Jaxa H3

H3 is a Japanese two-stage liquid-propellant launch vehicle using LH2/LOX on both stages, with optional solid rocket boosters, operated by JAXA with Mitsubishi Heavy Industries (MHI) as prime contractor and commercial operator.^[1][2] The vehicle is active as of mid-2026.^[2] The modular configuration system, designated H3-XYZ, varies the number of first-stage engines (2 or 3 LE-9), the number of SRB-3 boosters (0, 2, or 4), and fairing length (short 10.4 m or long 16.4 m), all sharing a 5.27 m fairing diameter.^[2] Representative payload figures: 4,000 kg to SSO (H3-30S configuration)^[2], 6,500 kg to GTO (H3-24)^[2], and 16,500 kg to LEO (H3-24).^[2]

H3 first flew on 2023-03-07; the initial flight (F1) failed due to second-stage ignition failure, with ALOS-3 lost.^[2] The first successful flight was 2024-02-17 (F2).^[3] As of mid-2026 the vehicle has completed 8 flights with 6 successes.^[2] The third flight (F3, H3-22S, 2024-07-01) delivered ALOS-4 (DAICHI-4), a PALSAR-3 L-band SAR Earth observation satellite.^[4]