The Small Satellite Launch Vehicle is a 34-metre, 120-tonne rocket built to put satellites of up to 500 kg into a 500 km orbit at short notice and low cost. Three solid stages do the heavy lifting and a small liquid Velocity Trimming Module fine-tunes the final orbit. After a failed first flight in 2022 it succeeded twice, completing development in 2024.
SSLV has flown three times. All three flights are here — with what went wrong on the first, and how it was fixed.
3 milestones from 2022 to 2024: 2 successes, 1 failures, 0 partial successes and 0 other milestones.
Small satellites were usually launched as passengers on bigger rockets, waiting for a slot. SSLV was designed to give them a ride of their own, assembled by a small team in days rather than months.
16 Aug 2024 · SSLV · Success
The third flight placed the EOS-08 Earth-observation satellite precisely in orbit. ISRO said the mission completed the SSLV development project and opened the way for operational launches by Indian industry and NewSpace India Limited (NSIL).
10 Feb 2023 · SSLV · Success · First SSLV success
SSLV-D2 placed EOS-07 and two passenger satellites — Janus-1 and AzaadiSAT-2 — in their planned orbit, the first time an SSLV launched satellites successfully.
Comeback from SSLV-D1.
What went wrong: SSLV released its satellites into an unstable orbit, and they re-entered.
Why: Vibration at second-stage separation upset the accelerometers; the software declared them faulty and switched to a backup mode that cut the final burn short.
What fixed it: The separation system and the sensor-failure logic were changed; SSLV-D2 placed its satellites correctly six months later.
7 Aug 2022 · SSLV · Failure
The first SSLV carried EOS-02 and AzaadiSAT, a satellite built by girl students from schools across India. All three solid stages fired, but the rocket fell short of placing the satellites in their intended orbit; they re-entered soon after.
SSLV stands for Small Satellite Launch Vehicle. It carries satellites of up to about 500 kg to low Earth orbit.
SSLV is much smaller — 120 tonnes against PSLV's 320 — and carries up to 500 kg to a 500 km orbit, while PSLV carries about 1,750 kg to sun-synchronous orbit. SSLV is all-solid apart from a small trimming module and is designed to be assembled quickly by a small team for dedicated small-satellite launches.
ISRO's chairman explained after the flight that vibration during second-stage separation disturbed the accelerometers. The flight software wrongly treated them as failed and switched to a backup mode, so the final stage did not burn long enough and the satellites ended up in an unstable orbit.
After SSLV-D3 completed development in August 2024, ISRO said future SSLV missions would be operational launches by Indian industry and NewSpace India Limited (NSIL), ISRO's commercial arm, through a technology-transfer process.
Related: All ISRO Rockets, PSLV, ISRO Missions Timeline, Next ISRO Launch.