NASA's Perseverance Mars Rover

Paul, let me thank you again for all that you do to keep this community going. I know this question is kind of detailed, but I'd be happy if you could steer me even a little here.

I have some confused impressions about Ingenuity's last several flights. I seem to remember the flight team (or someone at JPL) mentioning that the drone's navigation software was having trouble orienting itself above mega-ripples and ripple fields, like the one occupying the Neretva channel, though Ginny had crossed plenty of ripple fields elsewhere in Jezero. If those fields were that disorienting, why was the team determined to fly the drone along that terrain, rather than directly across? (You can see that in flights 68-70, they didn't take the short way across the ripples, as they did in flights 36-40!) Some stretches of the Neretva channel do have steep sides, admittedly, especially as one moves in the upstream direction. I can imagine that they wanted Ginny to avoid that sloping terrain - well and good; why not follow the edge of the upper fan, then, alongside the channel, as Percy did? I do remember that the terrain was very blocky, and that it was slow going for the rover, but Ginny had navigated such terrain before itself, simply keeping up with the rover. They could have flown Ginny across the same relatively narrow and unrippled reach of Neretva that the rover took on the way to Bright Angel.

For me, the irony of Ingenuity's loss is that it did not occur in flying over all the variegated terrain of the crater floor - confusing even to geologists - or the steep cliffs of the delta front, or the weird surface of the upper fan... but in a ripple field. On a vertical hop, no less, when no lateral motion was planned. Geoscience me thinks, probably naïvely, that moderately-sized ripple fields like the one in Neretva are among the most organized and benign terrains the landscape offers in this part of Mars. They're not featureless like the smooth slopes of the crater rim - ripple crests are readily identifiable in Ginny NavCam images as sequential, distinct and curvilinear, forming high-contrast boundaries in most, if not all, cases. So you... land between them, where slopes are gentlest (and the drone didn't even seem to need the flattest slopes available!) I'm not a coder or engineer by any means, and I'm not trying to say that any of this is easy, but... if ripple fields are disorienting to the point where you must fly over them high and fast, shouldn't we have avoided them as much as possible?