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- A rover on Mars found some red rocks with green spots<\/strong>. The intriguing spots are dark in the middle with fuzzy green rims. The rocks are in the same ancient river valley where other unusual rocks were found.<\/li>\n
- The rocky green spots are similar to those seen on Earth<\/strong>. They might be formed by chemical reactions with water that create reduced iron. The exact process isn\u2019t known yet, but on Earth it sometimes involves microbes.<\/li>\n
- Mission scientists are on the lookout for similar rocks<\/strong>. So, what will the rover find next?<\/li>\n<\/ul>\n
The 2025 EarthSky Lunar Calendar presale is here! The first 100 people to order get a signed copy by the legendary Deborah Byrd as a thank you! Go to The EarthSky Store to secure yours today!<\/p>\n
Intriguing green spots in rocks on Mars<\/h3>\n
As NASA\u2019s Perseverance rover has been making its way from the floor of Jezero crater up to its rim, it keeps finding unusual rocks. These include the leopard spots and zebra rocks. On October 25, 2024, NASA provided an update on some other intriguing rocks: distinctly red rocks with green spots. The rover found them at a location called Serpentine Rapids, within the ancient river valley Neretva Vallis. NASA said the spots were just under the surface of the rocks and are dark in the middle with fuzzy, green rims. They likely formed when liquid water altered oxidized iron. On Earth, this process sometimes involves microbes. But what about Mars?<\/p>\n
Green spots in rocks on Mars<\/h3>\n
Perseverance discovered the rocks at a location called Serpentine Rapids. It is within the ancient river valley called Neretva Vallis, which cuts through the rim of Jezero crater. The riverbed ends in a branching delta that is still clearly visible today. The rover came across the rocks about 20 sols (Martian days) after it finished studying the \u201cleopard spots\u201d rocks at Bright Angel, also in the river valley.<\/p>\n
Most rocks on Mars appear reddish on their surfaces, due to oxidation and reddish dust \u2013 which is everywhere<\/em> \u2013 coating them. But Perseverance spotted some rocks at Serpentine Rapids that were even more distinctly red in color. The rover used the abrading bit on its drill to create a small circular patch on one of the rocks, named Wallace Butte. This revealed what the rock looked like just under the surface. White, black and green colors could be seen.<\/p>\n
Interestingly, the abrasion patch also showed something surprising: small roundish and oblong dark spots with fuzzy, green rims. What were they?<\/p>\n
Evidence of past liquid water \u2026 and perhaps life?<\/h3>\n
The spots look similar to spots in red rocks on Earth. Scientists call those rocks red beds. The red color comes from oxidized iron, the same found in our blood or rusted metal. And, indeed, green spots are also often found in these rocks. They form when liquid water percolates through sediments. Later, those sediments harden into rock. Consequently, this causes a chemical reaction that changes the iron into a reduced form with a greenish hue.<\/p>\n
There are various specific ways this can happen. First, sulfur and iron can interact to create the conditions for the reduced iron to occur. Or, decaying organic matter can also produce a similar result. And \u2013 at least on Earth \u2013 microbes can also help facilitate the process.<\/p>\n
We don\u2019t know which of these scenarios explains the Martian green spots. It is tempting, of course, to think the green color must be a sign of life, but it can occur through other chemical reactions as well.<\/p>\n
![\"Roundish](\"https:\/\/earthsky.org\/upl\/2024\/10\/green-spots-Serpentine-Rapids-Perseverance-rover-Mars-natural-color-August-15-2024.png\")
View larger. | A more natural color view of the spots from the top image, seen by Perseverance on August 15, 2024. Image via NASA\/ JPL-Caltech.<\/figcaption><\/figure>\n ![\"Brownish-reddish](\"https:\/\/earthsky.org\/upl\/2024\/10\/green-spots-Serpentine-Rapids-Perseverance-rover-Mars-August-19-2024.jpg\")
View larger. | Another view of some of the green spots. This is a nighttime image, with illumination from the rover. The diameter of the abrasion patch \u2013 the circular area \u2013 is 5 centimeters (2 inches). The large green spot in the upper left of the image is about 2 millimeters (0.08 inch) in diameter. Perseverance took this image on August 19, 2024. Image via NASA\/ JPL-Caltech.<\/figcaption><\/figure>\n Looking for more red and green rocks<\/h3>\n
Unfortunately, Perseverance wasn\u2019t able to conduct a more in-depth analysis of the spots. As NASA explained it, there wasn\u2019t enough room to place the rover arm directly on top of the tiny spots. That arm contains the SHERLOC and PIXL instruments needed to do the analysis. The rover did zap them with its laser, however, which is part of SHERLOC. The laser looks for organic material and minerals altered by water.<\/p>\n
So now the mission team is on the lookout for other similar rocks. The rover is ascending the steep wall of Jezero crater and will ultimately leave the crater. What will it find next?<\/p>\n
Bottom line: NASA\u2019s Perseverance rover has found some intriguing green spots in rocks on Mars. The spots are dark in the middle with fuzzy, green rims. How did they form?<\/p>\n
Via NASA<\/p>\n
Read more: Ancient life on Mars? Rover finds intriguing \u2018leopard spots\u2019<\/p>\n
Read more: A striped \u2018zebra rock\u2019 on Mars and a new Mars face<\/p>\n
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\n - The rocky green spots are similar to those seen on Earth<\/strong>. They might be formed by chemical reactions with water that create reduced iron. The exact process isn\u2019t known yet, but on Earth it sometimes involves microbes.<\/li>\n