About MOC images

You can now mark craters in new Mars images, but you should read this background information first.

The MOC camera is on Mars Global Surveyor,which has been orbiting Mars since September 1997 and is still mapping the planet. It was built for NASA/JPL by Malin Space Science Systems.MSSS also generated and serves the web-format MOC images you see on this site.

Some MOC images are very large, and you may have to scroll down (and sometimes horizontally, to the right) to mark the whole image. Some are so large that even a 1600x1200 display can’t fit them all at once. They also require more browser memory due to their size, and more processing power since your browser has to resize them to the correct width:height ratio. It isn’t practical for us to reprocess the images into smaller chunks for this study; we just use them the way that MSSS provides them.

MOC images are extremely high resolution (about 3 meters per pixel), so they cover a small area. Therefore, you may be looking at a vast stretch of sand dunes or a river delta or a boulder field, containing no craters at all. From the point of view of the task you have volunteered for, all you need to do is to mark no craters and send it back. Please resist the temptation to send email pointing out interesting images; we don’t have the staff to read or answer them. At this time, we are only focusing on quantifying specific feature types and are not able to do anything with qualitative descriptions. NASA does provide a number of educational sites for the public, but this is not one of them. You may learn something from this site, but you’re on your own.

We have screened out the images that are known to be corrupted by transmission errors, but there are a few overexposed and underexposed images. Please do not send anyone email reporting those. That isn’t a good use of your human perceptual abilities or our time; we could detect those with a computer program if we waned to.

Keep in mind that the image may not be coming from the top of the image. Craters tend to look inside-out when lit from below. There will be a little illustration showing you the lighting direction for each image.

MOC images are taken looking straight down, so circular craters should look circular. Since most craters are circular, if you see a lot of oval craters in an image, you may be looking at the slope of a mountain or the bowl of large crater. Just do the best you can.

We don’t have a special training session for MOC images. The closest we have is the regular crater-marking training. Please take that before trying to mark craters.

The MOC images are less processed than the USGS Mars Digital Image Maps from Viking Orbiter. They are closer to the raw images that come directly from the spacecraft. But you will be marking measuring small craters that no one has ever catalogued. If you are ready to take on the task, click here. If not, stick with the maps made from Viking Orbiter images.

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