Characterization of a 2700 ​km long bolide airburst chain, Phoebe Regio, Venus

Abstract

Detailed geological mapping of Phoebe Regio on Venus, located near 10°S, 282°W, at a scale of 1:500,000, provided the basis for the discovery of a linear trend with 12 splotches, herein termed the Phoebe Regio Splotch Chain. The formation of splotches on the surface is associated with an explosion that occurs as a result of the interaction of a cosmic body penetrating through the dense atmosphere of Venus. The shockwave from such an air-blast could affect the surface in different ways, leading to both radar darkening and brightening. It was found that the 12 splotches differ in size but have a similar morphology and include a dark center and a radar-bright ring. The presence of such characteristics makes it possible to distinguish splotches from other geological features such as volcano-tectonic features (volcanic edifices, pyroclastic mantles, portions of lava flows and associated structures), which, when analyzed on a broad scale, can look similar. Splotches are known to be among the youngest geological features on the surface of Venus, and the elongated distribution of 12 splotches is suggested to have been formed by a stream of individual fragments of a parent body that disrupted well before entering the atmosphere of Venus.