The Griffiths ISRU‑Powered Plasma Hopper (IMPH) is a disc‑shaped planetary surface lander and hopper designed to achieve long‑range mobility on bodies where in‑situ resources are readily available. Instead of carrying propellant from Earth, the IMPH extracts local feedstock such as CO₂ from the Martian atmosphere, H₂O ice from lunar or Martian deposits, or CH₄ from Titan’s lakes. These feedstocks are cracked using an integrated GNMT microwave power module to produce plasma‑ready gas, which is then accelerated through a shear‑stabilized electromagnetic nozzle to generate thrust. The result is a vehicle capable of repeated hops ranging from 10 to 500 km, with effectively unlimited total range because each hop is followed by ISRU refuelling.

The architecture addresses the fundamental limitations of traditional plasma thrusters—Kelvin‑Helmholtz instabilities, anomalous cross‑field transport, and plasma‑wall erosion—by engineering controlled velocity shear in the exhaust. Differential propellant injection creates velocity gradients of 50–500 km/s per metre over centimetre‑scale radial distances. These gradients produce viscous dissipation that exceeds instability growth rates, maintaining stable plasma behaviour without complex magnetic topologies or active feedback. Stability is quantified using the Richardson number, with IMPH operating in the Ri = 0.5–2.5 regime across all modes, well above the classical instability threshold.

The vehicle operates in three modes. Mode A (10–50 kW, 5–15 N, Isp 1,500–2,500 s) handles plasma conditioning, precision landing, and low‑power manoeuvres. Mode B (50–200 kW, 20–60 N, Isp 2,500–3,500 s) performs primary ascent and descent burns for standard hops. Mode C (200–500 kW, 60–150 N, Isp 3,500–5,000 s) supports long‑range hops and higher‑gravity operations, using superconducting coils to maintain confinement at high plasma density. All mode transitions are software‑controlled, requiring no mechanical reconfiguration.

The GNMT microwave module provides 70–85 percent coupling efficiency and operates at 13.56 or 27.12 MHz using GaN solid‑state amplifiers. Solar arrays sized for 10–500 kW input power supply the system, with battery buffering enabling burst‑mode operation. ISRU feedstock processing varies by target body: CO₂ adsorption for Mars, microwave sublimation for H₂O ice, and direct collection for Titan’s methane lakes. Feedstock purity requirements are relaxed because molecular dissociation products are intrinsic to plasma cracking.

The electromagnetic confinement system uses 300–2,000 Gauss fields with mirror ratios of 10–30, achieving 75–85 percent thermal‑to‑kinetic conversion efficiency. Plasma detachment occurs reliably once exhaust velocity exceeds the local Alfvén velocity. The shear‑stabilized nozzle maintains KH stability margins of 2–8× depending on mode.

Mission applications include Mars polar traverses, crater‑floor access, multi‑site geological surveys, lunar polar ice exploration, Titan hydrocarbon surveys, Enceladus and Europa vent‑region access, and microgravity hopping on C‑type asteroids. Compared to rovers, chemical hoppers, or helicopters, the IMPH uniquely combines long‑range mobility, terrain independence, and full ISRU capability. The primary operational constraint is ISRU refuelling time, which ranges from hours to days depending on local resource quality and solar power availability.