Apollo Fusion

Apollo Fusion is a Sunnyvale, California Hall-effect thruster developer founded in 2016 that was acquired by Astra Space in 2021 for approximately $145M in stock — representing Astra's strategic bet that manufacturing and selling electric propulsion systems could be a more reliable business than launch, given the challenges Astra was experiencing with its small rocket. Apollo Fusion's signature product is the Apollo Constellation Engine (ACE), a compact Hall-effect thruster optimized for the power levels (200W-1,500W) available on small and medium commercial satellites in the 100-1,000 kg class, producing thrust in the millinewton to tens of millinewton range with Isp of approximately 1,400-1,800 seconds — far more propellant-efficient than chemical cold gas or monopropellant alternatives used on smallsats, enabling significant delta-V capability within satellite mass and volume constraints. The ACE system includes the thruster, xenon or krypton propellant management assembly, and power processing unit (PPU) in an integrated package targeting the constellation satellite market, where hundreds of satellites require cost-competitive propulsion for orbit raising from rideshare deployment altitudes and end-of-life deorbit. Following Astra's pivot away from launch vehicles in 2023, Astra has continued operating Apollo Fusion's propulsion business as its primary commercial activity, supplying thrusters to satellite manufacturers and operating Astra Spacecraft Engines. The company competes with Exotrail (France), Enpulsion (Austria), Busek Company, and Safran Spacecraft Propulsion in the high-demand smallsat and medium satellite electric propulsion market.