Trace separate service handovers

JMA’s July 2009 notice planned a transfer of the principal weather-observation role from MTSAT-1R to MTSAT-2. It explicitly said the aeronautical mission would be unaffected. It also described continuing image distribution and environmental-data collection through MTSAT-1R. Moving the main imager role therefore did not mean every function on the earlier spacecraft stopped.

A plan is evidence of an intended arrangement at the time of publication. JMA’s later history records the primary weather handover on July 1, 2010, providing separate evidence that this milestone occurred. When writing a timeline, connect the planning notice to the outcome instead of quietly converting every planned event into a completed one. Retain changes if the actual result differs.

JMA lists the ends of MTSAT-1R and MTSAT-2 meteorological service as December 23, 2015 and March 10, 2017 respectively. ENRI’s dated history puts the start of MTSAT-based MSAS on September 27, 2007, ends use of MTSAT-1R for that service in September 2015 and describes continuation through MTSAT-2. These are service-specific milestones, not interchangeable retirement labels.

The Cabinet Office confirms that SBAS distribution through Michibiki began in April 2020. ENRI identifies the transition to QZS-3 and renewed ground equipment. This continues an augmentation service across a change of spacecraft family. It does not mean the old MTSAT spacecraft became a new Michibiki satellite, or that the end of a weather service was the end of every aviation function.

A handover ledger needs more than one date

An original comparison exercise uses four columns: spacecraft, service, role and date. A fifth evidence column distinguishes a plan, an observed test result and a confirmed operational transition. A row saying MTSAT-2 became the main weather satellite in July 2010 can coexist with a row describing its later navigation-augmentation role. The ledger prevents an ambiguous word such as retired from doing the work of several different facts.

This approach also helps connect courses. The Himawari course follows the weather-observation service across generations; this course examines the combined MTSAT platform and its separate responsibilities; the QZSS topic follows navigation and augmentation architecture. Their subjects overlap at specific spacecraft and services, while their learning goals remain different. Preserve those connections instead of duplicating one broad survey under several program names.