Science Seminars

11/03/2016 – Xu Wang; Electrostatic Dust Transport to Reshape The Surfaces of Airless Planetary Bodies

Speaker: Xu Wang (CU)
Date: Tuesday, Nov 03, 2020
Time: 4:00 PM
Location: SPSC W120

Seminar Abstract:

Airless bodies unlike our Earth are directly exposed to solar UV radiation and solar wind plasma. Their surfaces covered by fine-sized regolith dust will be charged and may be mobilized due to electrostatic forces. This electrostatic process has been first suggested five decades ago to explain the so-called ‘lunar horizon glow’, a bright cloud observed over the horizon shortly after the lunar sunset. Since then, a number of observations have been linked to this electrostatic transport hypothesis, such as the intermittently appearing radial spokes in the Saturn’s rings, the ponded dust on the surfaces of asteroid 433 Eros and comet 67P, unexpectedly smooth surface on Saturn’s icy satellite Atlas and high surface porosity indicated from asteroid spectra.
These mysterious space observations have attracted much interest to figure out the mechanisms behind them, including both simulation works and lab experiments that have indeed demonstrated this electrostatic process. However, there were no satisfied charging theories to explain it. We recently made a breakthrough with our new lab experiments, and developed a new ‘patched charge model’ in which micro-cavities in the surface and photo-/secondary electrons play a critical role. Detailed results will be presented, including the videos of dust hopping recorded with a high-speed camera.
Our work suggests that this electrostatic process should work for all airless planetary surfaces to redistribute fine dust particles, which will consequently change the surface features (e.g., surface morphology, porosity) and the surface processes (e.g., space weathering). I will briefly touch a just initialized CubeSat mission idea to land instruments on a near-Earth-asteroid (NEA) to explore this possible phenomenon.