Read a completed flight record

MHI records nine successful H-I launches between 1986 and 1992. JAXA’s historical vehicle list gives the same operating span. The final flight launched Fuyo 1, also called JERS-1, on February 11, 1992. The dated satellite record resolves an inconsistent 1991 endpoint in the prose of one H-I overview.

Numbering needs similar care. H15F and H24F appear in the historical H-I table, but they do not mean the fifteenth and twenty-fourth H-I launches. Treat a flight identifier as an identifier until its numbering convention is established; count the actual entries and check their spacecraft and dates.

A completed run of successful launches is valuable evidence about the actual program. It is not proof that failure was impossible or that an unflown modification would have performed identically. Test results, manufacturing controls, operating conditions and the number of opportunities all affect what can be inferred.

Consider an original probability exercise, unrelated to an estimate of H-I reliability: a hypothetical device has a 90% chance of success on each independent trial. Nine successes in a row have probability 0.9 multiplied by itself nine times, about 39%. A short perfect record can occur even when the underlying chance is below 100%.

Keep three histories distinct

Fuyo 1 combined radar and optical observation. JAXA reports more than six years of observations despite a two-year design life, with the mission ending in October 1998. Those are spacecraft-service results; the launch vehicle did not remain attached and provide propulsion throughout that observing period.

H-I’s contribution also continued through engineering knowledge used in H-II. Distinguish three timelines: the launcher’s flight campaign, the spacecraft’s service and the later use of related technology. Keeping them separate produces a more informative history than assigning one end date to everything associated with the program.