IHI Aerospace

IHI Aerospace Co., Ltd. is Japan's primary solid rocket motor manufacturer and a critical component of JAXA's launch vehicle propulsion supply chain, established in 1960 as the aerospace division of Ishikawajima Harima Heavy Industries (IHI Corporation) and formally spun off as a dedicated subsidiary in 2003. The company supplies the solid propulsion systems for both of JAXA's primary orbital rocket families and has been central to Japanese rocketry since the early days of ISAS's pencil-rocket sounding vehicle programs.

For the Epsilon solid orbital rocket — JAXA's science satellite launcher currently flying in its Epsilon-S upgraded configuration — IHI Aerospace manufactures the complete solid motor stack: the M-35 first stage motor (the largest element, providing the majority of the vehicle's total impulse), the M-34c second stage motor, and the KM-V2b third stage motor, representing virtually the entire propulsive system of a vehicle designed for autonomous launch operations with minimal ground control staffing. IHI's motor quality and reliability underpins JAXA's ambitious goal of a nearly automated launch process.

For the H-series liquid rocket family — H-IIA, H-IIB (now retired), and the new H3 — IHI Aerospace manufactures the Solid Rocket Boosters (SRBs) that provide critical additional thrust at liftoff: the SRB-A and SRB-3 variants strap onto the H-IIA and H3 core stages respectively, enabling the heavy-payload configuration needed for GTO launches of commercial and government telecommunications satellites. Two or four SRBs can be attached to H-IIA to tune the payload capacity.

IHI Aerospace also contributes to liquid propulsion: IHI Group's aerospace division participates in the turbopump manufacturing for JAXA's LE-7A engine (H-IIA/B) and the new LE-9 engine (H3), bridging solid and liquid propulsion expertise. Historical heritage includes contributions to ISAS's M-series solid rocket motors culminating in the M-V (Mu Five), Japan's largest solid rocket capable of 1.8 tonnes to LEO, which flew from 1997-2006 carrying landmark science missions including Hayabusa asteroid sample return. Domestically IHI competes and collaborates with Nissan's historical aerospace division and Daicel Corporation for propellant chemistry.