Expellis

Expellis is a term used in speculative technology and science fiction to describe a class of devices designed to perform controlled expulsion of matter, energy, or payloads from a system. In many portrayals, expellis systems are compact, energy-efficient, and capable of directing a high-velocity discharge with minimal disturbance to the surrounding environment.

Etymology and usage notes indicate that expellis draws from the Latin expellere, meaning to drive out, combined with a modern technical suffix to form a noun for a device or process. The concept often appears in glossaries of advanced propulsion or waste-management technologies within fictional settings, where it is treated as a distinct mechanism from conventional propulsion or combustion.

Design characteristics commonly attributed to expellis include a containment chamber, a rapid actuation or release valve, and a directing element such as magnetic, aerodynamic, or fluidic channels that shape the expelled output. Depending on the depiction, the expelled medium can be gas, plasma, solid particulates, or a combination, and the system may emphasize rapid discharge, low recoil, or self-contained energy management.

Applications in fiction typically span spacecraft debris clearance, industrial material handling, or defense-oriented payload ejection. In theoretical discussions, expellis is used as a thought experiment to contrast expulsion-based methods with pressure-driven or reaction-based propulsion, highlighting trade-offs in efficiency, control, and thermal management.

Overall, expellis remains a speculative construct without real-world implementation, serving as a narrative and conceptual tool for exploring how deliberate expulsion could be integrated into engineered systems.