This segment covers the period from 8 December 2019 to 14 March 2020 (before the eclipse season as well as majority of time during eclipse season) and has 130% data volume as a baseline, however telemetry rate was increased in some orbits above baseline value. For the eclipse season the payload will be off, preliminary times are: on SC3 and SC4 - 24/02/2020 01:30 - 15/03/2020 12:30 and on SC1 and SC2 - 24/02/2020 01:30 -17/03/2020 19:20.

This segment includes a moon eclipse on C1, C3 and C4 on 24 January 2020, on C4 during the period 14:23 - 15:00; on C1 during the period 15:05 - 15:16; on C3 during the period 15:28-16:00, and the science operations will cease for several hours around eclipse times, due to lack of power. Exact time of power off TBD.

There are manoeuvres on C1 and C3 on 10/12/2019; on C1 and C3 on 19/12/2019; on C1 on 08/01/2020; on C1, C2 and C3 on 19/01/2020, and on C1, C2 and C3 on 31/01/2019, for more information ​http://jsocwiki.rl.ac.uk/attachment/wiki/WikiStart/manoeuvres_dec2019-may2020.pdf.

The primary BM1 science targets are the northern high-altitude cusp, GI cusp, cusp with EISCAT, and conjunctions between Cluster, MMS and/or THEMIS at the magnetopause, bow shock and inside magnetosheath.