Non-evidence of lightning and associated volcanism at Venus

Abstract

Reports of unpredicted ‘lightning’ and its spatial association with mountains of possible volcanic origin are provocative features of the 1980's literature on Venus. These reports are based upon interpretation of low-frequency 100 Hz electric field noise observed from the Pioneer Venus Orbiter during 1978–1986. These speculations have been repeatedly challenged in the literature. Even though explosive volcanism, like lightning, is discounted in the literature, researchers have been prompted to believe in present-day eruptions by the suggestion that volcanic plumes might stimulate the otherwise unexpected lightning. Recent introductions of a distinct set of higher-frequency electric field noise has resulted in further claims for lightning, but these results, like those derived from the 100 Hz data are discounted be several independent studies. Commenting on the large body of 100 Hz data, Russell (1991) abandons earlier reports of the planetographic clustering of this noise, and states that active volcanoes are not the source of the Venus ‘lightning’. This welcome acknowledgement leaves unresolved problems. First, this brief comment is quite insufficient to correct the widespread and flawed perception that Venus is currently experiencing widespread lightning, stimulated by volcanic disturbances. Second, this admission leaves unexplained the origin of the voluminous 100 Hz data set. The foregoing problems, combined with negative results of recent independent studies, indicate strongly that the Pioneer Venus results provide no reliable evidence of either lightning or volcanism at Venus.