On 15 April the Proba-V minisatellite secured to its Small Satellite Interface System (SISS) was lowered onto the Vespa - Vega Secondary Payload Adapter - containing its fellow passengers, Vietnam’s VNREDSat Earth observation mission and Estonia’s ESTCube-1 student nanosatellite, to test electric solar sail technology. Proba-V will make the journey into orbit on board ESA's Vega launcher, flight VV02, in May 2013.