Momentus is an early-stage U.S. space company that builds and operates Orbital Service Vehicles (OSVs) and satellite buses, targeting government agencies, defense customers, and commercial satellite operators. Momentus' core product is the Vigoride OSV — a spacecraft that rides to orbit aboard a launch vehicle (typically SpaceX's Falcon 9 via rideshare), then acts as a last-mile delivery vehicle, transporting small customer satellites from the rocket's drop-off orbit to their precise final orbit. Beyond transportation, Momentus offers hosted payload services, renting space on its OSV to customers who want to operate or test hardware in orbit without building and launching a full satellite. Momentus also sells satellite buses and full satellites (the M-500 and M-1000 variants) for applications like communications, missile tracking, remote sensing, and space domain awareness. Revenue comes from space transportation contracts, hosted payload slots, satellite hardware sales, and government R&D contracts. Key costs include purchasing rideshare launch capacity, vehicle manufacturing, and R&D. Vigoride OSVs are currently expendable — used once and de-orbited — which limits margins; reusable OSVs are a longer-term goal to improve unit economics. Momentus uses a water-propellant Microwave Electrothermal Thruster (MET), which the company argues reduces handling costs versus toxic propellants. The company has completed four missions and deployed 17 customer satellites, with 35 employees as of early 2026. Growth priorities include developing reusable OSVs, expanding into higher orbits, and building RPO (rendezvous and proximity operations) capabilities to enable in-orbit servicing markets.