WASHINGTON — Electric propulsion company Phase Four flew its first plasma thrusters on two spacecraft that were part of a SpaceX dedicated rideshare launch Jan. 24.

Phase Four said its Maxwell plasma propulsion systems were on two of the 143 spacecraft launched on the Transporter-1 mission. The company declined to name the satellites at the request of its customer, which is flying an operational mission but is also testing other new designs on those spacecraft.

The thrusters on those two satellites are the first developed by Phase Four, founded in 2015, to fly in space. In an interview, Beau Jarvis, chief executive of the company, said the company eschewed an approach of quickly building and flying a technology demonstration and then raising money to build a commercial model.