mid-January
• Deimos calibration — late January

We’re currently developing and testing the command sequences for these events.

To tell the truth, some of us are experiencing a little bit of a lull. We’re in conjunction right now — this means that the Sun is directly between Earth and Mars, so we can’t communicate with the spacecraft. (Here’s a link with a few diagrams to illustrate this.)

The HiRISE instrument is turned off, and we’re not taking any images. However, there are other activities going on at HiROC….

We start imaging again on November 8, and a few of us are already planning for that. PSP, the Primary Science Phase, is divided into two-week cycles. The first cycle is rm001, the second rm002, etc. Each cycle has a Targeting Specialist assigned to it (this one isn’t me, or I wouldn’t have time to write this!). The Targeting Specialist works with a member of the science team, the “Co-Investigator of the Pay Period,” (”pay period” because of the two-week cycle) or CIPP. The CIPP helps to choose scientifically important targets, and the Targeting Specialist does the scheduling and commanding. They work together on coordinating with other teams, choosing camera parameters, etc. There are a lot of details that need to be worked out!

We’re also building commands for a few special calibrations that will occur during the first cycle. On November 9th, we’re going to take a series of flat field images for calibration purposes. For these, the spacecraft will yaw (rotate around the normal axis) 90 degrees. Then when we take an image, it will smear across the whole field of view, giving us as close as we can get to a uniformly bright image. Once we average this over a lot of observations, we will divide our images of Mars by this as one of the calibration processing steps.

We will also be participating in a Deimos observation on November 13th. The calibration is actually set up for CRISM, and we’re just riding along, so the viewing conditions are not ideal for HiRISE. So don’t expect a fantastic HiRISE observation of Deimos! Instead, we’re taking this opportunity to measure stray light. Stray light is the extra scattered light that gets into the camera’s optics. We’re pretty confident that not much stray light gets into the excellent optics of the HiRISE camera, but we want to make sure.

Of course, the work never really stops, so we’re all busy with other things, as well — updating procedures and software, training new people, and trying to get ourselves organized and prepared. We want to be ready for the onslaught of images that will start in a few weeks and continue for (at least) the next two years!

NASA story: During Solar Conjunction, Mars Spacecraft Will Be on Autopilot

Every HiRISE image (or “observation”) is identified by a unique ID. Think of this observation ID as the name of the image. The basic form of the ID has three parts: a mission phase, an orbit number, and a target code. Our first transition phase image, for example, is TRA_000823_1720.

The mission phase is a three-letter abbreviation. “TRA” is the transition phase. Starting in November, you’ll be seeing “PSP” for “primary science phase,” which lasts for two Earth years.

The orbit number is a six-digit, zero-padded number. “000823″ is the eight hundred twenty-third orbit of MRO around Mars. MRO is in a roughly polar orbit around Mars, meaning the orbit is nearly perpendicular to the planet’s equator; this sort of orbit is typical of missions designed for mapping, because it provides coverage of the entire planet. The orbit number increments by one whenever we cross the planet’s equator on the nighttime side.

The target code indicates the target of the observation. If the number is between 0000 and 3595, it is the angle between the nighttime equator and the latitude of the center of the observation, multiplied by 10. It is measured to the nearest half-degree. The nighttime equator is 0000, the south pole is 0900, the daytime equator is 1800, and the north pole is 2700. 1720 is at latitude 8° S.

If the target code is between 9000 and 9303, it indicates an off-planet target, such as Deimos, Phobos, or a star.

And that’s how you identify a HiRISE image. In practice, the HiRISE team talks about them by dropping the mission phase code and the orbit number padding. Our first image is simply “823 1720″ amongst the team. Formally, however, it will always be TRA_000823_1720.