Case file LinkedIn Crossclimb #852: 5-letter ladder, 5 middle exhibits, combo prompt "What NASA's Perseverance is, and what it photographed from Mars on October 4, 2025.". Endpoints: ROVER (top) and COMET (bottom).
Middle phase answers: "Mississippi or Nile, for example" = RIVER; "Scuba ___" = DIVER; "City in England with white cliffs" = DOVER; "Perform a new version of a song originally by another artist" = COVER; "Have a strong desire for something that belongs to someone else" = COVET.
Ordering phase: the valid middle chain is RIVER → DIVER → DOVER → COVER → COVET. This permutation is the only valid one-letter chain for these answers.
Evidence link: ROVER → RIVER. O→I at the second letter (ROVER → RIVER).
Evidence link: RIVER → DIVER. R→D at the first letter (RIVER → DIVER).
Evidence link: DIVER → DOVER. I→O at the second letter (DIVER → DOVER).
Evidence link: DOVER → COVER. D→C at the first letter (DOVER → COVER).
Evidence link: COVER → COVET. R→T at the fifth letter (COVER → COVET).
Evidence link: COVET → COMET. V→M at the third letter (COVET → COMET).
Verdict: ROVER → RIVER → DIVER → DOVER → COVER → COVET → COMET satisfies every one-letter constraint. The combo clue "What NASA's Perseverance is, and what it photographed from Mars on October 4, 2025." describes both end words together — "ROVER" and "COMET" each differ by one letter from their adjacent middle rungs and satisfy the shared top+bottom prompt.