Program Development The Haas 2C SSTO project started in 2012, financed by private companies, being equipped with a liquid oxygen and kerosene turbopump fed system and with a “classic” bell-shape nozzle. The team encountered problems with the very low throttling ability of the liquid oxygen and kerosene combination with the turbopump-fed engine. At the US location we decided to incorporate new technologies, like the pressure-fed, multi-chamber, linear aerospike engine, and the use of the hydrogen peroxide and kerosene combination into the Haas 2CA SSTO. This allowed us to create an engine with a high throttleable range and an overall more cost-effective and efficient vehicle. Since the successful development of the Launch Assist System, ARCA is committed to build an orbital launcher as clean as possible. For the first orbital flight, the Haas 2CA rocket weighting more than 16 tons at launch, will use the LAS 25R as first stage, reducing it’s polluting propellant mass from 16 to only 4 tons.