The acronym ZEpHyR stands for „ZARM Experimental Hybrid Rocket“. The goal of this scientific project is to develop a hybrid rocket motor which utilizes liquid oxygen as oxidizer and paraffin (candle wax) as fuel. The advantage of this kind of hybrid rocket motors is that they are environmentally friendly and safer than other rocket motors, which are using hazardous and potentially high-explosive fuels. The successful launch of ZEpHyR 1 in April 2016 from ESRANGE Space Center in northern Sweden has proven the proper functionality of the rocket motor and provided important data for further development of the rocket systems. Since then the concept is being enhanced and optimized with the goal of ZEpHyR 2 to be launched in 2020.

The ZEpHyR 2 rocket is an enhancement of the ZEpHyR 1. The preliminary design has a diameter of 0.3 metres and a length of 5 metres. Due to the higher mass of the rocket the motor has more thrust of up to 5000 N. ZEpHyR 2 will use a pressure regulated feed system with helium as pressurisation gas. The main challenges of the ZEpHyR 2 development will be the upscaling of the hybrid rocket motor, the optimisation of its efficiency, the reduction of the structural mass and the design of the recovery system.

ZEpHyR is the contribution of the ZARM Institute to the STERN programme (Student Experimental Rockets) of the German Space Administration (DLR), which enables students to design, build and launch sounding rockets. The main goal of this programme is the education of students to prepare them for future employments in the space industry and giving students the opportunity to run through a complete space project cycle with space industries standards.