Perseverance MEDA Atmospheric Pressure Observations - Initial Results

The Mars2020 Perseverance Rover landed successfully on the Martian surface on the Jezero Crater floor (18.44°N, 77.45°E) at Martian solar longitude of 5 degrees in February 2021. Since then it has produced highly valuable environmental measurements with a versatile scientific payload including the MEDA (Mars Environmental Dynamics Analyzer) suite of environmental sensors. One of the MEDA systems is the PS pressure sensor system which weighs 40 grams and has an estimated absolute accuracy of better than 3.5 Pa and a resolution of 0.13 Pa. We present initial results from the first 414 sols of Martian atmospheric surface pressure observations by the PS whose performance was found to meet its specifications. Observed sol-averaged atmospheric pressures follow an anticipated pattern of pressure variation in the course of the advancing season and are consistent with data from other landing missions. The observed daily pressure amplitude varies approximately by 2-5 % of the sol-averaged pressure, with absolute amplitude 10-35 Pa in an approximately direct relationship with airborne dust. During a regional dust storm, which began at the 135 degrees of solar longitude the daily pressure amplitude roughly doubles. The daily pressure variations were found to be remarkably sensitive to the seasonal evolution of the atmosphere. In particular analysis of the daily pressure signature revealed diagnostic information likely related to the regional scale structure of the atmosphere. Comparison of Perseverance pressure observations to data from other landers reveals the global scale seasonal behaviour of Mars' atmosphere.

2021年2月，火星2020毅力号火星车（Mars2020 Perseverance Rover）成功着陆于火星杰泽罗撞击坑坑底（北纬18.44°，东经77.45°），着陆时火星太阳经度为5度。自着陆以来，该火星车搭载多用途科学载荷，其中涵盖火星环境动力学分析仪（MEDA, Mars Environmental Dynamics Analyzer）传感器套件，获取了极具科学价值的环境探测数据。MEDA套件中的一款子系统为PS压强传感器系统，其质量仅为40克，预估绝对精度优于3.5帕（Pa），分辨率达0.13帕。本文呈现了该PS系统前414个火星日（sol）的火星地表大气压强观测初始结果，经检验其性能完全符合设计指标。观测得到的火星日平均大气压强随季节推进呈现出预期的变化规律，与其他着陆任务获取的观测数据保持一致。观测到的每日压强振幅约为火星日平均压强的2%至5%，绝对振幅介于10至35帕之间，且与大气悬浮尘埃含量大致呈直接正相关关系。在一场始于太阳经度135度的区域性沙尘暴期间，每日压强振幅约提升一倍。研究发现，每日压强变化对火星大气的季节演化极为敏感；通过对每日压强特征的专项分析，可获取与火星大气区域尺度结构相关的诊断性信息。将毅力号的压强观测数据与其他着陆器的观测数据进行对比，可揭示火星大气的全球尺度季节变化特征。