Description: This Phase II proposal focuses on an innovation to resolve the sediment problem in deep ice drilling. Accumulated insoluble debris could hinder descent of a cryobot (ice-penetrating robot) on a mission to explore icy ocean worlds or ice strata on Mars. Section S13:01 of the 2022 SBIR solicitation stated: “preference will be given to those proposals that would benefit in situ studies of icy ocean worlds, especially techniques that would be beneficial to systems that will descend through kilometers of cryogenic ice.” The MJOLNIR innovation aims to address this call by mitigating the risk of debris accumulation for cryobots by periodically creating “side pockets” in the ice where debris can be sequestered. Phase I work used computational fluid dynamic particle tracking code to model a wide range of parameters that affect the ability to move collected insoluble material into sequestration pockets. We identified a feasible CONOPS: 1) downward closed-cycle hot water drill (CCHWD) jetting proceeds until the vehicle descent is slowed due to debris collection; 2) it switches to passive melting until the nose reaches the debris accumulation; 3) lateral jets near the nose cut deep side pockets; 4) jet flow turbulence moves the particles into the pockets; 5) the vehicle resumes passive melting to slowly move past the side pockets as particles settle out in the pockets; and 6) the vehicle resumes CCHWD jetting descent. Phase II focuses on three laboratory investigations: 1) measuring ground truth geometry of the sequestration pockets created under a wide range of jet parameters; 2) testing the ability to sequester a wide range of insoluble particles; and 3) examining the effect of ice temperature on the side pocket approach. The CCWD approach enables cryobots to breach debris-laden ice and the MJOLNIR innovation will provide debris mitigation enabling long descent distances. NASA mission applications include exploration of Mars polar ices and all ice-covered ocean worlds.

Benefits: MJOLNIR allows ice-penetrating cryobots such as THOR to breach debris-laden ice (ice fraction >50%), providing steady state debris mitigation over long descent distances. Potential NASA mission application include: Mars polar cap (2-3 km) subsurface access and sampling; Europa’s 10-40 km ice crust with ocean access; Ganymede’s rocky ice crust for strata and sampling studies; Enceladus’s estimated 10-40 km thick ice crust with ocean or cryovolcanic access; and other icy ocean worlds

The MJOLNIR system may be implemented on terrestrial hot water drill rigs to manage sediment for glacial and astrobiological investigations: Basal access to bedrock layer through heavily debris-laden ice at base of ice sheets in Antarctica and Greenland; heavy debris alpine glacier penetration for strata-based sampling, and access to subsurface water conduits; volcanic caldera glaciers