Science. 1980 Jan 25;207(4429):446-9. doi: 10.1126/science.207.4429.446.
Radio occultation measurements at S band (2.293 gigahertz) of the ionosphere and upper neutral atmosphere of Saturn were obtained during the flyby of the Pioneer 11 Saturn spacecraft on 5 September 1979. Preliminary analysis of the occultation exit data taken at a latitude of 9.5 degrees S and a solar zenith angle of 90.6 degrees revealed the presence of a rather thin ionosphere, having a main peak electron density of about 9.4 x 10/(3) per cubic centimeter at an altitude of about 2800 above the level of a neutral number density of 10(19) per cubic centimeter and a lower peak of about 7 x 10(3) per cubic centimeter at 2200 kilometers. Data in the neutral atmosphere were obtained to a pressure level of about 120 millibars. The temperature structure derived from these data is consistent with the results of the Pioneer 11 Saturn infrared radiometer experiment (for a helium fraction of 15 percent) and with models derived from Earth-based observations for a helium fraction by number of about 4 to 10 percent. The helium fraction will be further defined by mutual iteration with the infrared radiometer team.
1979 年 9 月 5 日，先驱者 11 号土星飞船飞越土星时，在 S 波段（2.293 千兆赫）对电离层和上层中性大气进行了射电掩星测量。对在南纬 9.5 度和太阳天顶角 90.6 度处获得的掩星出口数据的初步分析表明，存在一个相当薄的电离层，在中性数密度为 10^19 每立方厘米的水平上方约 2800 处具有主要峰值电子密度约为 9.4 x 10^3 每立方厘米，在 2200 公里处具有较低峰值约为 7 x 10^3 每立方厘米。中性大气中的数据获取到约 120 毫巴的压力水平。从这些数据得出的温度结构与先驱者 11 号土星红外辐射计实验的结果（氦分数为 15%）一致，也与基于地球观测的氦分数为 4 到 10%的模型一致。氦分数将通过与红外辐射计团队的相互迭代进一步确定。
