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, the eclipse times are: on SC3 and SC4 24/02/2020 12:00 - 15/03/2020 00:00 and on SC1 and SC2 are 24/02/2020 12:00 - 17/03/2020 00:00.

During this eclipse season there were two BM1 requests for the Cluster /MMS conjunctions: (i) 20/03/03 09:30 – 12:00, for 1.5h BM1 mode surrounded by NM1 mode; (ii) 20/03/10 05:40 - 10:20 for 1h NM1 + 2.5h BM1+1h NM1. However these intervals were not accomodated.

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. Due to the different power profiles, the moon eclipse impact for each spacecraft varies. On C1, which is not affected much, there is no constraints on the payload and TDA6 periods, payload will stay on. On C1 the WBD operations are not allowed during the period 24/01/2020 12:00-18:00. On C3, there will be 'Power Limited' platform configuration: with the CIS, PEACE, WEC and FGM instruments being off during the period 24/01/2020 15:00 - 16:30. In addition, there will be no BM1 and BM2 modes allocated during the same interval, and no WBD operations during the interval 24/01/2020 12:00 - 18:00. On C4, all payload will be switched off for the period 24/01/2020 06:00 - 25/01/2020 00:00, there will not be any BM1 and BM2 modes allocated during the period 24/01/2020 00:00 - 25/01/2020 and no WBD operations during the period 24/01/2020 00:00 - 25/01/2020 00:00.

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.

The MSP42.1 was updated on 20/11/2019 in order to accommodate the February 2020 eclipse season start and the moon eclipse in January 2020.