Relativity Space says it has reached an agreement with Iridium to launch six of the company’s next-generation communications satellites.

Each of the Iridium NEXT satellites, which weigh 850kg, will be launched individually on Relativity’s Terran 1 rocket. This means the new Launch Services Agreement will lead to as many as six Terran 1 missions, beginning no earlier than 2023.

This is the fifth launch-service agreement for Relativity, said Tim Ellis, co-founder of the California-based company. “This agreement represents yet another blue chip company to sign up with Relativity,” Ellis said. It demonstrates that the Terran 1, with a potential lift capacity of 1.25 tons to low Earth orbit, fills a “unique” need in the launch market, he said.