Gurnett D A, Zarka P, Manning R, Kurth W S, Hospodarsky G B, Averkamp T F, Kaiser M L, Farrell W M
Department of Physics and Astronomy, The University of Iowa, Iowa City 52242, USA.
Nature. 2001 Jan 18;409(6818):313-5. doi: 10.1038/35053009.
The detection of impulsive low-frequency (10 to 80 kHz) radio signals, and separate very-low-frequency (approximately 100 Hz) radio 'whistler' signals provided the first evidence for lightning in the atmosphere of Venus. Later, a small number of impulsive high-frequency (100 kHz to 5.6 MHz) radio signals, possibly due to lightning, were also detected. The existence of lightning at Venus has, however, remained controversial. Here we report the results of a search for high-frequency (0.125 to 16 MHz) radio signals during two close fly-bys of Venus by the Cassini spacecraft. Such signals are characteristic of terrestrial lightning, and are commonly heard on AM (amplitude-modulated) radios during thunderstorms. Although the instrument easily detected signals from terrestrial lightning during a later fly-by of Earth (at a global flash rate estimated to be 70 s(-1), which is consistent with the rate expected for terrestrial lightning), no similar signals were detected from Venus. If lightning exists in the venusian atmosphere, it is either extremely rare, or very different from terrestrial lightning.
对脉冲低频（10至80千赫）无线电信号以及单独的甚低频（约100赫兹）无线电“哨声”信号的探测，为金星大气层中存在闪电提供了首个证据。后来，还探测到少量可能由闪电产生的脉冲高频（100千赫至5.6兆赫）无线电信号。然而，金星上闪电的存在一直存在争议。在此我们报告卡西尼号航天器在两次近距离飞越金星期间对高频（0.125至16兆赫）无线电信号的搜索结果。此类信号是地球闪电的特征信号，在雷暴期间的调幅（AM）收音机上通常能听到。尽管该仪器在后来飞越地球时轻松探测到了来自地球闪电的信号（全球闪电发生率估计为70次/秒，这与地球闪电预期发生率相符），但未从金星探测到类似信号。如果金星大气层中存在闪电，要么极其罕见，要么与地球闪电截然不同。
