火星无线电掩星探测进展

Progress of radio occultation exploration of Mars

火星是地球的姊妹星,研究火星对了解火星、地球乃至太阳系的演化具有重要意义.自从1964年美国水手4号发射,首次成功地运用无线电掩星技术探知到火星的环境特征之后,国际上不少的火星任务都开展了掩星实验,取得了重要进展.本文依据采用了无线电掩星技术进行勘探的火星探测器发射时间顺序展开调研,针对具有开创性的水手系列、火星全球勘测者、火星快车、火星大气挥发演化探测器、天问一号等,梳理分析和总结了各任务的火星无线电掩星方式以及所获取的廓线数量、位置分布、获取方式等产品信息,以及部分相关的研究结果.本文还分析了当前火星无线电掩星探测方式存在的局限性,并探讨了可能的对策.火星无线电掩星后续可重点考虑多颗星-星掩星结合星-地掩星方式形成掩星星座;并通过选用适当的信号探测频率、改进反演算法等方式进一步提高掩星质量;火星掩星探测手段还可与火星顶部探测雷达、直接探测等手段相结合,发展火星多源数据融合技术.随着探测方式的不断改进,无线电掩星探测将是火星探测的重要手段.未来会有数量越来越多、时间与空间覆盖越来越全面、精度越来越高的掩星数据用于火星的整个空间环境研究,包括大、中尺度乃至小尺度结构的特征与演化规律都将被人类掌握.

Mars is the sister star of Earth.Studying Mars is important to understand its evolution as well as that of Earth and even the solar system.Since the launch of American Mariner 4 in 1964 and the first successful use of radio occultation technology to explore the environmental characteristics of Mars,many international missions to Mars have conducted occultation experiments and made important progress.This article investigates Mars probes based on their launch time sequence,which utilized radio occultation techniques for exploration,focusing on groundbreaking missions such as the Mariner series,Mars Global Surveyor,Mars Express,Mars Atmosphere and Volatile Evolution,and Tianwen-1.We review,analyze,and summarize the product information,including the number and distribution of profile measurements,and the methods of acquisition obtained from each mission's radio occultation.Additionally,this article analyzes the limitations of the current Mars radio occultation approaches and explores possible countermeasures.Mars radio occultation can be further improved by considering the mode of star-star occultation combined with star-ground occultation to form occultation constellation,choosing an appropriate signal detection frequency,and improving the inversion algorithm.It can also be combined with the Mars top detection radar and direct detection means to develop multi-source data fusion.With the continuous improvement of detection modes,radio occultation detection will be an important tool for Mars exploration in the future.Detections will grow in number and become increasingly more comprehensive in time and space coverage,and more ac-curate occultation data for the entire space environment of Mars will be obtained,including large,mesoscale,and even small-scale structure characteristics and evolution laws.