Phase Four aims to catalyze infrastructure expansion in space through the deployment of electrodeless RF propulsion systems, regular batch manufacturing, and development of advanced propellants.


Phase Four’s Maxwell RF thruster does not implement cathodes anywhere in the system. This eliminates the choke point slowing down manufacturing of traditional plasma propulsion systems.

At Phase Four, we build propulsion systems in runs on a planned production schedule. This allows customers to sign up for units as long as the production run has not commenced, reducing lead times to as short as 3-4 months. We aim for 3-4 production runs per year and each run is comprised of assembly, checkout, and acceptance testing. Take a look at our production schedule below to plan ordering your next Maxwell propulsion system.


Production Run 3 Status

Unit 1
Unit 2
Unit 3
Unit 4
Contact sales

Production Run 2

  • Number of units: 3
  • Unit type: Maxwell Block 1
  • Kickoff: February 2021
  • Deliveries: May 2021

Production Run 3

  • Number of units: 4
  • Unit type: Maxwell Block 1
  • Kickoff: June 2021
  • Deliveries: October 2021

Production Run 4 – Block 2 Pilot

  • Number of units: Up to 5
  • Unit type: Maxwell Block 2
  • Kickoff: February 2022
  • Deliveries: April 2022

Production Run 5

  • Number of units: Up to 10
  • Unit type: Maxwell Block 2+
  • Kickoff: June 2022
  • Deliveries: August 2022


At Phase Four we perform assembly, integration, and test of Maxwell systems 100% in house, and we are gradually on ramping production machining and fabrication. This allows us to control quality and schedule by running production around the clock in our own facilities.