SS-520 is a two-stage sounding rocket developed by Japan’s ISAS that was combined with a small solid third stage motor in an unsuccessful 2017 orbital launch attempt.
The sounding rocket was designed to lift up to 140 kg to a suborbital apogee of about 800 km. The rocket is rail-launched like most sounding rockets and uses spin stabilization effected by canted tail fins.
SS-520 debuted in January, 1998 from Kagoshima (as SS-520-1). ISAS launched a subsequent SS-520 (SS-520-2) from Spitsbergen, Norway in 2000. SS-520-3 is planned to fly from Norway in the future. SS-520-4 was the 2017 orbital attempt.
Sounding Rocket Orbit Try Fails
Japan’s SS-520-4, a small experimental three-stage orbital launcher based on an existing two-stage sounding rocket, failed during its inaugural attempt from Uchinoura Space Center at Kagoshima on January 14, 2017. The solid-fueled rocket zipped skyward from its rail launcher at the KS sounding rocket pad at 23:33 UTC, aiming to place Tricom 1, a 3kg Cubesat, into a 180 x 1,500 km x 31 deg orbit after a rapid ascent lasting just over four minutes.
The first stage burn appeared to be good, ending after about 31 seconds, but the second stage never ignited as planned after a 140 second coast. Reports indicated that telemetry was lost even before first stage cutoff. Second stage ignition needed to be enabled from the ground, which was impossible without an established downlink. The vehicle apparently fell into the expected first stage drop zone, indicating that the first stage propulsion phase had more or less succeeded.
SS-520-4 (SS-520 serial number 4) weighed about 2.6 tonnes at launch, which would have made it the lightest-ever orbital rocket had it succeeded. The rocket was 9.54 meters long and 0.52 meters diameter. It’s first stage HTPB solid fuel motor produced about 18 tonnes of liftoff thrust.
The launch was to be a one-off experiment, so no additional SS-520-4 orbital attempts are expected.
Also read: Hyperbola 1 (SQX 1) Data Sheet
Vehicle Configurations
| LEO Payload (metric tons) [1] 180 x 1,500km x 31 deg | Configuration | LIftoff Height (meters) | Liftoff Mass (metric tons) | ||
| SS-520 (3-stg) | ~4kg | 2stg SS-520 + stg3 | 9.65 m | 2.6 t | |
Vehicle Components
| Stg 1 | Stg 2 | Stg 3 | Payload Fairing | |
| Diameter (m) | 0.52 m | 0.52 m | – m | – m |
| Length (m) | – | – | – | – |
| Propellant Mass (tonnes) | – | – | – | – |
| Empty Mass (tonnes) | – | – | – | – |
| Total Mass (tonnes) | 1.587 t | 0.325 t | 0.078 t | ~0.00162 t |
| Engine | – | – | – | – |
| Engine Mfgr | – | – | – | – |
| Fuel | Solid HTPB | Solid HTPB | Solid HTPB | – |
| Oxidizer | – | – | – | – |
| Thrust (SL tons) | ~18 t | – | – | – |
| Thrust (Vac tons) | – | – | – | – |
| ISP (SL sec) | – | – | – | – |
| ISP (Vac sec) | – | – | – | – |
| Burn Time (sec) | 31.7 s | ~24 s | ~30s | – |
| No. Engines | 1 | 1 | 1 | – |
SS-520 Orbital Launch Log
SS-520 ORBITAL SPACE LAUNCH LOG DATE VEHICLE ID PAYLOAD MASS(t) SITE* ORBIT* ------------------------------------------------------------------------------------ 01/14/17 SS-520 SS-520-4 Tricom 1 0.003 KA KS [FTO][1] ------------------------------------------------------------------------------------ [1] Telemetry lost during Stg 1 burn. Stg 2 not enabled. Site Code: KA = Kagoshima, Japan KS = KS Sounding Rocket Launch Pad Orbit Code: EEO/M = Molynia (12-hr) Elliptical Earth Orbit FTO = Failed to Orbit FSO = Failed Suborbital GTO = Geosynchronous Transfer Orbit GTO+ = Supersynchronous or High Perigee Transfer Orbit GTO- = Subsynchronous Transfer Orbit GTOi = Inclined GTO GEO = Geosynchronous Orbit HCO = Heliocentric (solar) Orbit HTO = High Earth Transfer Orbit LEO = Low Earth Orbit LEO/S = Sun Synchronous Low Earth Orbit LEO/P = Polar Low Earth Orbit MEO = Medium Earth Orbit MTO = Medium Earth Transfer Orbit SUB = Suborbital xxx
