An unpiloted space plane developed by Sierra Nevada Corp. will join cargo carriers built by SpaceX and Orbital ATK to resupply the International Space Station beginning in 2019, NASA announced Thursday.

A second unpiloted test flight of Boeing’s Starliner crew capsule — ordered after an initial demonstration mission fell short of reaching the International Space Station — is now scheduled for launch from Cape Canaveral in August or September, leaving little margin to conduct the spaceship’s first flight with astronauts before the end of the year.

Four satellites tucked inside the tip of a Soyuz rocket lifted off Thursday, heading for a 5,000-mile-high orbit to expand the reach of O3b’s broadband communications network. Liftoff from the European-run spaceport in French Guiana occurred at 1:37 p.m. EST (1837 GMT).