Since landing at Gale crater, Mars, in August 2012, the Curiosity rover has searched for evidence of past habitability, such as organic compounds, which have proved elusive to previous missions. We report results from pyrolysis experiments by Curiosity’s Sample Analysis at Mars (SAM) instrument, focusing on the isotopic compositions of evolved CO₂ and O₂, which provide clues to the identities and origins of carbon- and oxygen-bearing phases in surface materials. We find that O₂ is enriched in ¹⁸O (δ¹⁸O about 40‰). Its behaviour reflects the presence of oxychlorine compounds at the Martian surface, common to aeolian and sedimentary deposits. Peak temperatures and isotope ratios (δ¹⁸O from −61 ± 4‰ to 64 ± 7‰; δ¹³C from –25 ± 20‰ to 56 ± 11‰) of evolved CO₂ indicate the presence of carbon in multiple phases. We suggest that some organic compounds reflect exogenous input from meteorites and interplanetary dust, while others could derive from in situ formation processes on Mars, such as abiotic photosynthesis or electrochemical reduction of CO₂. The observed carbonate abundances could reflect a sink for about 425–640 millibar of atmospheric CO₂, while an additional 100–170 millibar could be stored in oxalates formed at the surface. In addition, oxygen isotope ratios of putative carbonates suggest the possibility of widespread cryogenic carbonate formation during a previous era.

自 2012 年 8 月降落在火星盖尔陨石坑以来，好奇号火星车一直在寻找过去可居住性的证据，例如有机化合物，这在以前的任务中被证明是难以捉摸的。_{我们报告了好奇号火星样品分析 (SAM) 仪器的热解实验结果，重点关注演化出的 CO 2}和 O ₂的同位素组成，这为表面材料中含碳和含氧相的特性和起源提供了线索。我们发现O ₂富含¹⁸ O（δ ¹⁸ O约40‰）。它的行为反映了火星表面存在的氧氯化合物，常见于风成沉积物和沉积沉积物。峰值温度和同位素比 (δ ¹⁸O 从 -61 ± 4‰ 到 64 ± 7‰；_{产生的CO 2}的δ ¹³ C（从–25 ± 20‰ 到56 ± 11‰）表明存在多相碳。我们认为一些有机化合物反映了来自陨石和行星际尘埃的外源输入，而另一些则可能来自火星上的原位形成过程，例如非生物光合作用或 CO ₂的电化学还原。观测到的碳酸盐丰度可以反映大气 CO ₂约 425-640 毫巴的汇，而额外的 100-170 毫巴可以储存在地表形成的草酸盐中。此外，推定碳酸盐的氧同位素比率表明在前一个时代可能广泛形成低温碳酸盐。