Sirius 13 and Sirius 15

Why it matters

Using the same engine and core in every version lets one factory serve both single small satellites and batches of constellation satellites.

How the technology works

Each version keeps the two-stage Sirius core. Sirius 13 adds two side boosters and Sirius 15 adds four, each booster carrying nine STAR-1 methane engines.

Rated payloads are 800 kg and 1,100 kg to a 500 km sun-synchronous orbit, or 1,020 kg and 1,500 kg to a 50 degree orbit.