United Launch Alliance
The Advanced Cryogenic Evolved Stage (ACES) was a proposed liquid oxygen/liquid hydrogen upper-stage from 2005–2020 for use on a number of different launch vehicles produced by Boeing, Lockheed Martin, and after a late-2006 merger, United Launch Alliance (ULA). During the last five years of the program, ACES was proposed for eventual use on the Vulcan space launch vehicle designed by the U.S. company United Launch Alliance. The ACES concept had the objective to improve the on-orbit lifespan of current upper stages.