中文摘要：

历史上几乎所有的行星探测任务都开展了无线电掩星实验，以探测行星的大气、电离层、行星环以及磁场，并取得了很多重要的科学成果．掩星发生时刻前后，测量航天器发出的信号穿过行星电离层和大气层时被遮掩而引起的信号频率、相位、幅度或极化等物理特性的变化，通过某种反演技术，可以得到大气的折射率廓线，推出中性大气的密度、温度、压强廓线以及电离层的电子浓度廓线．文章围绕中国“萤火1号”火星探测器（YH-1）火星探测计划中将要开展的星一地无线电掩星实验，介绍了该技术用于探测火星大气和电离层的相关情况．

英文摘要：

Investigations of planetary atmospheres, ionospheres, rings, and magnetic fields using radio science techniques have been conducted by almost every planetary mission, and have acquired many significant scientific results. Changes in the frequency, phase, amplitude and polarization of spacecraft radio signals, caused by passage through a planet＇s atmosphere and ionosphere, have been observed in rising and descending planet occultation events. Utilizing an inversion method, we can obtain the refractivity profiles of the atmosphere, as well as the density, temperature and pressure profiles of the neutral atmosphere, and the electron density profile of the ionosphere. In the first Chinese YH-1 Mars mission, characteristics of the Martian atmosphere and ionosphere will be detected by a radio occultation experiment. The details are presented in this paper.