Mars holds organic matter on its surface, indicating a history of abundant water flow. Curiosity rover found organic sediments in Gale Crater with unusually low 13C isotope abundance compared to Earth.

These findings suggest Martian organic matter significantly differs from terrestrial and meteoritic origins. Laboratory experiments showed that Martian atmospheric conditions could cause isotopic fractionation, affecting carbon isotopes. Simulated conditions matched organic matter compositions found on Mars, suggesting atmospheric processes shaped early Martian organics."