Phase Four's Second Generation RF Thruster, Maxwell Block 2, firing in one of the company's vacuum chambers. Credit: Phase Four

PARIS — Phase Four’s Maxwell Block 2 radio-frequency thruster has been demonstrated on a commercial satellite.

“It’s in space and its actually working great,” Umair Siddiqui, Phase Four chief technology officer, told SpaceNews at the World Satellite Business Week conference here. “No issues with that system.”

Phase Four is not yet revealing the name of the satellite customer.

Mr. Potato Head

Maxwell Block 2 draws on the heritage of Phase Four’s Block 1 thruster first demonstrated in orbit in 2021. The primary difference between Block 1 and Block 2 is the new thruster’s modularity.

“Block 1 was packed into a tiny form factor,” Siddiqui said. “Block 2 has taken the components and basically turned them into a Mr. Potato Head of systems. In other words, we can separate the components.”

In addition, Maxwell Block 2 is designed for mass manufacturing and “is higher performing than Block 1 without increasing input power,” Siddiqui said. “It’s designed to directly compete with Hall-effect thrusters.”

Maxwell Block 3

In a vacuum chamber in Hawthorne, California, Phase Four is testing Maxwell Block 3.

Each new Block is “an iteration on the core product we’ve been developing since 2018,” Siddiqui said. “As we go through iterations, we get performance improvements and operational improvements.”

Maxwell Block 3 “has achieved the performance with krypton that’s equivalent thrust ISP [specific impulse] to a Hall-effect thruster,” Siddiqui said. “It’s the first time any cathodeless thruster has been able to achieve that.”

Phase Four plans to begin delivering Block 3 to customers in June 2024.

Xenon or Krypton

All Maxwell thrusters are designed to operate on either xenon or krypton propellant. In spite of higher xenon prices, Phase Four’s early customers chose xenon for their small satellites.

Phase Four’s latest customers are opting for larger satellites with larger propellant tanks.

“Now, they’re trending toward krypton, which is good for us because our thruster works better on krypton than it does on xenon,” Siddiqui said.

“Now, they’re trending toward krypton, which is good for us because our thruster works better on krypton than it does on xenon,” Siddiqui said.

Debra Werner is a correspondent for SpaceNews based in San Francisco. Debra earned a bachelor’s degree in communications from the University of California, Berkeley, and a master’s degree in Journalism from Northwestern University. She...