On 18 February 2021, NASA’s Mars 2020 Perseverance rover touched down in Jezero crater, a site chosen for its ancient lakebed and delta deposits. Following a 100-sol commissioning phase and the Ingenuity helicopter’s historic flight demonstrations, the rover began its first science campaign: a detailed exploration of the crater floor. This terrain, marked by t he Máaz and Séítah formations, had long puzzled scientists due to uncertainty over whether its rocks were igneous or sedimentary.
The campaign, spanning sols 100–379, was meticulously planned to investigate the geology, search for signs of past habitability, and collect samples for eventual return to Earth. Perseverance traversed over 5 km, conducted seven abrasion studies, and sealed nine sample tubes, including four paired rock samples from distinct lithologies.
The Máaz formation, widespread across the crater floor, is mafic and crater-retaining. Fieldwork revealed five members: Naa’táanii, Ch’ał, Rochette, Artuby, and Roubion. Upper Máaz members (Naa’táanii and Ch’ał) are more evolved basaltic to basaltic andesite, with Ch’ał being the hardest and least altered rock encountered. Lower Máaz members (Artuby and Rochette) are less evolved, pyroxene-rich basalts, often layered or pitted. Roubion’s stratigraphic position remains debated, showing similarities to both upper and lower members.
The Séítah formation underlies Máaz and is dominated by the Bastide member, an olivine-rich cumulate with coarse crystals formed from slow cooling and differentiation of a large magma body. Layering is common but difficult to trace between outcrops. A second member, Content, is notable for lacking olivine and having evolved compositions similar to upper Máaz, suggesting possible correlation.
Proximity science on abraded patches confirmed both formations are igneous. Séítah’s olivine grains are often rimmed by carbonate, indicating aqueous alteration. Máaz rocks contain Fe/Mg phyllosilicates and less frequent carbonates. Multiple episodes of alteration produced sulfates, halite, perchlorate, and amorphous silicates, likely from fluids of varying chemistry. Purple-toned surface coatings, hydrated and dust-like in composition, suggest cementation by fluids.
A key structural finding was that rocks near the Máaz–Séítah contact at Artuby ridge are tilted 10–15° southwest, seen in both surface imaging and RIMFAX subsurface profiles. This tilt implies post-emplacement deformation, though the mechanism remains uncertain. Erosion has since sculpted the present-day textures, liberated olivine grains from Séítah, and redistributed them into Máaz regolith.
Sampling milestones included Rochette (Rochette member, lower Máaz), Ch’ał (upper Máaz), Brac and Issole (Bastide member, Séítah). Rochette cores were targeted for their competence after a failed attempt at Roubion. Ch’ał samples aim to constrain crater chronology. Brac and Issole represent different stratigraphic intervals of Séítah, both rich in olivine and carbonate.
SHERLOC’s fluorescence and Raman spectroscopy detected signals consistent with aromatic organics in both formations, often associated with sulfate-rich domains. While Raman confirmation was rare, fluorescence peaks around 270–285 nm and 338–350 nm suggest possible organic molecules, though mineral luminescence cannot be ruled out.
Atmospheric monitoring throughout the campaign revealed Jezero as an active aeolian environment. MEDA sensors, Mastcam-Z, Navcam, and the SuperCam microphone documented dust devils, gust lifting events, and migrating megaripples. Observations during a regional dust storm provided rare data from within a dust source region.
By campaign’s end, Perseverance had achieved its primary objectives: defining the geology and origin of the crater floor units, characterizing alteration processes, documenting atmospheric and surface dynamics, and collecting a diverse sample suite. The mission resolved the long-standing debate over igneous versus sedimentary origins, with Máaz as a series of lava flows and Séítah as an olivine cumulate. Returned samples will refine age models, petrogenesis, and habitability assessments, deepening understanding of Jezero’s geologic history.