Electrospray charging of minerals and ices for hypervelocity impact research

Microparticle impacts are an important solar system process, and laboratory experiments are essential to understanding both microcratering and the results from in situ cosmic dust analyzers. However, current dust accelerators can only use conductive projectiles, limiting projectile types and possibly complicating studies of microparticle impact chemistry. We present a charging method that eliminates the need for conductive projectiles by using electrospray, instead of contact charging, to electrically charge microparticles. Using this novel application of electrospray, charged microparticles of quartz, quartz–ice aggregate, and methanol–water ice have been produced and observed. These experiments also demonstrate that the quartz surface can be protonated under non-equilibrium electrospray conditions, implying that the quartz surface may have a point of zero charge. Although coupling an electrospray source to a dust accelerator presents challenges, electrospray charging of minerals, mineral–ice aggregates, and astrophysical ices may enable experiments with projectiles that more closely resemble actual solar system materials.