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For the last three years the European deep-space optical communications program had been based on the Asteroid Impact Missions (AIM), a rendezvous mission with the double-Asteroid Didymos. Unfortunately, the AIM mission was not approved by ESA council and efforts are now concentrated on the implementation of a Deep-space Optical Communication System (DOCS) in a Space Weather (SWE) mission to libration orbit L5 within the frame of ESA’s Space Situational Awareness (SSA) program. DOCS is an in-orbit technology demonstration that also serves a scientific objective, namely the transfer of high-resolution solar imagery. The characteristics of the SWE L5 mission allow significant simplifications in deep-space optical communication terminal design, because the equidistant triangular orbital geometry between the sun, the Earth and L5 (all three distances are 1 AU = 150 Mio km) ensures that the sun is always separated by 60 degrees from both, the space and the ground terminal. This allows for very efficient solar stray-light shielding and thermal management. It also minimizes the pointing requirements of the DOCS space terminal; a coarse pointing mechanism is not required, nor is a point ahead mechanism. The SSA SWE L5 mission Phase A, Phase B1 and B2 studies will be conducted 2017 - 2019. DOCS aims to demonstrate a data rate of 10 Mbps over 150 Mio km to a 4 m optical ground station. The paper will give an overview of deep-space optical communication technology developments and present the design and performance of the Deep-space Optical Communication System (DOCS).
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