Water Plasma Drives

Momentus Space promises Orbital Transfer services via microwave heated water plasma drives hooked up to an autonomous navigation & power unit. Essentially they trim the orbit for payloads delivered to LEO via services like the Falcon, Falcon 9 and the Starship.

LEO orbit raisingMain propulsion for small spacecrafts
LEO constellation deploymentOrbit raising from LEO, orbit inclination change
SSO orbit plane adjustmentSatellite deorbiting missions
De-orbitingMain thruster for deep space spacecrafts
In-space boosters for micro-launchers
Wet Mass (without Payload): 80 kgWet Mass (without Payload): 450 kg
Maximum Payload Mass: 250 kgMaximum Payload Mass: 300 kg
Total Impulse: >100,000 N-sTotal Impulse: >1,500,000 N-s
Maximum ?V: >1 km/s for 50 kg payloadMaximum ?V: >5 km/s for 100 kg payload
Boosting of large satellites from LEO to GEOWater delivery from asteroids to cis-lunar space
Moon exploration resupplyWater bunkering
Deep space missionsDeployment of asteroid mining infrastructure
Asteroid mining infrastructureMoon and Mars exploitation resupply
Payload: >10,000kg to GEOPayload: >100,000 kg
?V: up to 8km/sec
Propulsion: water plasma-powered Fervor™Propulsion: water plasma-powered Valor™
Specific impulse: 900 secSpecific impulse: 1100 sec
Solar power: >10kWSolar power: >100kW

While I’m not 100% sure of the specific technology a similar concept is the Helicon Thruster – named for the antenna which uses radio-frequency energy to heat water to plasma temperatures, all without actually contacting the super-corrosive ultra-hot steam. Most helicon thrusters encapsulate the “reaction chamber” in a quartz tube.

Electric propulsion is inherently low thrust as the energy in the jet must be supplied by a power source. Solar panels can only be so light and are inherently huge when a long way from the sun.