SRB-A3
SRB-A3 is JAXA's composite-solid booster motor standardized across the H-IIA/H-IIB families and adapted for Enhanced Epsilon. JAXA records the first SRB-A3 flight on the H-IIB test flight on 2009-09-11 and the high-pressure-burn variant's H-IIA-18 flight on 2010-09-11. The current specification distinguishes high-pressure and long-duration variants: both are 2.5 m in diameter, 15.1 m long, and rated at 283.6 s vacuum specific impulse, with total burn times of 98 s and 116 s respectively. This record uses active for current JAXA technical and configuration documentation without asserting current H-IIA/H-IIB production, and keeps the successor Epsilon S SRB-3 separate.
Identity
- Aliases
- SRB-A3SRB-A3 solid rocket motor
- Domains
- spaceflight
- Identity Level
- variant
- Kind
- solid-rocket-motor
- Name
- SRB-A3
- Status
- active
Details
- Description
- SRB-A3 is JAXA's composite-solid booster motor standardized across the H-IIA/H-IIB families and adapted for Enhanced Epsilon. JAXA records the first SRB-A3 flight on the H-IIB test flight on 2009-09-11 and the high-pressure-burn variant's H-IIA-18 flight on 2010-09-11. The current specification distinguishes high-pressure and long-duration variants: both are 2.5 m in diameter, 15.1 m long, and rated at 283.6 s vacuum specific impulse, with total burn times of 98 s and 116 s respectively. This record uses active for current JAXA technical and configuration documentation without asserting current H-IIA/H-IIB production, and keeps the successor Epsilon S SRB-3 separate.
- Developers
- First Flight Date
- 2009-09-11
- Length M
- 15.1
- Lineage
- Note
- JAXA describes the Epsilon first-stage motor as a slightly modified SRB-A3; the existing SRB-A record is retained as the broader installed booster boundary.
- Related Propulsion System
- Relationship
- direct-derivative-of
- Sources
- Accessed Date
- 2026-08-01
- Note
- JAXA identifies SRB-A3 as Epsilon's first-stage motor and describes its H-IIA/B booster heritage.
- Publisher
- Japan Aerospace Exploration Agency
- Title
- Epsilon User's Manual
- Manufacturers
- Propellants
- solid HTPB composite
- Rocket Specs
- Vacuum Specific Impulse S
- 283.6
Links
- Official Url
- https://www.rocket.jaxa.jp/rocket/engine/srba/
Assets & Meta
- Creation Time
- August 1, 2026 at 16:32:24 UTC
- Updated Time
- August 21, 2026 at 00:23:41 UTC
Other
- Diameter M
- 2.5
- Sources
- Accessed Date
- 2026-08-14
- Note
- JAXA identifies SRB-A3's first flight on H-IIB, common application across H-IIA/H-IIB and Epsilon, two operational burn-mode variants, shared 2.5 m diameter and 15.1 m length, 98 s versus 116 s total burn, 283.6 s vacuum specific impulse, and H-IIA/H-IIB motor counts.
- Publisher
- Japan Aerospace Exploration Agency Space Transportation Technology Directorate
- Title
- SRB-A
- Accessed Date
- 2026-08-14
- Note
- JAXA identifies SRB-A3 as the Epsilon first-stage solid motor and documents its H-IIA/H-IIB booster heritage and solid HTPB propellant.
- Publisher
- Japan Aerospace Exploration Agency
- Title
- Epsilon Launch Vehicle User's Manual
- Accessed Date
- 2026-08-20
- Note
- JAXA's current SRB-A page records the first SRB-A3 flight on the H-IIB test flight on 2009-09-11, the high-pressure-burn SRB-A3 flight on H-IIA-18 on 2010-09-11, the two burn-mode variants, and their shared dimensions and vacuum specific impulse.
- Publisher
- Japan Aerospace Exploration Agency Space Transportation Technology Directorate
- Title
- SRB-A
- Accessed Date
- 2026-08-20
- Note
- JAXA distinguishes the SRB-A used by Enhanced Epsilon from the SRB-3-based first-stage motor planned for Epsilon S.
- Publisher
- Japan Aerospace Exploration Agency Space Transportation Technology Directorate
- Title
- Epsilon