Separate launch and mission outcomes

M-V made seven launch attempts, of which six succeeded. Its successful-mission table lists six spacecraft, so counting those rows alone would omit the failed attempt. A summary must define its denominator: launch attempts, successful deliveries and completed spacecraft missions are different quantities.

ASTRO-E was lost after a first-stage malfunction during its February 10, 2000 launch. NASA HEASARC’s account explains that the spacecraft did not reach a usable orbit. The initial ISAS report is explicitly preliminary. Use its observations as contemporary evidence, while keeping an initial explanation separate from any later investigation conclusion.

Nozomi launched on M-V in 1998, but its attempt to become a Mars orbiter was abandoned in December 2003 after spacecraft problems. It nevertheless returned some interplanetary observations. Describing only a launch success would hide the unachieved Mars-orbit objective; describing only a failed Mars mission would hide both the launch result and the data that were obtained.

A useful mission record has separate fields for launch delivery, spacecraft health, arrival or orbit insertion, and scientific results. A successful entry in one field does not automatically fill the others. This distinction also helps compare a telescope, a planetary probe and a technology demonstration fairly.

For a simple historical fraction, six successes divided by seven attempts is about 85.7 percent. This is a description of that recorded sample, not a guarantee for an eighth flight. Changes to hardware, operations or mission requirements can affect whether past results apply to a new proposal.

M-V’s last launch carried Hinode in September 2006. Epsilon followed as a separate solid-launcher development program. The end of one vehicle’s service is not the end of the engineering knowledge it produced. Preserve the specific flight outcomes and design lessons when studying how a successor changed its goals.