NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA.
NASA Goddard Space Flight Center, Greenbelt, MD, USA.
Science. 2018 Jun 8;360(6393):1093-1096. doi: 10.1126/science.aaq0131.
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.
火星大气中甲烷含量的变化一直难以解释，部分原因是这些测量在时间和地点上不可重复。我们报告了好奇号火星车上的可调谐激光光谱仪在盖尔陨石坑进行的为期 5 年的原位测量结果。背景甲烷水平的平均值为 0.41 ± 0.16 体积分数（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）。这种变化大于表面撞击输送有机物的紫外线降解或年表面压力循环所预测的变化。背景的大幅季节性变化和更高临时峰值（约 7 ppbv）的出现与从火星表面或地下储层释放的甲烷的小局部源一致。
