SS-520 – Space Launch Report

SS-520 – Space Launch Report

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

SS-520 – Space Launch Report

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

(metric tons)
[1] 180 x 1,500km x 31 deg
(metric tons)
SS-520 (3-stg)~4kg 2stg SS-520 + stg39.65 m2.6 t

Vehicle Components

 Stg 1Stg 2Stg 3Payload
Diameter (m)0.52 m0.52 m–  m– m
Length (m)
Propellant Mass (tonnes)
Empty Mass (tonnes)
Total Mass (tonnes)1.587 t0.325 t0.078 t~0.00162 t
Engine Mfgr
(SL tons)
~18 t
(Vac tons)
ISP (SL sec)
ISP (Vac sec)
Burn Time (sec)31.7 s~24 s~30s
No. Engines111

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
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