ARTES 3/4 is the ESA-Industry Programme for satellite telecommunication product developments. This time-limited 'Call for Proposals' is for the development of payload and platform products and processes for LEO-based broadband constellations featuring large numbers of satellites (the so-called "megaconstellations"), for which the industrial development plan is to be engaged before Q3 2016. Several of these ventures have emerged recently, two of which involve the European and Canadian industry at satellite prime contractor level. The scope of the proposed activities shall be within the spectrum of activities supported by ARTES 3-4 (development up to qualification of space components, Atlas support for first flight opportunities and in-orbit validation). Essential characteristics of this Call for Proposals are the sharing of funding by ESA and industry/businesses for the development of the products and a requirement for bidders to provide evidence that their product has been short listed or selected by the satellite prime contractor in theprocurement process for at least one eligible megaconstellation."