Modelling meteor ablation in the venusian atmosphere

Abstract

A comparative study of meteor ablation in the atmospheres of the Earth and Venus is presented. The classical single body meteor ablation model is extended to incorporate a heat penetration depth estimate allowing the simulation of larger meteoroids, than would an isothermal model. The ablation of icy and rocky meteoroids, with densities of 1.0 and 3.4 g cm −3, respectively, and initial radii of up to ∼ 8 mm for rock and ∼ 13 mm for ice (equivalent to an initial mass of 10 −2 kg in both cases), was simulated in both atmospheres. In general venusian meteors are brighter than terrestrial equivalents. Large, slow, rocky objects may be up to 0.7 mag brighter on Venus, while small, icy particles with entry speeds in the range 30–60 km s −1, are found to be upwards of 2.7 mag brighter than at the Earth. Venusian meteors reach maximum brightness at greater altitudes than would similar particles at the Earth. Rocky meteoroids have their points of maximum brightness some 15–35 km higher up at Venus, between 90 and 120 km, whereas, for icy particles this altitude difference is about 5–25 km higher up than at the Earth, in the range 100–125 km. These findings agree, for the most part, with recent analytical studies. Venusian meteors, which last from 100 ms to ∼ 1.5 s , tend to be shorter-lived than terrestrial meteors, with correspondingly shorter visible trails. Large ( ∼ 10 −2 kg ), slow ( ∼ 10 km s −1 ) icy particles reach a maximum magnitude of ∼−2 at Venus and remain visible for about one second, with a large section of the smaller faster meteoroids simulated here remaining visible for several hundred milliseconds. In light of recent space-based meteor observations at the Earth [Jenniskens, P., Tedesco, E., Muthry, J., Laux, C.O., Price, S., 2002. Meteorit. Planet. Sci. 37, 1071–1078], such brightness, height and duration estimates as suggested in this work, may be used in developing future observational campaigns to be carried out from Venus orbit.