Towards independent robotic exploration of ocean worlds

NASA is advancing autonomous exploration to tackle one of its foremost goals - investigating the potential for life and habitability on ocean worlds. These missions focus on targets like Jupiter's Europa and Saturn's Enceladus, where subsurface liquid water could support life. Communication delays, extreme environments, and limited energy resources necessitate autonomous robotic systems for such exploration.

To meet these challenges, NASA initiated projects like the Ocean Worlds Lander Autonomy Testbed (OWLAT) at the Jet Propulsion Laboratory (JPL) and OceanWATERS at Ames Research Center. Both serve as platforms for developing robotic autonomy technologies.

OWLAT

OWLAT mimics a lander equipped with a robotic arm for surface operations. Its physical version includes a six degrees-of-freedom (DOF) Stewart platform simulating low-gravity motions, alongside a seven-DOF robotic arm. The arm can perform sampling tasks using tools attached via a quick-connect mechanism, while force/torque sensors monitor interactions with the simulated environment.

The virtual OWLAT, driven by JPL's Dynamics And Real-Time Simulation (DARTS) physics engine, replicates the physical testbed's responses. Both versions rely on a Robot Operating System (ROS)-based interface to execute commands and provide telemetry. This unified interface simplifies transitioning between physical and simulated platforms, enabling robust autonomy software testing.

Safety mechanisms embedded in OWLAT ensure operations remain within defined limits, reporting any anomalies to the autonomy software. This comprehensive system paves the way for safe, effective mission operations on distant ocean worlds.

OceanWATERS

OceanWATERS simulates a robotic lander operating on Europa's surface. This software provides visual and physical simulations, including terrain options resembling environments like Chile's Atacama Desert. It models sunlight conditions, surface properties, and robotic operations such as digging and sampling.

The simulated lander features a 6-DOF arm equipped with a grinder and scoop, powered by a non-rechargeable battery. Autonomy modules, built using open-source tools like PLEXIL, can command the lander and inject simulated faults, such as joint malfunctions or overheating batteries, to test system resilience.

Based on the 2016 Europa Lander Study, OceanWATERS replicates essential mission elements like regolith sampling and battery management. Its unified interface aligns with OWLAT, supporting integrated development of autonomy solutions.

Collaborative Research

The ARROW and COLDTech programs funded six research teams to refine autonomy technologies. Using OWLAT and OceanWATERS, these teams addressed key challenges in surface exploration. Their findings, published in technical papers, contribute software tools that may directly inform future missions to ocean worlds.