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MER-B Dimes images
"mlm" wrote in message ... In 1 of the 3 DIMES images taken by Opportunity on its approach to the surface (at 1404m), there is a brightly ringed crater and a distinct, slightly diffuse dark circular shadow about half a crater width to its left. Is this the shadow of the spacecraft? I had thought the sunlight incidence angle was lower since it is supposed to be around 2PM local time at Meridiani. This seems to be directly below the spacecraft as it descends. So maybe it is something else. What do you make of the 2 bright parallel lines inside the crater? A 30 meter tall martian's sun-bed? Keith |
#12
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MER-B Dimes images
R Neutron wrote:
mlm wrote in message ... In 1 of the 3 DIMES images taken by Opportunity on its approach to the surface (at 1404m), there is a brightly ringed crater and a distinct, slightly diffuse dark circular shadow about half a crater width to its left. Is this the shadow of the spacecraft? I had thought the sunlight incidence angle was lower since it is supposed to be around 2PM local time at Meridiani. This seems to be directly below the spacecraft as it descends. So maybe it is something else. The 3 DIMES images are at: http://marsrovers.jpl.nasa.gov/galle...20040125b/MER- B_DIMES_1404m-B22R3.jpg http://marsrovers.jpl.nasa.gov/galle...20040125b/MER- B_DIMES_1690m-B22R3.jpg http://marsrovers.jpl.nasa.gov/galle...20040125b/MER- B_DIMES_1986m-B22R3.jpg Mark I think it is. Interestingly on the first of 3 DIMES in the lower right quadrant you can see a black dot/line. This looks suspiciously like the heatshield as seen on DIMES image from Spirit. Oh hell why not speculate even more. My bet is that it the lander is in one of the two craters down to the lower left of the larger crater that are side by next vertically in the image. There's not a lot more that I would call candidates. By the way I also think you can see a dimmer version of the shadow in the second DIMES image. RN If you make the simplifying assumption that the craft is falling on some straight path, shouldn't the movement of the shadow be along a line that intersects with the landing position? If so, you can draw a line between the faint shadow on the 1690m frame through the 1404 frame and see what small craters that line passes through. I see only one candidate within a reasonable distance. Of course, this geometry does not take bounce and roll into account. -- John Popelish |
#13
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MER-B Dimes images
"Keith Edkins" wrote in message ... "mlm" wrote in message ... In 1 of the 3 DIMES images taken by Opportunity on its approach to the surface (at 1404m), there is a brightly ringed crater and a distinct, slightly diffuse dark circular shadow about half a crater width to its left. Is this the shadow of the spacecraft? I had thought the sunlight incidence angle was lower since it is supposed to be around 2PM local time at Meridiani. This seems to be directly below the spacecraft as it descends. So maybe it is something else. What do you make of the 2 bright parallel lines inside the crater? A 30 meter tall martian's sun-bed? Keith Most likely sand dunes. |
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MER-B Dimes images
When these three Dimes images were first shown on the JPL press conference, Monday was it?, it was clearly stated from the rostrum that the dark dot surrounded by a bright halo, direct opposite to the Sun on the ground - WAS indeed the parachute! So, definitely no doubt about that... Regards, Bjørn Sørheim (Gordon D. Pusch) wrote: Highly unlikely, since this photo is almost certainly being taken from a quite high altitude, and your alleged "shadow" is a substantial fraction of the large crater's diameter --- whereas even the lander's parachute is quite small compared to the diameter of a typical aregraphical feature !!! Downloading the image and tweaking the image's intensity curve using the image editing tool 'xv' clearly brings out an ejecta blanket surrounding your dark spot, and gradations in intensity within said spot, that strongly suggest to me that your "shadow" is merely a deep, relatively "fresh" crater, and that the limited contrast range of a typical color monitor simply can't easily display the full dynamic contrast range in this image. Once this image has been processed a bit to "dodge out" the "over-exposed" crater rim and "burn in" the darker regions away from the main crater and within the dark, deep crater you've noticed, this picture will become MUCH more photogenic, and the nature of its various features quite obvious. -- Gordon D. Pusch perl -e '$_ = \n"; s/NO\.//; s/SPAM\.//; print;' -------------------------------------------------------- Anti-spam: Replace 'geo' with 'online' for direct e-mail -------------------------------------------------------- |
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MER-B Dimes images
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#17
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MER-B Dimes images
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