Behind The Black – Robert Zimmerman

Click for the Sol 4518 original image.

In a set of new pictures taken of Curiosity’s wheels yesterday it appears that the damage to those wheels has increased significantly in the past year, with the most damaged wheel (which based on contradictory science team reports is either the middle left or middle right wheel), having more had more sections broken to the point where this wheel might even fail in the near future.

The pictures to the right show these changes. The treads, called grousers, have been numbered to make the comparisons easier. The bottom two pictures were taken in September 2024, and look at this wheel with the damage on the side to show how a whole section of the wheel had at that time collapsed to form a depression.

The top two pictures show the increase in the damage in this section between February 2024 and yesterday. Note especially the changes in growlers 4, 5, and 6. Not only have large sections broken off in the wheel’s central section, it appears that the wheel’s outside section is beginning to separate from that central section.

The increased damage in the past year illustrated starkly the roughness of the terrain that the rover is traversing. Moreover, there is no sign that roughness is going to ease anytime in the near future. This increased damage thus explains partly why the science team changed the rover’s route to get to the nearby boxwork geology as fast as possible. That unique geology is likely to provide some important scientific information unobtainable elsewhere, and it seems worthwhile to get to it before this particular wheel fails.

There is one silver lining to this cloud. This particular wheel is a middle wheel, which means it is less critical to maintaining the rover’s stability as it travels as well as sits. The photographs of the other wheels taken today do not show as much change. Even if this wheel fails, the rover will still have five working wheels, including the most essential four corner wheels.

The uncertainty of science: Scientists studying four different core samples drilled by the Mars rover Curiosity have detected abundant amounts of the iron carbonate mineral siderite, suggesting that there is more carbon within Mars’ crust than previously believed.

If that quantity of carbon is confirmed, there might also have been a carbon cycle between Mars’s atmosphere and the liquid water theorized to have once been on the surface. This cycle could also have made the atmosphere both thicker and warmer, conditions necessary for that liquid water to exist on the surface. From the research paper:

[D]ecomposition of siderite occurred in multiple locations and released CO2 into the atmosphere, recycling CO2 that was originally sequestered during siderite formation. Diagenetic carbonate destruction observed elsewhere on Mars, in martian meteorites, and in sandstones on Earth yields nearly identical reaction products to those we found in Gale crater and are observed globally in orbital data. We therefore conclude that in situ, orbital, and terrestrial analog evidence all indicate that postdepositional alteration of siderite closed the loop in Mars’ carbon cycle, by returning CO2 to the atmosphere.

The uncertainties here are gigantic. For these conclusions to be right, the scientists extrapolate without evidence the same amount of CO2 found in these four cores as existing across the entire surface of Mars. That is a very big extrapolation that no one should take very seriously.

Furthermore, this research assumes the geological features we see on Mars were formed from liquid water. More recent orbital data suggests glacial and ice processes might have played a part instead, with one study concluding that Gale Crater was never warm enough for long-standing liquid water, and that ice and glacial processes must have played the larger part in forming what we find there.

The data from these core samples however is intriguing for sure, though it mostly raises more questions about Mars’ past geological history than it answers.