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Momentus Space

Momentus Space

Momentus is a YC Summer 2018 batch company developing the in-space rockets powered by water plasma engines and based in Santa Clara, CA

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Craig Peterson edited on 10 Sep, 2018
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Momentus is developing the in-space rockets powered by water plasma engines and based in Santa Clara, CA

Founded by space entrepreneur Mikhail Kokorich and his partner Lev Khasis in Santa Clara in 2017, Momentus was born out of countless discussions with satellite operators seeking more affordable in space transportation. Momentus is developing in-space propulsion systems powered by microwave electro-thermal (MET) water plasma engines. Momentus Space is the first in-space transportation services company build around high performance water plasma rocket propulsion. Momentus’ water plasma propulsions systems are more efficient and faster than the solutions of the past, but more important, they are far more affordable because water is cheap, non-toxic, safe, and easy to work with. Even more important in the the long term, water based propulsion is utterly future proof and provides a clear path to breaking the ties of space industries to the Earth by allowing easy resupply from the most plentiful resources of space, the asteroids for the time when asteroid mining emerges as a major new industry.

Microwave Elctro-Thermal Propulsion

Based on over 30 years of university research funded by NASA and the US Air Force enhanced by several new patent pending Momentus innovations, Momentus Space’ new microwave electrothermal water propulsion systems use as little as one third the propellant as chemical propulsion systems while delivering payloads as much as three times faster than old school solar electric ion propulsion.

METs are plasma-based electrothermal devices that use Joule heating of a partially ionized gas to heat un-ionized propellant which is then ejected through a converging-diverging nozzle to create thrust in the same manner as chemical rockets. The thruster body itself is a microwave resonant cavity that allows for microwave breakdown of virtually any gas-state propellant. Momentus is specifically developing an MET system that uses water as the propellant in a highly localized region just upstream of the rocket throat. A combination of solar array power and batteries (depending on duty cycle) provides the energy necessary for operation. For thier high power systems the microwave power to drive the system is generated by magnetrons, which are the highest efficiency means of producing radiation from electric power and are highly mature in the terrestrial food preparation and materials processing industries.

Previous academic research and their own in-house development efforts have shown that by carefully injecting the propellant gas with vortex inducing swirl, the gas discharge can be confined on centerline, where the microwave intensity is greatest, thereby inducing a strong radial profile in the gas temperature. Electron temperatures on centerline in the discharge can be as high as 15,000 to 20,000 Kelvin allowing heating of the centerline gas to several thousand Kelvin while the boundary layer temperature of the gas that is in contact with the thruster throat can be within the long life temperature constrains of refractory metals.

Our expert analysis and review of extant literature suggests that at achievable temperatures, specific impulse can approach 1,000 s due to extremely high survivable bulk gas temperature and thermal dissociation of the water molecules to the atomic state. Rocket propulsion technologists will be interested in Figure 6 which shows how molecular dissociation of water serves to increase specific impulse at a given temperature beyond that which would be expected at 18 gImol for water by reducing the average molecular weight.

Key Design Fearutres of a Microvwave Electro-Thermal (MET) Thruster showing the TM001 Mode Field Patterna in the Resonant Cavity.  This caviz

The following figure shows a plot of frozen flow, fractional dissociation, and thermal efficiency versus chamber temperature for an expansion ratio of 100:1 with water propellant as modeled in TDK, a two-dimensional kinetic code maintained by Sierra Engineering for combustion simulation. An 8,000 K chamber temperature, which is not unreasonable given data in the literature, yields a specific impulse of about 750 s.

Specific impulse (frozen flow), fractional disassociation, and chamber enthalpy to jet efficiency versus temperature for water propellant with an expansion ration of 100.

Figure shows an image of an S-Band (2.45 GHz) MET operating in the Momentus laboratory using water propellant at a power Level of 3 kW

Products and Services

With their first orbital flight demonstration planned to be ready for launch in 2019 Momentus technology roadmap starts with the conservative proven technical approaches of the Zeal™ and Vigor™ technologies that they are quickly adapting for flight. They will be ready to start taking orders for small sat transportation services in Earth orbit for launch as early as 2020 with their Ardoride™ and Vigoride™ SmallSat space tugs. By 2021 they plan to be ready with Fervoride™ which is a high performance space tug designed deliver a new generation of GEO sats. Their roadmap culminates in Valoride™ a large scale space tug designed to support space manufacturing, asteroid mining and resupply for space hotels. Valoride™ will be the workhorse transportation service that ferries equipment and supplies throughout cislunar space and between LEO, GEO, and the asteroids.

Current Roadmap of Momentus Propulsion System and Orbital Transfer Vehicle (OTV)  Development, along with potential applications


Related Golden topics

Joel Sercel

Chairman of Advisory Board

Lev Khasis


Mikhail Kokorich

President and Co-Founder

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