A combination of solar power, microwaves, and distilled water has managed to lift Momentus Space’s Vigoride-5 spacecraft thousands of feet above its original orbit, in what is a critical milestone for the California-based startup.
The orbital raise was made possible by the company’s Microwave Electrothermal Thruster (MET), which uses distilled water as propellant. Momentus said in a May 8 press release that the MET system lifted the company’s Vigoride-5 orbital transfer vehicle more than 3 kilometres during the recent demonstration.
“This initial orbital raise was a key goal of our Vigoride-5 mission and the MET’s performance has exceeded our expectations,” Momentus Chief Technology Officer Rob Schwarz said in the release. “Each ignition has been successful, and we’ve completed more than 35 firings ranging from 30 seconds up to six minutes in duration, which is what we plan to use operationally. Cumulatively, we have accomplished over 140 minutes of firing time of the MET system.”
Rockets don’t always deliver satellites to their target orbits, requiring the use of space tugs to finish the job. Founded by Russian entrepreneur Mikhail Kokorich, Momentus is seeking to provide this exact orbital transportation service, among other in-space infrastructure services, to paying customers.
For the latest demo, Momentus tested MET under conditions needed for operational missions, including full power thrusts and thrusts performed across the anticipated durations. The system operated as intended, and the company now looks forward to “using it to support commercial and U.S. Government customers,” said Schwarz.
Conventional space tugs use rocket engines that rely on chemical reactions to heat propellant. The MET system differs in that solar-powered microwaves serve as the onboard energy source for generating the required hot plasma, heating the propellant to produce thrust.
The company says non-toxic water propellant results in simpler, safer, and more cost-effective operations, whether in Earth orbit or elsewhere, as water is readily available on the Moon, asteroids, and other planets. What’s more, MET “can provide future missions with higher efficiency than chemical propulsion systems and higher thrust than electric propulsion systems,” Chris Kinman, Momentus chief commercial officer, explained in the press release.
The company has launched three Vigoride Orbital Service Vehicles to space in less than one year. The inaugural mission, launched in May 2022, experienced multiple issues shortly after launch but still managed to deploy several payloads. In January, Vigoride-5 launched to space via SpaceX’s Transporter-6 smallsat rideshare mission, which in turn deployed the tiny Qosmosys Zeus-1 satellite. Vigoride-6, launched in April with payloads belonging to NASA and commercial customers on board, and is still in the commissioning phase.