We crossed the ten thousand observation mark this week; that’s our total number of observations since arriving at Mars. Roughly 9800 observations are of Mars (of course). Then there’s Phobos, Deimos, Jupiter, and the Earth and Moon (hope you were smiling!).

Over 9400 of these observations have been released to the Planetary Data System as JP2 files (over 9000 of these have color). As of today, 365 observations have been received after the end of the last PDS delivery, and are in the queue for the next one.

A handful of observations have data gaps in critical portions of the raw files (namely, science channel headers), or other severe problems that prevent processing from proceeding. We’re working on improved tools and procedures to alleviate the large amount of manual work to process those images; there’s a very good chance that the usable data can ultimately be recovered and released.

The rest (243 to be exact) are ‘CAL’ or calibration observations, used to verify settings on HiRISE, or obtain data that helps us remove noise and other imaging artifacts in our automated processing. They’re normally taken while on the night side of Mars with ’stim’ lamps on to provide a known, fixed light source.

Take a look at the plot below, which shows the cumulative number of observations received (in salmon) and the cumulative number released (as RDR’s, in mauve) as a function of time.

• The big steps are PDS data releases. The first was six months after beginning the primary operations in November 2006.
• There’s a missing step around December of 2007. That’s because we released a large number of color images, getting caught up with our color processing in lieu of a standard EDR/RDR release.
• The horizontal steps are not completely horizontal. The slope is our rate of weekly featured image releases.
• As noted earlier, just about everything is released, the totals are converging, the lag is 365 observations, or about a month at our current rate.
• The totals are a little less than 10,000; that’s the difference made by the CAL observations and the handful that currently can’t be easily recovered.
• There’s a ‘hump’ of received observations in late 2008, that’s the high data rate period (when Earth and Mars were closest).
• There are a few flat steps where no observations are received. One is the month-long solar conjunction period centered on Nov-Dec 2008, the safe modes of February 2007 and February 2008, etc.

We’re doing about ten observations per day at the moment. During the high data rate period it was nearly double that.

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More interesting data from our web statistics: rankings of the most popular images on our website. Some you’d expect to get lots of hits: special campaigns like Phoenix lander hardware and Phobos, and of course old favorites like a certain feature in Cydonia. Others have made a splash in the news, like the avalanche caught in action and a deep pit that might be the entrance to a cave – whether their popularity on our website is a cause or effect of the media coverage.

I find it interesting to see which “regular” images, out of the thousands we’ve taken, caught people’s attention – in May, for example, gullies in a crater wall and ridges in Huo Hsing Vallis (left) were popular. June saw lots of hits on this beautiful image of the north polar layered deposits (above) and this image of delicate-looking, multi-tendriled slope streaks.

In July, the “Mystery Mounds” (PSP_008778_1685 and PSP_008548_2205) were popular, presumably because they are so “mysterious” – ? (By the way, these two areas, despite their similar titles, are nowhere near each other on Mars.) Lesson learned: We should give more of our images “sexy” titles.

Our awesome technical group sent me the link to a page that calculates an overwhelming number of different statistics for our website. Visitors are broken down by country (lots of Canadian fans!), where they go, how long they stay, what browsers they use…. For the most part, I think people come to the HiRISE website to look at our images – which is as it should be! However, I was astonished to see how many hits the HiBlog gets. We don’t get all that many comments (except for the record-breaking MPL search entry), so here I was, thinking we were in a little bubble of self-absorbed anonymity, talking to ourselves….

My protective bubble burst when I saw the number of hits we got over the past few months:

• April: 36,200!
• May: 99,200!
• June: 44,500!
• July: 36,410! (as of this morning)

(The huge number of hits in May was probably due to the combination of the MPL search and the Phoenix imaging.)

…although this could just be 10 people who really love us, hitting “refresh” 4,000 times a month.

I don’t know how this compares to other websites, but I’m humbled and a little intimidated to find we have so many readers! I guess we should write more entries (and better ones!) We’re hoping to recruit some more team members to post, too. Ideas or requests for blog entry topics are welcome! Leave us a comment below.

The raw HiRISE image data needs to be cleaned up, and the HiCal pipeline is where this work is done. Now that the raw image data has been converted to a *.cub file format, ISIS tools can be used. These include hiclean, hipical, and hidestripe.

Hiclean does just what is says. Noise introduced into the image data by spacecraft electronics is corrected. Noise can show up as vertical and horizontal lines in the raw image and other periodic manifestations.

Hipical is a newer tool that performs calibration on the image data. For example, flatfield and gain corrections are performed by hipical. Hipical will be upgraded as we learn more about our instrument in its environment around Mars.

Hidestripe corrects a known striping pattern in HiRISE images.

We use other tools to collect even more statistical data about the newly calibrated image data. The HiCal pipeline will continue to be upgraded as our software matures. New statistics will be collected while corrections are added or improved.

After cleanup has been completed and a new *.hical.cub channel product created, HiCal creates a variety of jpeg browse and thumbnail images. The cleaned up channels are large, and for quick previews, these smaller jpegs come in handy.

Finally, HiCal lets the next pipeline – HiStitch – know that cleaned up channels are ready to be stitched together into CCD products.

Below is an example of raw data, prior to going through the HiCal pipeline. This image sample was taken from TRA_000873_1780; “Victoria Crater” at Meridiani Planum.

Below is the same image sample after going through the HiCal pipeline (notice that the bright vertical line in the center and the faint vertical lines throughout the image have been correctly removed by HiCal):

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!