Maintain a regional view

Himawari is Japan’s long-running geostationary weather-satellite series. Its orbit keeps a broadly fixed view relative to Earth, allowing repeated observations of the same region. That makes it useful for following a changing cloud system. A satellite repeatedly passing over different ground tracks offers a different observation pattern; neither pattern answers every question equally well.

Imagine monitoring a storm crossing an ocean. One sharp image locates its visible cloud structure at one time. Repeated images reveal how that structure changes. The useful service includes the spacecraft, instruments, ground processing and delivery of observations to forecasters; placing hardware in orbit is only one part of it.

The first GMS satellite launched on July 14, 1977; full operation began on April 6, 1978. Himawari-8 launched on October 7, 2014 and entered service on July 7, 2015. These paired milestones distinguish reaching space from commissioning an observation service. They should not be collapsed into one date.

Himawari-9 launched on November 2, 2016 and later served as backup before becoming the primary satellite on December 13, 2022. This is a dated handover, not a live statement about today’s instrument availability. A reliable history records changes of responsibility as well as launches.

Follow the service through distinct milestones

Himawari 3, also called GMS-3, contributed observations during an earlier generation of the service. The linked archive card identifies that particular spacecraft. Its cyclone image can be compared with the later Himawari-9 full-disc observation as two examples from the program, while retaining their different dates, instruments and processing histories.

MTSAT also supplied meteorological observations within this history, but it was a distinct dual-purpose program with aviation responsibilities. Following its weather contribution here does not explain its whole mission. This is why related courses and spacecraft cards remain separate: a shared service can connect programs without making their goals identical.