Petaled 'Crater' in Mars Terra Sirenum

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Submitted by Al.Reaud on Tue, 05/31/2011 - 13:43

NOTE: Updated 10/11/2016, links verified.

Analysis of Mars Odyssey (THEMIS) data release image number: V01354003.  All source images used are courtesy of NASA/JPL/Arizona State University(ASU).

Following the THEMIS data release for V01354003, this investigator will attempt to show that the petaled 'crater' at (483, 2964) in the Apparent Brightness Record (ABR) image is a feature that is not meteoric in origin, but is instead a geyser or similar feature of tectonic nature.


Table of Contents:

  1. Image Sources.
  2. GIMP Cubic Spline Interpolation Verification for Feature Scaling.
  3. The 'Petaled Crater'.
  4. Shape from Shading (Photoclinometry).
  5. Comparison to Splatter Crater.
  6. Comparison to Other Features.
  7. Adjacent Mars Orbiter Camera(MOC) Images.
  8. Apparently Square Crater and 'Underground Structures.
  9. Conclusion.

Image Sources:

First seen as Daily Release 20021002 on the Mars Odyssey Themis website for October 2, 2002.  This is a visual image only, at a resolution of approximately 18 meters/pixel, with no corresponding MOC image (see Adjacent Mars Orbiter Camera(MOC) Images, below).  The size of the feature of interest is relatively small, with a linear span of approximately 30 pixels, or 570 m (1870 ft).  The approximate area of the petaled 'crater' feature is 810 pixels, or 262,000 m² (861,000 ft²).

Unretouched crop of feature at (483, 2964) on V01354003ABR.IMG and surrounding area. Processed crop of feature at (483, 2964) on V01354003EDR.QUB from a NASAView GIF including surrounding area.
Figure 1. Figure 2.

Figure 1 is an un-retouched crop of the feature at (483, 2964) in V01354003ABR.IMG (3.76MB), and surrounding area, using GIMP coordinates, after conversion via NASAView to GIF format.  The top left corner of the image as displayed in GIMP is coordinate (0,0).  Figure 2 is taken from V01354003EDR.QUB (3.76MB) also converted with NASAView to a GIF format file, then further processed with the GIMP Image --> Colors --> Adaptive Contrast tool, using a value of 25 for the iterations, and a value of 35 for the detail size.

GIMP Cubic Spline Interpolation Verification for Feature Scaling:

Due to the reduced size of the image, a short movie showing the scaling process is included to verify that the GIMP cubic spline scaling algorithm is not introducing significant distortion into the image.   Due to the large size of the movie, it will not be included in the page.  See 1x to 10x Verification Movie (1438KB). The methodology here is to start of with an original pixel size image, which is 52 x 80 pixels, and progressively increase the scaling factor so that a 10x scaling occurs, in sequential increments.  The 1x scaling has a 1 second delay, and the 10x scaling has a 2 second delay, otherwise the delays are 0.5 seconds between frames. As can be seen from the GIF movie, feature rendition is accurate during scaling.

The 'Petaled Crater':

The parameters for the Sun Azimuth, North Azimuth, and Incidence Angle where taken from the IMG label as generated by NASAView.  The values are SUB_SOLAR_AZIMUTH = 208.964°, NORTH_AZIMUTH = 266.308°, and INCIDENCE_ANGLE = 57.758°.  Figure 3, following, is a 10x scaling done with GIMP using cubic spline interpolation.  It must be remembered that this is a relatively extreme scaling (10x), and therefore all noted features are at the extreme of resolution. There is no guarantee that the scaling has not introduced spurious details in the features.
10x cubic spline scaling of petaled 'crater' at (483, 2964) of THEMIS Image V01354003.Figure 3.
Starting with the left side of the petaled 'crater', we proceed alphabetically down the list of feature elements:

  1. The west most side of the crater should be in shadow, but is not, as shown by comparison with Crater 1 to the north of the main feature.  It is possible that if our main feature is a putative crater, then the inner wall slopes at less than a 32.242° angle from the horizontal.  However, this investigator does not believe so due to the signature of other details on that side of the 'crater', specifically the bright areas at the west through northerly directions (as indicated by the highlighting at (a)).  Shadows of up to 5 pixels in horizontal extent do indicate that on this side of the 'crater' there is a partial depression, or that the 'crater' lips rise above the central area by up to 54 m (176 ft).  Crater wall collapse presents certain shadowing dilemmas which are contrary to a crater depression presumption.
     
