What is phase four?
Phase Four is a propulsion company whose multi-mode thruster technology Quantum Space acquired in September 2025 — it's now the engine powering the Ranger spacecraft.
Why it matters: The acquisition gives Quantum Space a single propulsion system that handles both high-thrust chemical maneuvers and efficient electric propulsion, critical for the long-range cislunar missions the company is pitching to the Pentagon.
- Phase Four built the Maxwell radio-frequency (RF) thruster, which combines chemical and electric thrust in one unit — letting Ranger operate efficiently across low-Earth orbit, GEO, and cislunar space.
- Quantum Space took over Phase Four's Hawthorne, CA integration and test facility, which can produce up to 100 engines per year.
- The deal transferred Phase Four's full IP portfolio and manufacturing equipment; financial terms were not disclosed.
