SAN FRANCISCO – Silicon Valley startup Momentus’ is reporting success in on-orbit testing of water plasma propulsion and other key elements of its Vigoride in-space transportation vehicle.

“The on-orbit testing has demonstrated for the first time that microwave electrothermal plasma technology has the potential to achieve high specific impulse using water propellant,” Momentus CEO Mikhail Kokorich told SpaceNews. “Water plasma propulsion is now technologically mature enough to be baselined for operational in-space transportation missions.”

For the next few months, Momentus plans to continue firing the water plasma thruster and performing in-space maneuvers on the El Camino Real spacecraft launched in July. Engineers will compare the results of on-orbit testing with results of ground tests to validate the company’s models and analysis, Kokorich said by email. El Camino Real is a 16-unit cubesat integrated by Astro Digital, a spacecraft manufacturer and geospatial data analysis firm based in Santa Clara, California.

Momentus has raised more than $34 million for its campaign to develop Vigoride and Vigoride Extended, shuttles to move small satellites between orbits. One promising application for the technology is moving satellites from the orbit where they are dropped off by large rockets conducting rideshare missions to their optimal orbital locations, Negar Feher, Momentus product and business development vice president, said at the World Satellite Business Week conference in Paris earlier this month.

“The purpose of the El Camino Real mission was to flight demonstrate our core propulsion technology so customers, investors and stakeholders can have absolute confidence that Momentus will deliver their payloads to a given orbit,” Kokorich said. “Some early results have already been shared with our stakeholders, which include customers,” he added.

In addition to water plasma propulsion, Momentus is testing Vigoride subsystems on the El Camino Real mission including flight software, avionics, attitude sensors, microwave and power system. During the mission, Momentus has noted both nominal and off-nominal operational events “as can be expected from any new flight system,” Kokorich said.

During one operation, water froze throughout the spacecraft’s propulsion lines. “The system proved to be highly resilient and post-freezing, all units were successfully verified to operate as expected,” Kokorich said. “El Camino Real has performed numerous hot thruster firings on-orbit since it launched in early July and the company has collected a wealth of valuable telemetry.”

Momentus revealed the first El Camino Real test results on Twitter. “El Camino Real is performing as expected!” the company tweeted Sept. 9. “This successfully demonstrates for the first time in-space water plasma propulsion, and also demonstrates the technology, which has the highest specific impulse among other water-based propulsion.”