VERNE WALKIEE: Wireless Acoustic LinK through Ice on Earth and Europa

Abstract:

Europa is often cited as a promising location for life in our planetary neighborhood due to its young facade and the subsurface ocean implied to be beneath a many kilometers-thick ice shell. Funded by NASA’s SESAME program, the VERNE team (Vertical Entry Robot for Navigating Europa) and several others are actively developing end-to-end mission concepts and technology elements for future through-ice and under-ice missions. Progress indicates an ocean-access mission is feasible in the coming decades (see submission by Bryson et al). To realize ocean access, prior work and the SESAME program estimate a three year mission lifetime during which VERNE would drill through at least a ~15 km thick ice shell. While primary communication from a deployed vehicle to the surface of Europa would occur via tether, unknowns regarding Europa’s geologic activity make it necessary and prudent to consider wireless auxiliary systems to avoid mission failure if the tether breaks. Therefore, the VERNE team deemed a secondary, wireless communications link a necessary supporting technology to ensure mission success. Existing radio frequency technology has enabled reliable, through-ice communication in terrestrial analog environments and can meet spacecraft data transmission requirements; however, high attenuation through ice-water mixtures and water layers--to be expected on Europa--remains a challenge. By contrast, acoustic technologies could be sufficiently robust to close data links through mixed and liquid regimes. The VERNE project’s modeling efforts support complementary acoustic-based communication for data transfer, and suggest piezoelectric transducers already in use for wireless acoustic communication on Earth can be adapted to accommodate communication through ice with expanded benchtop testing and field qualification. Furthermore, a secondary communications system can be utilized in the gathering and transmission of distributed acoustic sensing data, providing structural, compositional, crystallographic, and temperature profiles of the Europan ice shell. Here we present the WALKIEE concept for the secondary communications system aboard a deep-drilling Europan mission, leveraging the work of the VERNE team and collaborators.