This stage introduces the foundation of the entire SLPA philosophy by examining the elegant physics of the steam locomotive: a system that converts stored heat into motion using a simple cycle of heating, vaporisation, expansion, and mechanical work.
Their success came from a straightforward physical loop:
The key insight is that motion does not require chemical fuel in the exhaust—only stored heat and a working fluid.
The locomotive demonstrates a universal truth: any system that stores heat and expands a working fluid can produce motion.
SLPA adopts this principle exactly, but replaces the boiler and piston with advanced thermal storage and high‑temperature gas thrusters.
Modern spacecraft typically rely on chemical or electric propulsion, both of which have limitations. The locomotive model shows a third path: heat‑driven propulsion using a working gas. This insight becomes the conceptual bridge into Stage 2, where SLPA is introduced as a complete architecture built around this principle.
Steam locomotives prove that stored heat + a working fluid = motion. SLPA uses the same logic for spacecraft, replacing metal boilers with thermal mass cores and pistons with advanced gas‑expansion thrusters.