The uncertainty of science: Last week, while I was flying to Israel, the Opportunity science team announced the discovery of strange aligned erosion lines, what they are calling stone stripes, in Perseverance Valley.

The ground texture seen in recent images from the rover resembles a smudged version of very distinctive stone stripes on some mountain slopes on Earth that result from repeated cycles of freezing and thawing of wet soil. But it might also be due to wind, downhill transport, other processes or a combination.

…On some slopes within the valley, the soil and gravel particles appear to have become organized into narrow rows or corrugations, parallel to the slope, alternating between rows with more gravel and rows with less.

The origin of the whole valley is uncertain. Rover-team scientists are analyzing various clues that suggest actions of water, wind or ice. They are also considering a range of possible explanations for the stripes, and remain uncertain about whether this texture results from processes of relatively modern Mars or a much older Mars.

For those who are regular readers of Behind the Black, you already knew about a variation of this discovery back in November 2017, from my regular rover updates. Then, they discovered aligned groves in the gravel that looked to me like slickensides, erosion patterns produced by glacial activity. The science team told me, however, that they were favoring wind, not ice, as a primary cause, though that conclusion was far from certain.

In the press release last week, they focused more on the aligned erosion patterns in the fine gravel that appear to align perpendicular to the slope. Though they think they have found a comparable Earth-based phenomenon that might explain these patterns, it appears that the science team remains just as unsure of their cause as they are for the rocks.