The Green Spot That Could Have Changed History: NASA Leaves Behind Its Best Clue to Past Life on Mars

A small greenish spot discovered on Mars by the Perseverance rover has sparked scientists’ curiosity. It may be the most significant indication of past life that NASA has found on the Red Planet, second only to the leopard-spot pattern seen at Cheyava Falls in July. However, the rover hasn’t yet been able to analyze it.

A green spot. NASA announced the discovery on Oct. 25. However, the space agency first captured the green spot in a nighttime image taken on Aug. 19, in the Mars region known as Serpentine Rapids, located in the bed of Jezero Crater.

This intriguing greenish stain, which measures barely 0.08 inch in diameter, was discovered after NASA’s rover used an abrasion tool to scrape off a rock nicknamed Wallace Butte. The process revealed a surprising array of colors, including the greenish stain.

Among red rocks. Captured by Perseverance’s SHERLOC WATSON camera on the tip of its robotic arm, the image reveals a notable feature. A characteristic green spot with a dark core and fuzzy outline stands out against the reddish background. The red color of these rocks is due to the presence of rusty iron.

Here’s where it gets intriguing. On Earth, red rocks or beds can develop green spots when oxidized iron undergoes a chemical reduction, typically in the presence of liquid water. This iron reduction on our planet can be linked to microbial activity or decaying organic matter. However, it can also happen without any biological involvement through chemical interactions with sulfur.

Biological aspect. Although NASA scientists advise caution, the existence of this anomaly on Martian soil could suggest that life once existed on the Red Planet. In fact, these green spots might be one of the first tangible signs of past life on Mars.

Alternatively, it’s possible that the green stain is the result of ancient interactions between minerals in the soil and water in Jezero Crater, which once contained a lake, without any involvement from living microorganisms.

A missed opportunity. Due to the terrain’s complexity, the rover couldn’t position its sophisticated chemical analysis instruments directly over the green spot. As a result, the composition of the stain remains a mystery.

However, there’s hope that Perseverance will find better opportunities at its targeted sites. The rover continues its ascent along Jezero Crater’s rim, navigating through steep and challenging terrain to reach Pico Turquino and Witch Hazel Hill. These locations are considered some of the most promising for investigating ancient hydrothermal activity and stratified rocks. The search for evidence of past life continues, and hope isn’t lost.

Image | NASA-JPL

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