Current status and science operations plan of BepiColombo MMO

BepiColombo is an ESA-JAXA joint mission to Mercury with the aim to understand the process of planetary formation and evolution as well as to understand similarities and differences between the magnetospheres of Mercury and Earth. The baseline mission consists of two spacecraft, i.e. the Mercury Planetary Orbiter (MPO) and the Mercury Magnetospheric Orbiter (MMO). The two orbiters will be launched in 2018 by an Ariane-5 and arrive at Mercury in 2024. Being a spin-stabilized spacecraft, MMO has much less constraint for plasma observations and is expected to extract essential elements of space plasma physics that become visible in the Hermean environment. JAXA is responsible for the development and operations of MMO, and it's almost ready for launch. Therefore, now we can concentrate on preparing the science operations plans. MMO has large constraints on science operations, such as thermal issue and limited telemetry rate. Due to the thermal issue each science instrument cannot always be turned on. In addition, due to the low telemetry rate in average, only a part ( 20-30%) of science mission data with high resolution can be downlinked. Therefore, in order to maximize the scientific results and outcomes to be achieved by MMO, we must optimize the science observation and downlink plans in detail. In this paper, we introduce the science objectives, operations strategies and plans of MMO.