The VENUS study, which has been initiated in mid-2007, is a joint DLR-EADS Astrium effort, funded by the DLR Space Agency, which goal was to study new upper stages for the Vega launch vehicle. In the first step SART analysed 6 different liquid engine options and found the optimum performance for each stage into the VEGA polar reference orbit. EADS-Astrium established a preliminary upper stage architecture including mass balance for some of the most promising configurations. Two concepts were mainly studied during this project which ended in June 2011: a 4 stage launch vehicle and a 3 stage launch vehicle.
The 4 stage launch vehicle is similar to the current Vega launcher design. However Vega P80 solid first stage is replaced by a P100 solid rocket motor, which is seen as an evolution of P80. The current Vega Z23 solid second stage and Vega Z9A solid third stage are reused unchanged. The AVUM (Attitude and Vernier Module) of Vega is replaced by a new storable propellant upper stage, for which the propellant mass and the thrust level have been optimized by the SART group. The engine considered in the frame of this concept is pressure-fed and uses MMH and NTO as propellant.The 3 stage launch vehicle is based on a P100 solid first stage, a Z40 solid second stage, considered as an evolution of the Vega Z23 second stage and a new storable propellant upper stage propelled by the AESTUS II gas generator engine.Both concepts allow an increase of the payload performance compared to the current Vega design, with even more than 2000 kg in the Vega’s reference orbit for the 3 stage configuration.