Russian rocket-builder Energomash is developing a liquid rocket engine fueled by a mixture of acetylene and ammonia, called atsetam, which the company says will dramatically reduce launch costs.
The atsetam-fueled upper stage engines will be modified from RD-161s. RD-161 is a small, single-chamber engine developed for the third stage of the cancelled Rus launch vehicle and never flown.
The first engines will be ready to launch in 2017, says Energomash, though the company did not mention which launch vehicle the engine will be integration onto.
Many liquid engines currently use a standard mixture known as rocket propellant-1 (RP-1), a refined form of kerosene. While the mixture contains a high energy content, allowing high efficiency, it is very expensive to procure and store.
While atsetam may be significantly cheaper to purchase, fuel costs are a relatively small fraction of overall launch costs for disposable rockets. Several launch providers are working towards reusable launch vehicles, which show potential to significantly reduce launch costs.