KAIROS
Space One — KAIROS
KAIROS is a Japanese small-satellite orbital launch vehicle built by Space One, using three solid-fuel stages plus a liquid-propellant post-boost stage, launching from Spaceport Kii.
Technical specifications
- Stages
- 4 (3 solid-fuel stages + 1 liquid-propellant post-boost stage)
- Height
- ~18 m
- Diameter
- 1.35 m (body); 1.5 m (fairing)
- Liftoff mass
- ~23,000 kg
- Payload to LEO (500 km, 33°)
- 250 kg
- Payload to SSO (500 km, 97°)
- 150 kg
- Launch site
- Spaceport Kii, Kushimoto, Wakayama Prefecture, Japan
- Manufacturer
- IHI Aerospace (Tomioka Plant, Gunma Prefecture)
- Flight heritage
- 3 launch attempts, 0 successes as of July 2026: Flight 1 (Mar 13, 2024) - flight termination ~5s after liftoff; Flight 2 (Dec 18, 2024) - lost attitude control, terminated; Flight 3 (Mar 4, 2026) - performance anomaly, terminated ~70-100s after liftoff
About
KAIROS (Kii-based Advanced & Instant Rocket System) is a small orbital launch vehicle developed by Space One Co., Ltd., a Japanese consortium formed by Canon Electronics, IHI Aerospace, Shimizu Corporation, and the Development Bank of Japan, manufactured by IHI Aerospace. KAIROS is a 4-stage rocket comprising three solid-fuel propulsion stages plus a liquid-propellant post-boost stage used for precise orbital insertion, standing about 18 meters tall with a 1.35 m body diameter and roughly 23,000 kg liftoff mass. It is designed to carry small satellites to LEO and SSO, targeting a responsive-launch business model. KAIROS launches from Spaceport Kii, Japan’s first privately built orbital spaceport, in Kushimoto, Wakayama Prefecture. Flight heritage has been troubled: Flight 1 (March 13, 2024) was destroyed by its flight termination system 5 seconds after liftoff due to insufficient first-stage thrust. Flight 2 (December 18, 2024) lost attitude control and tumbled during first-stage burn before being terminated. Flight 3 (March 4, 2026) suffered a performance anomaly and was terminated roughly 70-100 seconds after liftoff. As of mid-2026, KAIROS has not achieved a successful orbital launch after three attempts.
Documentation
No public datasheet yet — request the datasheet / ICD from the supplier.