“The Merlin 1D successfully performed every test throughout this extremely rigorous qualification program,” SpaceX CEO and Chief Designer Elon Musk said in a statement. “With flight qualification now complete, we look forward to flying the first Merlin 1D engines on Falcon 9’s Flight 6 this year.”

       SpaceX’s testing program demonstrated a ratio of 4:1 for critical engine life parameters, with an industry standard of 2:1. The Merlin 1D’s vacuum thrust-to-weight ratio exceeds 150, making the Merlin 1D the most efficient booster engine ever built while also maintaining the thermal and structural safety margins to carry astronauts. The engine uses higher efficiency processes, increased robotic construction and reduced parts count, therefore improving manufacturability.