Behind The Black – Robert Zimmerman

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Cool image time! The photo to the right, cropped, reduced, and enhanced to post here, was taken on August 17, 2022 by one of Perseverance’s high resolution camera. It shows the exposed layers of a nearby cliff face that comprises the end of the delta that once flowed into Jezero Crater in the distant Martian past.

My guess is that this cliff is about 20 feet high. The more massive, thicker and younger layers near the top, compared to the thinner and older layers below, suggest a major change in the cyclic events. The early cycles that lay down this delta were initially shorter and able to place less material with each cycle, while the last few cycles were longer, producing thicker layers.

The difference in layers also strongly suggests that all the blocks at the foot of the cliff fell from more massive layers at the top. Material that broke off from the lower thinner layers has likely long ago eroded away.

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Since August 5th, the Perseverance science team has been trying to figure out the origin as well as the consequences of “two string-like pieces” of foreign object debris (FOD as used by today’s acronym-happy scientists) that they have spotted next to one of the rover’s coring drill bits.

The photo to the right, cropped and reduced to post here, looks directly down at that core drill bit and shows one of those strings both to the side of the bit as well in full resolution in the inset. From today’s update:

Since first identified Aug. 5 in imagery of the rover’s sample collection system after a 12th rock core sample was taken, the FOD has been the focus of several methodical diagnostic activities in an attempt to better understand the nature of the debris.

We’ve commanded the rover to move, rotate, or vibrate components we think could harbor FOD. And we’ve obtained multiple sets of images of the components from different angles and in different lighting conditions from rover cameras: Mastcam-Z, Navcam, Hazcam, Supercam, and even the WATSON (Wide Angle Topographic Sensor for Operations and eNgineering) camera located on the rover’s turret. Finally, a thorough review of recent coring and bit-exchange activities confirm that they all executed nominally with no indication of interference from the FOD.

Analysis of the latest round of imaging, downlinked earlier today, indicates that while the two small pieces remain visible in the upper part of the drill chuck, no new FOD has been observed. In addition, imagery taken of the ground beneath the robotic arm and turret, as well as the rover deck, also showed no new FOD.

Because these strings do not appear to interfere in any way with the drill’s operation, the science team has decided neither is a cause for concern, and will therefore command the rover to leave this just-completed drill site and move on to the southwest to a location at the base of the delta the rover visited about three months ago.

The strings themselves are likely pieces from the equipment released during the rover’s landing, and might even have come from the tangled string the rover imaged on the nearby ground in July, and that was gone just four days later. The wind had blown it away, and may have even at that time blown pieces into the drill.