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