ISRO Launched Maiden SSLV, suffers with upper stage and dataloss issues

The SSLV-D1 rocket launched with 2 satellites and could not place in desired orbits.

SSLV-D1 liftoff (Photo: ISRO)

Chennai, August 07, 2022 The Small Satellite Launch Vehicle or SSLV carrying EOS-2 and Azaadisat satellites lifted off from the first launch pad of Satish Dhawan Space Centre in Sriharikota at 9.18am IST (03:48 UTC), after the countdown for the mission began at 2:26am. However, The Indian Space Research Organisation (ISRO) on Sunday said its SSLV-D1/EOS-02 mission suffered a data loss in its terminal phase.

"We are processing the data to conclude on the final outcome of the mission with respect to whether a stable orbit is achieved or not," said ISRO chairman S Somanath in post-flight announcement.

All the stages performed normal. Both the satellites were injected. But, the orbit achieved was less than expected, which makes it unstable. - ISRO

During the Broadcast, It is noted that the Telemetry was lost about 9 minutes into the mission. The rocket got close to orbit but may have fallen a bit short, the third and VTM stage underperformed, compared to its preliminary timeline published by ISRO.

Astronomer Dr Jonathan McDowell observed the orbital elements of the 3rd and VTM stages, did not reach the desired orbit and the stages and payload would have impacted the Pacific around 0431 UTC.

Update from ISRO: SSLV-D1 placed the satellites into 356 km x 76 km elliptical orbit instead of 356 km circular orbit. Satellites are no longer usable. The issue is reasonably identified. Failure of a logic to identify a sensor failure and go for a salvage action caused the deviation.

A committee would analyze and recommend. With the implementation of the recommendations, ISRO will come back soon with SSLV-D2.

A detailed statement by Chairman, ISRO will be uploaded soon.



The 120-tonne SSLV, which is an all-solid stage rocket measuring 34 metre in height and two metre in diameter, is capable of launching mini, micro or nanosatellites weighing 10 to 500kg mass to 500 km planar orbit. SSLV is a three-stage vehicle. All these three are solid propulsion stages.

SSLV-D1 liftoff (Photo: ISRO)

The key features of SSLV include low cost, low turnaround time, flexibility in accommodating multiple satellites, launch-on-demand feasibility, minimal launch infrastructure requirements. The rocket can be made within one week because of many innovative features introduced. These include modular systems, simplified pyro circuit and modular feature for separation system, multi-satellite adapter deck, miniature low-cost avionics with commercial off-the-shelf components, on-board computer with rapidly reconfigurable check-out system with the minimum ground interface. Some of the new systems introduced in the launch vehicle include SS1 motor, which is the third largest solid booster of ISRO, SS3 motor, which is a new composite upper stage solid motor, and liquid propulsion-based terminal stage for precise injection of satellites.


VTM and Payload Adapter mounted with EOS-02 and AzaadiSAT (Photo: ISRO)

Two satellites The 145kg EOS-2 is an experimental imaging satellite with a short turn-around time. Azaadisat is an 8U Cubesat weighing around 8kg. It carries 75 different payloads each weighing around 50gram and conducting femto-experiments. The payloads were built by girl students from rural regions across the country. The payloads include a UHF-VHF transponder working in ham radio frequency to enable voice and data transmission for amateur radio operators, a solid state PIN diode-based radiation counter to measure the ionising radiation in its orbit, a long-range transponder and a selfie camera.

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