GPRE 7 5KNTA Test 1E81b

a calm clear high-desert October evening, Interorbital Systems’ NEPTUNE rocket series’ main engine roared to life in its first hot-firing test. The engine, the IOS GPRE (General Purpose Rocket Engine; 7,500lb-thrust; Nitric Acid; Turpentine; Ablative cooling), blasted a 22-foot () plume of fire across Interorbital’s Mojave Spaceport test area, scorching the sand an additional 50 feet ( meters) beyond the plume end. The all-composite-chambered (33,362-newton) thrust engine is the largest rocket engine in the world utilizing high-density, storable nitric acid and turpentine. These hypergolic propellants provide almost instantaneous chemical ignition. This static firing marks a major milestone in the evolution of the company’s NEPTUNE Modular Orbital Launch Vehicle series. Refining the engine operation paves the way for the first flight test of the CPM---Common Propulsion Module—the stand-alone rocket that is the primary construction element of various bundled configurations that yield launch vehicles specially designed to meet specific mission requirements. IOS’ first orbital launcher is a seven-module rocket designated the NEPTUNE 7 (N7)---a three-stage orbital vehicle powered by seven GPRE engines---and purposed to lift a mixed-manifest of some 24 TubeSats and CubeSats on each launch. Interorbital recently completed a NASA Phase I SBIR contract, awarded to further the development of the NEPTUNE Modular Rocket series.