Phase Four unveils iodine propellant engine

Phase Four Inc., the creator of the radio-frequency thruster for satellite propulsion, will expand its Maxwell turn-key plasma propulsion line and offer satellite manufacturers a high-performance engine using an inexpensive, domestically sourced iodine-based propellant. Max-V leverages the Maxwell Block 2 engine's modular architecture and builds on the radio-frequency thruster's propellant-agnostic capabilities.

"Legacy electric propulsion systems are tied to noble gases like xenon and krypton," said Phase Four CEO Beau Jarvis. "These noble gases, while high performing, are largely sourced outside of the United States in China, Russia, and Ukraine. The U.S. has no real control over this supply chain, which is subject to high price volatility and recent severe supply issues." Phase Four board member, former NASA Administrator Jim Bridenstine observed, "This year we've seen xenon prices spike to over $30,000 per kilogram. This is cost prohibitive for both commercial and government satellite constellations in low Earth orbit." Bridenstine continued, "The U.S. is the world's third largest iodine producer, and my home state of Oklahoma leads the way in domestic production. With Max-V, we can ensure a fully domestic supply chain and readily accessible low-cost propellant."

Phase Four's Maxwell Block 1 engine flew in early 2021. Maxwell Block 2 engine deliveries began earlier this year. With double-digit commercial flight units delivered, the company is now focusing on its Max-V development effort. Maxwell's new chassis-style design enables rapid on-ramping of improvements in the core areas of the thruster, power electronics, and propellant subsystems. This architecture is streamlining the Max-V development process as is the company's significant experience with iodine-based propellants through its recent U.S. Air Force AFWERX award.

"Maxwell's new modular chassis architecture enables us to introduce improved capabilities within the same form factor," said Phase Four CTO, Umair Siddiqui. "Using an iodine-based propellant instead of a noble gas propellant stored at very high pressure provides a number of benefits to our customers. Iodine stores as a solid without high pressure valves or vessels, which means we can deliver fully fueled engines directly to our customers." Siddiqui continued, "Iodine also stores about 3x more densely than xenon, which means our propulsion systems will offer much higher total impulse in the same unit volume as legacy electric propulsion systems."

"We've always said that Phase Four delivers game changing propulsion systems, and Max-V will do just that," Jarvis said. "We are building a product that will dramatically lower costs and extend operational lifetimes of small satellites in low Earth orbit and provide significantly higher total impulse for missions beyond LEO."

Max-V is anticipated to be available for order in the second half of 2023. The system is designed to operate from 200W to 1.5kW, and achieve 50mN thrust, over 1,200 s Isp and deliver more than 100kN total impulse. Max-V's iodine-based propellant will cost under $400 per kilogram and be incorporated in the purchase price. Max-V's form factor is similar to Phase Four's current Maxwell Block 2 engine. The system will ship fully fueled, ready for installation and will require no ground fueling operations prior to launch.