On November 17, 2020, during the Future of Rockets keynote, ARCA announced the EcoRocket, a two-stage orbital vehicle, with the first stage powered by 100% clean, water-based propellant.
The uprated current EcoRocket involves a three-stage design with the first two stages using the above-mentioned steam propulsion.
The first two stages are designed to reach space on steam-power only, while the third stage that ignites at space altitudes is using conventional “hot” polluting propulsion, similar to what everyone use.