Design of a Novel Lunar Transportation System (FLOAT) consisting of Diamagnetically-Levitated Robots on a Flexible Film Track

A durable, long-life robotic transport system will be critical to the daily operations of a sustainable lunar base in the 2030’s, as envisioned in NASA’s Moon to Mars plan and mission concepts like the Robotic Lunar Surface Operations 2 (RLSO2), to transport regolith mined for ISRU consumables (H2O, LOX, LH2) or construction, and transport payloads around the lunar base and to / from landing zones or other outposts. In this work, we present the component and system design for a novel lunar transportation system FLOAT (Flexible Levitation on a Track) that leverages diamagnetically levitated robots with the capacity to move >100,000 kg of regolith multiple kilometers per day while consuming <10 kW of power. Unlike, current lunar robots that use wheels (SEV, RASSOR), legs (Spidernaut), or wheel- on-leg hybrids for mobility, FLOAT robots are solid-state (no motors, gearboxes, or other moving parts) and consist only of permanent magnets connected in planar arrays levitating over the track to minimize lunar dust abrasion / wear.The FLOAT system (demonstrated in sub-scale prototypes at TRL 3 / 4, and based on the Diamagnetic Micro Manipulation (DM3) technology from SRI International) employs 100s to 1000s of unpowered magnetic robots (∼1x1 meter size, ∼30 kg/m2 payload capacity) that levitate over a 2-layer flexible film track: a graphite layer enables robots to passively float over tracks using diamagnetic levitation, and a flex-PCB circuit layer generates electromagnetic thrust to controllably propel robots along tracks. Here we refine models of robot levitation force under lunar conditions, for multiple robot / track designs (e.g. magnet size / pattern, track layer thicknesses), and identified manufacturable robot / track configurations that achieve 50- 100 μm levitation gaps (1-2x mean lunar regolith particle sizes) while carrying >30 kg/m2 payloads. We also developed analyt- ical models of electrical power required to propel robots with a range of payloads / velocities up slopes of varying steepness and around turns of various radii of curvature; and built finite- element models to estimate required robot compliance to con- form to varying lunar terrains (and confirmed model agreement with tests of physical compliant robot prototypes). Results show that FLOAT robots maintain extremely low power requirements over a range of terrains – using <5 W/m2 or <0.15 W/kg to carry up to 30 kg/m2 payload on tracks with slopes <40◦ and curves >5 m in-plane radius or >25 m out-of-plane radius – and use 10-100x less power for transport than wheeled vehicles.Additionally, we build a model that combines the robot / track performance estimates from our prior results with parameters of the Robotic Lunar Surface Operations 2 (RLSO2) mission concept to generate system design estimates – e.g. number of robots, length of track, peak power consumption, and mass / vol-ume – for a complete transportation system that meets RLOS2 regolith volumetric flow requirements. Finally, we introduce potential CAD concepts for track deployment robots (used to unroll segments of FLOAT tracks onto the lunar regolith) and full-size FLOAT robots.