The tropospheric propagation effect is one of several sources of error in radio science measurements. Systematically calibrated for the Earth troposphere disturbances, the ranging and Doppler data provided by the Martian landers have not been corrected so far for Mars troposphere effects. These effects were considered negligible because the Mars atmosphere is a hundred times less dense than that of the Earth. The constantly improving lander data accuracy and the challenging science objectives of the InSight‐Rotation and Interior Structure Experiment (RISE) and ExoMars‐2022‐LaRa radio science experiments motivated this work. We propose here a simple model to compute the Mars troposphere errors affecting a radio wave transponded from the surface of Mars. The troposphere zenithal delay is first derived from the surface pressure at the lander location. We use a mapping function to infer the slant delay (range errors) induced by the troposphere of Mars. Being proportional to range rates, the contribution of Mars troposphere to the Doppler measurements is derived from the slant delays. Using our model, an elevation threshold of 15° above the lander is identified, below which the Doppler data should be calibrated for Mars troposphere. When applied to the X‐band Doppler data from Mars surface missions, the model predicts significant Mars troposphere contribution for less than 1% of RISE data, 2% of Opportunity data, and 2.5% of Pathfinder data. Among these tracking passes, some are strongly affected by the troposphere of Mars, with Doppler errors reaching sometimes more than 3 times the nominal noise level (>10 mHz at 60 s integration time).

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火星对流层火星登陆器无线电科学数据校准

对流层传播效应是无线电科学测量中几种误差源之一。对于地球对流层扰动进行了系统校准，到目前为止，火星登陆器提供的测距和多普勒数据尚未针对火星对流层效应进行校正。人们认为这些影响可以忽略不计，因为火星大气层的密度比地球低一百倍。InSight旋转和内部结构实验（RISE）和ExoMars-2022-LaRa无线电科学实验的不断提高着陆器数据准确性和具有挑战性的科学目标推动了这项工作。我们在这里提出一个简单的模型来计算影响对火星表面发射的无线电波的火星对流层误差。对流层天顶延迟首先从着陆器位置的表面压力得出。我们使用映射函数来推断由火星对流层引起的倾斜延迟（距离误差）。与测距速率成正比，火星对流层对多普勒测量的贡献来自倾斜延迟。使用我们的模型，确定了着陆器上方15°的仰角阈值，在该阈值以下，应针对火星对流层校准多普勒数据。当将其应用于来自火星地面任务的X波段多普勒数据时，该模型将预测不到1％的RISE数据，2％的机会数据和2.5％的探路者数据对火星对流层的贡献很大。在这些跟踪通道中，有些受到火星对流层的强烈影响，多普勒误差有时达到标称噪声水平的三倍以上（在60 s积分时间内> 10 mHz）。