2. Ok, so you've had a good look at "the rock" imaged by the Mars Exploration Rover Spirit (MER-A) on sol (Martian day) 66. You have some perspective as to where it sits (next to the rim of Bonneville crater) and what's around it (near a large relatively darkly colored rock and close to a smaller rock with an X on it's end.) You have also seen that at first it appeared that this was just a rock and only upon close inspection of the enhanced anaglyph (3d) version did it reveal that there is the slightest indication of something just peeking around it. In 3d we can see this object in cite class="jcetooltip" title="silhouette |ˌsilo͞oˈet| noun
the dark shape and outline of someone or something visible against a lighter background, especially in dim light.">silhouette behind and both along the upper third of the left side and sticking up from the middle to the right edge.
Moving Closer
Up to this point I have intentionally used very few illustrated or annotated photographs to tell this story because I'd like the images to speak for themselves to the extent possible. Personally, I prefer to examine things for myself and reach my own conclusions without undue external influence or direction. Annotations, boxes and arrows can tend to obscure some details as well. However, there is something to be gained from the judicious use of these types of additions to focus attention on key issues and to make the narrative clearer. With that in mind in the following panoramas I have highlighted an area of focus. As always you can find the unedited NASA originals with links to the source files in the Panorama and Mosaics Archive.
Backtracking for just a moment to sol 66 as seen in Figure 2 below, I have used a box to track the area we are interested in as the rover moves towards the crater rim. You will have seen this image, albeit without the box, in the previous article. I am starting with this here as we then zoom in to remove any doubts as to the fact that this is the same rock on sol 66 as well as on sols 67, 68, 69 & 70.
The timeline for the images is, sol 66 (Figure 2), sol 67 (Figure 1 above) and sol 68 (Figures 3-5) and sol 68 (Figures 6, 7 & 9).
Compare the region marked in Figure 2 with Figure 1 at top and then with Figure 3 below, it should be clear that the area in each picture is the same. As a reminder, the image in Figure 2 is cropped in a way that it appears that the rover was closer than it really was.
On sol 67 the rover had not yet completed the climb to the crater rim located 4.1 - 6.4 meters above the surrounding plain [Golombek et al., 2006] as it then did on sol 68. The perspective relative to the rock's horizontal plane in Figure 1 & 2 is very similar despite the rover's increased elevation because of the use of different cameras. The image taken on sol 66 used the mast mounted NavCam positioned 1.54 meters above the Martian surface. The PanCam pair is mounted on the same mast and next to the stereo NavCams. The image on sol 67 was taken with the front left HazCam mounted 52 cm (20.4 inches) above the surface. Think of the change in the angle of view from the use of the PanCam or the NavCam rather than the HazCam as the being difference between standing up and being at knee level or 1.34 meters (52.8 inches) lower.
Figures 3-9 were taken after the rover had finished the climb and used the PanCam to capture the rest of the images you see below.
The enhanced versions in Figures 6 and 7 reveal details not apparent in the original. For perspective on the effect that these changes have had, Figure 6 includes a bit more of the surrounding area.
In the following enhanced image I have more closely cropped the panorama to further isolate Kilroy and his rock. The area surrounding Kilroy has some distinctive rocks that serve as reference points. As mentioned previously there is a visible vertical "seam" running down the middle of the image is an artifact from the electronic stitching process used by NASA technicians to create the original mosaic image. By the way, this is not a particularly easy task to accomplish with perfection. Try manually assembling adjacent raw image frames from NASA's servers into a perfect whole to get an appreciation of the complexity of the task. Undoubtedly the task has become substantially automated and improved in the time since 2004 when the panoramas were completed.
Figure 8 shows a three image comparison of an isolated Kilroy taken from three different versions of the same image; an enhanced image, the raw underlying constituent image and the original composite panorama. This demonstrates how a bit of image enhancement can reveal details that are present but not obvious.
https://kilroyonmars.com/analysis/75/analysis/199/at-the-crater-s-rim#sigProId44b6b1261b
References and Notes
1Maki, J. N., et al., Mars Exploration Rover Engineering Cameras, J. Geophys. Res., 108(E12), 8071; doi:10.1029/2003JE002077, 2003.
2Leger, P. Chris, et al., Mars exploration rover surface operations: Driving spirit at gusev crater. Systems, Man and Cybernetics, 2005 IEEE International Conference on. Vol. 2. IEEE, 2005; doi:10.1.1.297.544110.1.1.297.5441
3 Smith, Gregory H., et al., Optical designs for the Mars' 03 rover cameras. International Symposium on Optical Science and Technology. International Society for Optics and Photonics, 2001; doi:10.1117/12.449558
An analyst born 53 days before NASA. A midwesterner now living in the southeast.