Thirteen years have passed since the United States introduced a new medium‑lift launch vehicle, the Antares rocket built by Orbital Sciences Corporation. The first version, known as the 100 series, proved problematic from the start. It relied on Soviet‑origin engines that dated back to the era of Apollo moon landings. In the 1990s, Aerojet purchased those engines and refurbished them for a rocket that would not fly until the 2010s. Unsurprisingly, the fifth Antares launch in 2014 ended in an explosion.
Antares now stands as the last example of a shrinking class of American medium‑lift rockets, defined as capable of delivering 2 to 20 metric tons to orbit. Nearly fifteen years later, a new generation of medium‑lift vehicles is entering service, and they differ sharply from Antares. The newcomers use domestically produced engines and core stages, eliminating the reliance on Russian engines and Ukrainian‑manufactured structures that characterized the older system.