Sampling the volcanic plumes at Io: Impact speeds and shock conditions

Abstract The desire to sample material from the interior of Io, by flying through its volcanic plumes, requires consideration of the flyby speed and the types of sample collection techniques that can be utilized. Low speed collection (1–2.5 km s −1 ) would require an orbit around Io itself, which is unlikely due to the accumulated radiation dose that would be experienced. Moderate collection speeds (7–9 km s −1 ) are possible for flybys of Io arising from either a single passage through the Jovian system (followed by sample return) or a carefully selected orbit around Jupiter that has the main purpose of visiting Io. However, even if they include an Io close passage, most Jovian mission orbit concepts also include and even prioritize other science objectives, resulting in orbits with Io collection speeds of around 17–19 km s −1 (or greater). Depending on the speed and collector material, the peak shock pressures during collection may thus range from 5 to hundreds of GPa for impacts on solid, nonporous media, with pressures from 0.01 to 5 GPa for impacts on low‐density aerogels. These shock pressures are calculated herein for a range of Io encounter speeds and collector types, and the degree of sample capture and impact processing are estimated. While capture of material is shown to be possible at speeds up to 10 km s −1 , permitting both in situ analysis or sample return to Earth, above these speeds retention of significant amounts of unvaporized material in a collector is not viable.