The Saturn‐orbiting Cassini spacecraft completed 126 close Titan flybys from 2004 until 2017. During almost all of them the Cassini Radio and Plasma Wave Science (RPWS) instrument was turned on to search for radio emissions attributed to Titan lightning. Here we report about their nondetection after close inspection of all Titan flybys throughout the Cassini mission. We also infer new and strong constraints on the permissible flash energy and flash rate of potential Titan lightning. The nondetection of lightning flashes by Cassini observations implies that any lightning on Titan must be either very weak, very rare, or does not exist at all, and the latter could be due to cloud electric fields being too low to initiate a discharge. This finding holds important implications for the prebiotic chemistry of Titan and also implies that lightning will not be a significant hazard to the upcoming Dragonfly mission.

中文翻译：

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卡西尼号RPWS未检测到泰坦闪电发出的无线电辐射

从2004年到2017年，土星轨道的卡西尼号飞船完成了126次泰坦近距离飞越。在几乎所有飞行过程中，卡西尼号和等离子波科学（RPWS）仪器都被打开以搜索归因于泰坦闪电的无线电辐射。在这里，我们报告了在整个卡西尼号飞行任务中仔细检查所有泰坦飞掠物之后未发现它们的情况。我们还推断出潜在的土卫六闪电的允许闪光能量和闪光速率受到新的强烈限制。卡西尼号观测器未检测到闪电闪烁，这意味着土卫六上的任何闪电都必须非常弱，非常稀有或根本不存在，而后者可能是由于云电场太低而无法引发放电。