[4][5][clarification needed] By 2010, ULA had inherited the intellectual property of both proposals, and the ACES concept had evolved into a new high-performance upper stage to be used on both Atlas V and Delta IV/Delta IV Heavy launch vehicles.
[3] As of April 2015[update], ACES was expected by ULA to debut on the Vulcan launch vehicle no earlier than 2023[7] but in July 2015 the timeframe was clarified to not likely fly until 2024–2025.
[9] ACES was planned to use ULA's proprietary Integrated Vehicle Fluids (IVF) technology to significantly extend its lifetime in space.
[11] In late 2017, ULA decided to bring the 5.4 m (18 ft) diameter and advanced insulation elements of the ACES upper stage forward.
[12] On 11 May 2018, United Launch Alliance (ULA) announced that the Aerojet Rocketdyne RL10 engine was selected for Centaur V, following a competitive procurement process.
[17] One potential application for ACES was stated by ULA in 2010 to be the use of the longer endurance and the greater fuel capacity as propellant depot with in-space refueling capability to retrieve derelict objects for near-space clean up and deorbit.