Trace missions and inheritance

H-II made seven launches between 1994 and 1999. The dated Japanese launch register lists vehicles 1, 2, 3, 4, 6, 5 and 8 in chronological order. Vehicle 7 was cancelled. A flight identifier therefore does not always tell you how many launches have occurred. Read the event dates alongside the labels.

The COMETS launch is a useful source-checking example. JAXA’s English overview table labels it 7F, but the same page’s prose, the Japanese launch table and the COMETS mission record identify Flight 5. This course follows those mutually consistent records. An official source can contain an editorial mistake; resolving it requires comparison of specific evidence.

Flight 6 carried TRMM and ETS-VII. NASA dates the TRMM launch November 27, 1997 in UTC; JAXA’s local record is November 28 in Japan. These describe the same launch across a time-zone boundary. TRMM was a joint Japanese–American mission measuring tropical and subtropical rainfall, and its scientific operation continued well beyond H-II’s last flight.

For an original time-zone exercise, a launch at 21:30 UTC on November 27 occurs at 06:30 JST on November 28 because Japan is nine hours ahead of UTC. The changed date is not a second launch. Always check a timestamp’s zone before treating a one-day difference as a contradiction.

H-II’s two late failures ended its flight campaign, but its development fed into H-IIA. That later program had its own hardware changes, verification work and operating record. Sharing a technical lineage does not make two programs interchangeable.

A balanced history can recognize three things together: the capability demonstrated, the delivery failures that occurred, and the engineering work carried forward. Continue to the H-IIA course for its operating model and flight evidence, or to Earth-observation courses for the science enabled by missions such as TRMM. The original Japanese launch-family introduction remains available as a shorter orientation.