Momentus tug raises orbit with water-fueled thruster
WASHINGTON — Momentus announced May 8 that it has successfully demonstrated the propulsion system on its Vigoride space tug, raising the vehicle’s orbit.
The company said that the Microwave Electrothermal Thruster (MET) on its Vigoride-5 vehicle, successfully test-fired in March, has since fired more than 35 times of varying durations. That has been sufficient to counteract drag and raise the vehicle’s orbit.
“This initial orbital raise was a key goal of our Vigoride-5 mission and the MET’s performance has exceeded our expectations,” Rob Schwarz, chief technology officer of Momentus, said in a statement. “We have now operated the MET successfully in space at full power across the range of durations for firing that we plan to use operationally to deliver satellites to precise, custom orbits and to provide in-space infrastructure services like hosted payloads.”
The MET, which vaporizes water with microwaves to generate thrust, has fired for more than 140 minutes cumulatively, in burns ranging from 30 seconds to six minutes each. The company said that those burns raised the orbit of Vigoride-5 by more than three kilometers when taking atmospheric drag into account.
According to tracking data, Vigoride-5 is in an orbit at an average altitude of 524.3 kilometers as of late May 7, about two kilometers higher than it was in early April, when the maneuvers started. The vehicle’s orbit had been gradually decaying since its launch in early January on the SpaceX Transporter-6 smallsat rideshare mission, descending about five kilometers before the maneuvers started.
The test of the MET is a major milestone for Momentus, which is relying on the technology to propel its tugs that will deliver satellites to their desired orbits. Technical problems with its first tug, Vigoride-3, launched nearly a year ago, kept the company from testing the MET on that vehicle.
Vigoride-5 is carrying a single smallsat, for Singapore-based Qosmosys, that it will release, although the companies have not disclosed the planned orbit for that spacecraft. The tug will also operate a hosted payload from Caltech to demonstrate space-based solar power technologies for several months.
Momentus has since launched a third vehicle, Vigoride-6, on SpaceX’s Transporter-7 mission April 15. That tug, carrying a pair of NASA cubesats among several other payloads, is still going through post-launch commissioning.
The company argues that the MET can operate at higher efficiencies than chemical propulsion systems while generating more thrust than typical electric propulsion systems. Using water avoids the cost and handling issues associated with other propellants and creates the potential, in the long term, to refuel MET-powered spacecraft with water extracted from the moon or asteroids.
The Vigoride-5 announcement comes ahead of the release of the company’s quarterly earnings, scheduled for after the markets close May 11. The company reported a net loss of $91.3 million in 2022 but said in a March 7 earnings call it had sufficient reserves to meet its needs for the next year.