Seismic Detection of the Martian Core by InSight

We report on the detection of reflections of seismic waves from the core-mantle boundary of Mars using InSight seismic data. We constrain the radius of the liquid core to 1830±40 km, consistent with geodetic constraints. The large core precludes a bridgmanite-dominated lower mantle as in Earth with implications for the dynamical evolution of mantle and core. The inferred mean core density ranges from 5.7 g/cm3 to 6.2 g/cm3, implying a considerable fraction of light elements, including S, C, O, and H in the Fe-Ni core. To comply with cosmochemical constraints that limit sulfur to <20 wt.%, the mean core density needs to exceed 6 g/cm3, encompassing the upper end of our estimate. Our results are compatible with a present-day magnetically quiescent dynamo.本研究利用洞察号（InSight）地震数据，探测到了火星核幔边界的地震波反射信号。我们将火星液态核的半径约束为1830±40千米，该结果与大地测量约束结果一致。该巨型火星核排除了与地球类似的、以布里奇曼石（bridgmanite）为主导的下地幔结构，这对幔核系统的动力学演化具有重要启示意义。推算得到的火星核平均密度介于5.7 g/cm³至6.2 g/cm³之间，表明其铁镍核中含有大量轻元素，包括硫（S）、碳（C）、氧（O）与氢（H）。为满足宇宙化学约束中硫含量低于20%重量百分比的要求，火星核平均密度需超过6 g/cm³，这恰好覆盖了我们估算结果的上限区间。本研究结果与现今火星处于磁静息状态的发电机理论相符。