How the Curiosity Rover Revealed Mars Was Once Habitable

NASA's Curiosity Mars rover has passed 5,000 Martian days on Mars. Explore what it found, from ancient lakes to organic molecules. The evidence shows that ancient Gale Crater had conditions that could support microbial life. Curiosity has not found life. 0:00 A grey powder on Mars 0:35 Landing in Gale Crater 1:39 The first yes: water and chemistry 3:16 A lake that lasted, and mud cracks 4:35 Radiation, organics, methane and oxygen 7:10 Sulfur, Gediz Vallis, big organics, siderite 8:34 What habitable does not mean 9:06 5,000 Martian days 10:45 The question What is known: in March 2013 NASA reported that the first rock Curiosity drilled ("John Klein") held the key chemical ingredients for life, clay minerals and an energy gradient microbes could use: an environment that could have supported microbes. Later work found long-lived lakes (3.8–3.3 billion years ago), mud cracks recording repeated wet–dry cycles, ancient organic molecules, seasonal methane and oxygen, pure sulfur and siderite. What is not known: whether life ever existed there. Curiosity has not found life or fossils, the source of the methane is unknown, and how much methane there is remains disputed. Sources NASA/JPL: "NASA Rover Finds Conditions Once Suited for Ancient Life on Mars" (12 Mar 2013); "NASA Rover Finds Old Streambed on Martian Surface" (27 Sep 2012) Grotzinger et al., Science (2015), via Caltech; Eigenbrode et al. & Webster et al., Science (8 Jun 2018) Rapin et al., Nature (2023) — mud cracks; Hassler et al., Science (2013) — surface radiation; Farley et al., Science (2014) — exposure age ESA ExoMars Trace Gas Orbiter methane results (2019); NASA/JPL day–night methane study (2021); NASA Goddard oxygen study (Nov 2019) NASA/JPL: sulfur crystals and Gediz Vallis (2024); largest organic molecules, PNAS (Mar 2025); siderite, Science (17 Apr 2025) NASA Photojournal: Curiosity postcard for sol 5000 (PIA26700, 16 Sep 2026); boxwork and 1 km elevation updates (2026) Visuals: NASA/JPL-Caltech/MSSS (Mastcam, MAHLI, MARDI); NASA/JPL-Caltech (Navcam, Hazcam; sky crane artist concept); HiRISE NASA/JPL-Caltech/Univ. of Arizona; NASA Goddard Space Flight Center and Scientific Visualization Studio. Animations, artist concepts, graphics and artistically coloured postcards are labelled on screen. Narration is a synthetic voice. Independent production, not affiliated with or endorsed by NASA or JPL. If you could bring one Mars rock home, which would it be: the ancient lake mudstone, or rock from the groundwater ridges? Tell us why in the comments.