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The Perseverance landing site has now been named for Octavia E. Butler and from here there will be a meandering climb to get up on top of the "cliffs" that are in the delta.

I think that sediments there may be different than those on top of these "cliffs" and so this is a good thing.

But I'm surprised that the chosen ellipse straddles this feature basically 50:50, as if to say that before it or after it are both equally okay.

AAPG's Destination Jezero Crater: Landing Site of the Mars 2020 Perseverance Rover suggests the geology may be different on each side of these cliffs.

Question: Why Perseverance's landing ellipse straddled the cliffs in the river delta; why so ambivalent about the two different geologies?

Naively I would have expected it to be about 5 km to the right (East) to ensure the landing was in the lower area to ensure sampling of the lower geology, and to decrease chances of slamming into a cliff sideways if some aspects of the new terrain-sensitive landing implementation didn't go as planned.

If I had to guess, it would be that the ellipse was conservative and the folks at JPL had a pretty good idea just where they wanted to land, and nailed it. But that's just my own speculation for now.


This image shows two possible routes (blue and purple) to the delta

This image shows two possible routes (blue and purple) to the delta.

From CNN's Perseverance rover takes its first drive on Mars, sends back image

aapg.org: Main geologic units within Jezero crater shown on a basemap constructed from images from the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter (MRO)

Figure 3: Main geologic units within Jezero crater shown on a basemap constructed from images from the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter (MRO). Blue circle shows the location of the Perseverance rover landing ellipse.

From Destination Jezero Crater: Landing Site of the Mars 2020 Perseverance Rover


More images, from How tall are the "cliffs of the delta" in the Perseverance rover's landing ellipse? Click for larger.

Perseverance Rover 7x7 x 6.6 km Landing Ellipse in Jezero Crater Cropped from PIA24483

left: full image source and more right: Cropped from PIA24483

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  • $\begingroup$ I have found this disembodied image (can't remember where I found it) astrogeology.usgs.gov/cache/images/… it might be helpful, and now just found these USGS pages: Jezero crater Mars 2020 landing area (almost the same image) and Jezero Crater on Mars Geologic Map Detail $\endgroup$ – uhoh Mar 7 at 1:07
  • $\begingroup$ I'm surprised that the chosen landing ellipse includes so much rough looking country on the western delta, but that aside, I suggest the eventual landing site gives two distinct geological types for Perseverance to check out which in turn gives info on the veracity of HiRISE findings $\endgroup$ – giles tester Mar 7 at 8:30
  • $\begingroup$ @gilestester by "both" do you think that if it landed in the west side of the ellipse it would have first gone east (and down in elevation) to check out the lower area? My thinking (rightly or wrongly) is that that would never happen; that they'd never go backwards, so the only chance of seeing the lower stuff would be to ensure it landed in the lower stuff. That thinking could certainly be totally wrong, it's simply implicit in my question. $\endgroup$ – uhoh Mar 7 at 9:22
  • $\begingroup$ In the end it was the TRN that chose the exact landing spot (give or take 40m) based on geographical considerations rather than geological factors $\endgroup$ – giles tester Mar 7 at 9:59

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