South Korea’s solid‑fuel space launch vehicle, commonly abbreviated GYŪB (Korean: Goche Yeonlyo Uju Balsache or 고체연료 우주발사체), is an orbital booster developed by the state-run Agency for Defense Development (ADD). It is based on solid propellant stages, with a liquid-fuel post‑boost stage (PBS), designed to deploy small satellites—particularly synthetic aperture radar (SAR) reconnaissance payloads—into low Earth orbit as part of the country’s independent space-based surveillance capability.