Measuring martian organics and methane The Curiosity rover has been sampling on Mars for the past 5 years (see the Perspective by ten Kate). Eigenbrode et al. used two instruments in the SAM (Sample Analysis at Mars) suite to catch traces of complex organics preserved in 3-billion-year-old sediments. Heating the sediments released an array of organics and volatiles reminiscent of organic-rich sedimentary rock found on Earth. Most methane on Earth is produced by biological sources, but numerous abiotic processes have been proposed to explain martian methane. Webster et al. report atmospheric measurements of methane covering 3 martian years and found that the background level varies with the local seasons. The seasonal variation provides an important clue for determining the origin of martian methane. Science, this issue p. 1096, p. 1093; see also p. 1068 The background level of methane in Mars’ atmosphere varies with season, providing a clue to its origin. Variable levels of methane in the martian atmosphere have eluded explanation partly because the measurements are not repeatable in time or location. We report in situ measurements at Gale crater made over a 5-year period by the Tunable Laser Spectrometer on the Curiosity rover. The background levels of methane have a mean value 0.41 ± 0.16 parts per billion by volume (ppbv) (95% confidence interval) and exhibit a strong, repeatable seasonal variation (0.24 to 0.65 ppbv). This variation is greater than that predicted from either ultraviolet degradation of impact-delivered organics on the surface or from the annual surface pressure cycle. The large seasonal variation in the background and occurrences of higher temporary spikes (~7 ppbv) are consistent with small localized sources of methane released from martian surface or subsurface reservoirs.

中文翻译：

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火星大气中甲烷的背景水平显示出强烈的季节性变化

测量火星有机物和甲烷 好奇号火星车过去 5 年一直在火星上采样（参见 10 位凯特的观点）。艾根布罗德等人。使用 SAM（火星样品分析）套件中的两台仪器捕捉保存在 30 亿年前沉积物中的复杂有机物的痕迹。加热沉积物会释放出一系列有机物和挥发物，让人想起地球上发现的富含有机物的沉积岩。地球上的大多数甲烷是由生物来源产生的，但已经提出了许多非生物过程来解释火星甲烷。韦伯斯特等人。报告对火星 3 年的甲烷进行大气测量，发现背景水平随当地季节变化。季节性变化为确定火星甲烷的来源提供了重要线索。科学，这个问题 p。1096 页。1093; 另见第。1068 火星大气中甲烷的背景水平随季节变化，提供了其起源的线索。火星大气中不同水平的甲烷无法解释，部分原因是测量结果在时间或地点上不可重复。我们报告了好奇号火星车上的可调谐激光光谱仪在 5 年内对盖尔陨石坑进行的原位测量。甲烷的背景水平的平均值为十亿分之 0.41 ± 0.16 体积 (ppbv)（95% 置信区间），并表现出强烈的、可重复的季节性变化（0.24 至 0.65 ppbv）。这种变化大于根据地表撞击产生的有机物的紫外线降解或每年地表压力循环预测的变化。