Vibration disturbance led to SSLV mission failure: ISRO report

India’s first Small Satellite Launch Vehicle (SSLV) carrying the Earth Observation Satellite (EOS – 02) and a co-passenger satellite AzaadiSAT lifts off from the first launchpad at Sriharikota on August 07, 2022.
| Photo Credit: Ragu R

The Indian Space Research Organisation (ISRO) on Wednesday released the failure analysis report of the Small Satellite Launch Vehicle (SSLV-D1), which failed during its maiden launch in August last year.

According to the ISRO, the cause of the anomaly was due to a vibration disturbance for a short duration on the Equipment Bay (EB) deck during the second stage separation.

“Detailed analysis of the flight events and observations ranging from countdown, lift-off, propulsion performance, stage separations and satellite injection revealed that there was a vibration disturbance for a short duration on the Equipment Bay deck during the second stage separation, that affected the Inertial Navigation System, resulting in declaring the sensors faulty by the logic in Fault Detection & Isolation software,” states the summary of the failure analysis.

The first developmental flight of the SSLV lifted off from the Satish Dhawan Space Centre on August 7, 2022 to inject EOS-02 satellite of the ISRO into a circular orbit of 356.2 km. Azaadisat, a student satellite, was part of the mission.

Corrective actions

The report further stated that though the salvage mode was initiated with the purpose of saving the mission, it could not inject the satellites into a safe orbit.

The failure analysis report has recommended a few corrective actions which include change of separation system, dynamic characterisation and design modification of structures, usage of NaVIC data, also considering Velocity Trimming Module (VTM) in loop for salvage mode among others.

“Considering the clear identification of the cause of the flight anomaly and suggested corrective actions, the next development flight [SSLV-D2] is planned to be executed complying to the recommendations, its satisfactory implementation, review and approval by the authorised committees,” the report added.

The second developmental flight of SSLV (SSLV-D2/EOS-07 Mission) is scheduled in the first quarter of 2023 and will launch a total payload mass of about 334 kg, including EOS-07 satellite and two co-passenger satellites, the ISRO said.