Active array antennas have very attractive features but are quite complex and expensive. For this reason, they are today considered for space missions essentially when in flight beam reconfigurability or inertialess beam steering is required. However, array antennas may find wider applications in new potential LEO or MEO telecommunication constellations or as a way to generate very large space aperture thanks to digital processing. The paper presents an overview on the European ongoing activities on active phased arrays with a particular emphasis on the main limitations, challenges, possible improvements and opportunities.