Global — detected at Phoenix landing site (68°N), Gale Crater (Curiosity), Jezero Crater (Perseverance)
Estimated Quantity
0.5–1% perchlorate by weight in near-surface soil
Phoenix WCL wet chemistry; Curiosity SAM; consistent globally
As of 2021-01-01
Perchlorates were first confirmed by the Phoenix wet chemistry lab in 2008. Their presence globally explains why Viking's biology experiments gave confusing results — perchlorates oxidize organic molecules when heated. At 0.5-1% concentration they are present in every Martian soil sample analyzed. This discovery fundamentally changed our understanding of Martian surface chemistry and has major implications for habitability and future crewed surface operations.
Ammonium perchlorate is a solid rocket oxidizer — in theory Martian perchlorates could be chemically processed into propellant components; also possible source of oxygen via thermal decomposition
Reality Check
Perchlorates are highly toxic to humans and other organisms — a major challenge for habitability and agriculture. Must be removed from any soil used for growing food
Confidence: high · Last verified 2026-06-01
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