Another chance for SS-520-4

JAXA decided to give another chance to their latest sounding rocket, SS-520-4. After disaster of the rocket during flight performed on January 14, 2017 from Kagoshima Space Center, Japanese Space Agency still sees potential in smallest launch vehicle ever created.

Next flight of SS-520-4 should be performed before end of this year and will cost JAXA approximately from  $2.64 and $4.4 million according to a Nikkei report. Again rocket will be launched from Kagoshima Space Center. Chance that this time rocket will reach orbit and deploy satellite increased with announcing by JAXA, that team of engineers discovered main reason why SS-520-4 failed on 14 January

Main reason why long for 9.5 m three stage rocket was destroyed was not easy to detect. First of all rocket failed to deliver telemetry data before it exploded, so engineers in fact didn’t know nothing about flight parameters in the moment when exactly problem appeared. Limited data were provided only by tracking station and showed, that rocket reached 190 km of altitude – this fact confirmed that first stage performed lasting 31.7 s burn correctly. It was not quite sure why second stage did not ignite, but in understanding reasons helped simplicity of the construction of SS-520-4. Its onboard computer could start propulsion of the second stage only after receiving confirmation of reaching certain altitude. Because telemetry was interrupted at T+20.4 s it simply did not ignite second stage due the lack of receiving appropriate data from sensor. Second stage and third stage with Tricom-1 satellite fall into Pacific. Engineers finally discovered why rocket stopped to provide telemetry – it was caused by tearing one of the wires placed inside second stage. It was directly connected to one of the sensors and lead with other wires placed on aluminium structure of the stage (inside special cutout covered with aluminium sheath). Experiment performed by engineers showed, that vibrations during flight could cause tearing isolation of the wire placed directly on aluminium profile even if it was secured with fiberglass tape. This tear cause short circuit between wire and grounded structure and generated current of over 40 A. This caused malfunction of electrical system and interrupted transmitting telemetry. JAXA announced that construction of this part will be changed to remove this problem in future.