Perseverance rover finds strange green spots on Mars

NASA scientists still cannot understand what processes led to the appearance of unusual green spots on Martian rocks.

NASA’s Perseverance rover, which has been exploring Mars for four years in search of signs of past life, recently captured an interesting image in the abrasive zone of Malgosa Crest using its SHERLOC WATSON camera.

The photograph revealed black and white spots within the rock, along with surprising greenish areas. This unexpected discovery caught scientists’ attention, though the rock’s composition remains unidentified.

To examine the rock’s interior, Perseverance scraped off a small patch in an outcrop called Wallace Butte. This scraped area measured about 5 cm (2 inches) across, while the prominent green spot in the image is only about 2 mm (0.08 inches) across.

On Earth, red rocks like those on Mars get their hue from the oxidation of iron, which also colors human blood. Green spots on red rocks, similar to those seen by Perseverance, typically form when liquid water seeps through sediment, oxidizing iron and leaving green marks.

On Earth, microbes sometimes contribute to this process, but even without them, green spots can emerge through chemical interactions. For instance, reactions between sulfur and iron can facilitate iron reduction, creating green spots without microbial activity.

The exact reaction responsible for the green spots on Mars is still unknown. Unfortunately, Perseverance couldn’t safely extend its robotic arm to examine the spot in detail, as the area was too constrained.

NASA scientists hope that Perseverance will encounter similar spots in the future, allowing for a closer, more detailed investigation of these mysterious green markings.