  2. The southeast side of the 'crater' wall shows indications of shadows on the outer rim. However, this area should be in light on the inside areas of the wall, as can be also seen via comparison to Crater 1.  This is opposite to what would occur if the feature were a 'crater'.  The possibility exists that this 'crater' has a raised lip, however, the raised lip must have a sharp outer edge, and this edge is not visible on the western side in (a).  This is visual ambiguity here, however, as the 'crater' appears to have lighted areas on the walls in a 360° sense. Regardless, photoclinometry shows that the feature here has shadow lengths of from four to six pixels, 43 m (141 ft) to 64 m (211 ft) high, with one section having a feature that has a shadow length that is eight pixels long, 86 m (281 ft) high.
     
  3. The southwest side of the 'crater' appears to have a downward going wash or slope feature that goes to the southwest.  The direction assumption results from the normal widening of talus or debris fields going from an upper source to a lower termination.  The widening gradient goes from inside to the outside of the 'crater'.  There also appears to be an outer circumference ring of material at this point, which indicates where the flat surface of the area outside of the main feature begins.  Details in this area indicate heights of up 21 m (70 ft), but averaging 11 m (35 ft) or less.
     
  4. Feature (d) appears to be a raised projection in the 'crater' central area.  The projecting discoloration (discussed in e.) that appears to focus on this feature is not a shadow, as it does not follow the projection of the sub-solar azimuth.  There is no significant shadow associated with this image, making its height less than 11 m (35 ft).
     
  5. The discolorations, which focus on the feature (d), appear to flow away from the feature and continue to the southeast.  There is an appearance of flow at the inner concentric ring, which would be the floor of the 'crater', to the south of feature (d).  The flow branches off into two separate 'runnels' which proceed in semi-radial fashion towards the outer circumference of the 'crater'.

Shape from Shading (Photoclinometry):

The author has developed a shape from shading plug-in for the GIMP 1.2.4 imaging application.  Using the shapefs plugin, the following 3D images where generated.  The source for the 3D renderings is Figure 3, above.

Note: Image needs regeneration, Figure 3A.

Note: Image needs regeneration, Figure 3B.

Frame 1 of GIF shapefs GIMP plug-in movie of feature on V01354003, rotating 360° on Z-Axis. Figure 3C (974KB).

As can be seen for the above three images (Figures 3A, 3B, and 3C), all three show height succinctly.  These 3D renderings support the arguments stated in the previous section with respect to a feature that actually rises above the surface, as opposed to the Crater 1 in Figure 3.  Figure 3C, just prev, links to a GIF movie (974KB) of the above feature, rotating 360° on the Z-Axis, with X-Axis angle = 25°, and Y-Axis angle = 50°.

Comparison to Splatter Crater:

For comparison, a splatter crater was located at (564, 2140) in V01354003ABR.IMG (3.76MB) at a distance of 827 pixels, 14.9 km (9.3 mi) to the north-northeast (5.69°) of the main feature.  Figure 4 has been processed from the original using the GIMP Image --> Colors --> Levels function to spread out the histogram and to lighten up the overall image.  Figure 5 is a 4x GIMP cubic spline interpolation of the feature in Figure 4.

Splatter crater at (564, 2140) in V01354003.IMG. 4x zoom of splatter crater at (564, 2140) in V01354003.IMG, showing sun and north azimuths.
Figure 4 Figure 5

Figure 5 shows a crater with a surrounding splatter signature.  As opposed to the main feature, Figure 1 and Figure 3, this crater example, though unusual, shows the classic signatures of a crater.  These signatures include shadowing on the same side as the sun location, lighted sides on the side opposite the sun location, a semicircular inner crater shadow, and lack of significant shadowing on the rim side farthest away from the sun location.  Photoclinometry shows that this is a relatively deep crater, with a rim wall to floor depth of 142 m (467 ft).  The crater wall gives a wall shadow of approximately 1 to 2 pixels, or a height of less than approximately 21 m (70 ft).  The splatters are approximately 261 m (856 ft) long with a standard sample deviation of 190 m (623 ft) and appear to leave the crater in a radial fashion.  The splatter heights are approximately the same as the crater wall height.  There is evidence of collapsing of the east through southeast crater wall.  This feature is visible on I01354002 at GIMP coordinates (178, 1117) on I01354002BTR.IMG.

