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Today’s cool image illustrates that Mars is not merely the Red Planet, but actually does have places on its surface that are colorful and interesting. The picture to the right, cropped and reduced to post here, was today’s picture of the day for the high resolution camera on Mars Reconnaissance Orbiter (MRO). As Alfred McEwen of the Lunar & Planetary Laboratory in Arizona notes in the caption:
This region of Mars has a diversity of minerals resulting in especially colorful images. However, the geology is complex and not easy to understand. Nili Fossae has often been on the list for potential landing sites for robotic exploration, and will likely continue to be so given its rich landscape.
When I asked McEwen what minerals are indicated by the different colors, he responded that at the scale provided by MRO, the reddish colors indicated dust or water-altered minerals like clays, and the blue/green colors indicated mafic minerals like pyroxene and olivine.
You can get a sense of the scale by looking at the wider image below. The overview map below that provides some interesting context, including a hint as to why Perseverance landed where it did.
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The photo to the right, cropped, reduced, and annotated to post here, was taken on January 17, 2022 by MRO’s high resolution camera. The white rectangle marks the area covered by the picture above. The colors are not exactly the same because the image to the right has not been processed as completely as the image above.
The terrain here is complex and somewhat baffling. The location, indicated by the black dot in the overview map, is just to the east of a large 30-mile-wide unnamed old and very eroded crater, and likely includes in the full image the rims of two even more obscure smaller craters to the north and south. Thus, much of what we see in this image is likely ejecta from those craters, reworked significantly in the eons since impact.
This colorful terrain, about 250 miles west of Jezero Crater where Perseverance and Ingenuity are roaming, shows us a small part of the reason why that crater was picked. This region, dubbed Nili Fossae, extends east to much closer to Jezero. In fact, I suspect, based on many MRO images I’ve looked at, that once Perseverance finishes exploring the delta that flowed into the crater and moves west through the gap in the crater rim up onto the cratered highlands beyond, it will be moving into similar geology as shown in this picture, geology that all evidence suggests is rich in useful minerals. As I noted in a post about Nili Fossae in March 2021:
… the wide variety of minerals already located in Nili Fossae marks this as a place that future settlers are going to want to visit very early in their explorations. Not only may it contain valuable materials needed by them, it is relatively close to the glacier country to the northwest, where there is a lot of very accessible ice.