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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

Edit ID  5474727 

Craig Peterson
Craig Peterson edited on 10 Sep, 2018
Edits made to:
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 Artist's conception of the Momentus Ardoride Orbital Transfer Vehicle

The next 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.

S-bnad MET Thruster in the Lab.
S-band MET Thruster in the lab.

The above 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.

Why Water?

Choice of propellant is a primary cost driver, due to chemical properties, handling requirements, storage conditions, and many other factors including the following:

  • Safe and Nontoxic to reduce labor facility costs to built and test propulsion systems and eliminates concern of contamination for ride share payloads.
  • Dense and Easy to Store and Handle at Standard Pressure and Temperature - to eliminate the need for high pressure storage and feed system which in turn enhances safety, reduces tankage mass, and reduces orbital debris risk in case of operational mishap.
  • Inexpensive - Although at today’s satellite prices propellant cost itself is typically a small fraction of total system cost. As system cost comes down, today’s expensive propellants will be an unacceptably high fraction of total system cost.
  • High in Low Atomic Mass Elements as is needed to serve as effective radiation shielding material to allow for synergy in structure design by using the propellant storage tank as both structure and shielding, and
  • Available on the asteroids and planetary surfaces as a form of future proofing against eventual in-situ resource utilization technology and as a way to enable, resupply in space from locally available resources.

Based on these criteria, water is the ideal propellant which is why Momentus has chosen to focus on water based MET as their core technology.


WithAs shown in the folling roadmap diagram, 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 ZealTM and VigorTM 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 ArdorideTM and VigorideTM SmallSat space tugs. By 2021 they plan to be ready with FervorideTM which is a high performance space tug designed deliver a new generation of GEO sats. Their roadmap culminates in ValorideTM a large scale space tug designed to support space manufacturing, asteroid mining and resupply for space hotels. ValorideTM will be the workhorse transportation service that ferries equipment and supplies throughout cislunar space and between LEO, GEO, and the asteroids.


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