Comparison to Other Features:

The other comparison feature is at (677, 2753) in V01354003ABR.IMG (3.76MB) at a distance of 288 pixels, 5.18 km (3.22 mi) to the northeast (42.6°) of the main feature.  Figure 6 has not been processed from the original other than conversion to GIF format from PDS IMQ format via NASAView.  Figure 7 is a 4x GIMP cubic spline interpolation of the feature in Figure 6.

Partially collapsed crater at (677, 2753) in V01354003.IMG. 4x zoom of crater at (677, 2753) in V01354003.IMG showing sun and north azimuths..
Figure 6 Figure 7

As can be seen, the shadow in this crater is relatively small in horizontal extent, indicating a shallower crater.  The shadow extent indicates a wall height of from 2 pixels to 7 pixels, 21 m (70 ft) to 75 m (246 ft).  It is apparent from close observation of the area under the sun azimuth indicator in Figure 7 that the area appears to have slumped down from the west crater wall in a southeasterly direction.  Crater wall heights appear to be 1 to 2 pixels, or 11 m (35 ft) to 21 m (70 ft).  Floor texturing is very similar to the surrounding area, possibly indicating an older crater that has probably been inundated with blowing debris.  This feature is visible on I01354002 at GIMP coordinates (198, 1213) on I01354002BTR.IMG.

Adjacent Mars Orbiter Camera(MOC) and THEMIS Images

MOC images that appear to be in the same general crater are at the following locations.  The center image coordinates for the feature discussed herein is 44.541°S, 151.122°W, using MOC coordinates.  This is as of the latest MOC Narrow Angle Gallery release at the time (March 11, 2003).
 

MOC Archive
/THEMIS Orbit
Designator/
Link
South 
Latitude
West Longitude
ab1_m04 M03-06164 44.89° 151.94°
e01_e06 E02-02169 44.71° 150.09°
1345 I01354002 45.583° 151.319°
2259 I02259016 44.631° 152.409°
1691 I01691003 46.642° 150.883°
1691 V01691004 44.402° 150.455°

Apparently Square Crater and 'Underground' Structures:

Crater 2 in Figure 3 shows a crater that is plainly square.  This is an example of where even as robust a scaling algorithm as GIMP's cubic spline interpolation fails where the original data is insufficient to allow for the required magnification.  Figures 1 and 2 show the unmagnified size of Crater 2.  This feature is approximately 25 pixels in area (5 x 5), and will not magnify correctly regardless of the scaling algorithm  used.  Figure 8 shows four examples of the different scaling algorithms in GIMP.  GIMP Zoom appears to be the same as GIMP Nearest Neighbor scaling.   Figure 9 gives similar examples for Adobe Photoshop.  Photoshop Zoom also appears to be the same as Photoshop Nearest Neighbor scaling.  The results of the scaling is very similar between GIMP and Photoshop, with slight textural differences between the two in cubic and linear modes.

Four GIMP scaling algorithim examples. Four Adobe Photoshop 7.0 scaling algorithim examples.
Figure 8 Figure 9

Similar effects result in the rectangular patterns visible in Figure 3 surrounding the main feature.  These rectangular patterns are NOT underground, surface, or artificial structures of any kind.  These are plainly features caused by processing of the image via a scaling algorithm.  In an attempt to perform beyond the resolution of the image itself, the scaling algorithms fill in with what would be mathematically correct for a certain pixel curve.  Mathematical correctness, however, does not imply physicality, and many independent investigators have fallen into this trap with Mars imagery.

Conclusion:

The petaled 'crater' in Mars Terra Sirenum shows evidence that it may actually not be a meteor crater.  Feature comparison with surrounding craters indicates that this 'crater' is strikingly different from any others in the area.  Shadow signatures do not match that of conic al section craters, being on the wrong side of the feature. One sector of the rim of the 'crater' shows a wash or slope that is consistent with a fall from the center outwards, instead of a fall from the rim inwards.  There are similarities with a nearby splatter crater, but there are significant differences between the two.

Due to the shadow signature of the petaled 'crater', its internal features, and it's rim structure, this 'crater' appears to be a raised feature instead of a depressed feature as a crater normally is. In the opinion of this investigator, morphological discrepancies with classic craters indicate similarities to certain features seen in the southern hemisphere of Mars, which appear to be fluid geysers, giving a concentric outer raised ring, and an interior plateau with a central orifice. Future revisions of this page will attempt to relocate the MOC image numbers for those other features so that morphological comparison may occur

These presumptive conclusions are refutable with MOC imagery of the 1.5 m caliber.

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