“…It is handled as one of the most important hazardous items in safety review. 6) (2) Solution Conventionally, HTV does two descending maneuvers, DSM1 and DSM2, to depart from ISS, and three deorbit maneuvers, DOM1, DOM2 and DOM3 for controlled reentry. In order to change the parking orbit altitude from 5 km to more than 20 km below the ISS, the maneuver plan adds two maneuvers DSM3 and DSM4 after DSM2, as shown in Fig.…”