Small Satellite Launch Vehicle
The Small Satellite Launch Vehicle (SSLV) is a small-lift launch vehicle developed by the Indian Space Research Organisation (ISRO) to provide low-cost, on-demand access to orbit for small satellites.[1] It is designed to deliver payloads of up to 500 kg to a 500 km low Earth orbit (LEO), targeting mini, micro, and nano satellites in the mass range of 10–500 kg.[1] The SSLV is a three-stage vehicle using solid propulsion for the first three stages and a liquid-fueled velocity addition module, enabling dedicated launches with a turnaround time of 72 hours and a cost of approximately US$4 million per launch. Launched from the Satish Dhawan Space Centre, the SSLV addresses the growing demand for responsive space access amid the proliferation of small satellite constellations for communications, Earth observation, and research.[2] Its development supports India's commercialization efforts through NewSpace India Limited (NSIL), with a successful third developmental flight (SSLV-D3) in August 2024 deploying the EOS-08 satellite.[3] In September 2025, ISRO signed a technology transfer agreement with Hindustan Aeronautics Limited (HAL) to enable private production of the SSLV, enhancing scalability and market reach.[4] The SSLV exemplifies global trends in small launch vehicles, which in 2024 saw small satellites comprise 97% of the 2,873 spacecraft launched worldwide across 259 missions, with 77% of launches incorporating smallsats and 6% using dedicated small launchers.[5] The broader small launch vehicle market, valued at US$1.55 billion in 2023, is projected to reach US$4.29 billion by 2032 at a CAGR of 11.12% (2024–2032).[6] Comparable systems include Rocket Lab's Electron, capable of 300 kg to LEO.[7]Development History
Program Initiation and Objectives
The Small Satellite Launch Vehicle (SSLV) program originated from a proposal in December 2015 by the National Institute of Advanced Studies, which advocated for the development of a dedicated small-lift launch vehicle to address the burgeoning demand for nanosatellite and microsatellite launches in the global market.[8] This initiative was driven by the rapid expansion of the small satellite sector, with satellite launches increasing significantly from 2015 onward, as documented in industry analyses showing a surge in deployments from under 100 annually in 2015 to over 2,000 by 2023.[5] The Indian Space Research Organisation (ISRO) formally began SSLV development in late 2017 to provide a cost-effective alternative to rideshare opportunities on larger vehicles like the Polar Satellite Launch Vehicle (PSLV), which often imposed scheduling constraints and limited dedicated access for small payloads.[9] The primary objectives of the SSLV program centered on enabling low-cost, on-demand launches for payloads up to 500 kg into a 500 km sun-synchronous orbit (SSO), with a targeted turnaround time of under 72 hours from assembly to launch and reliance on minimal ground infrastructure.[1][10] Unlike the PSLV, which requires approximately 70 days for integration and a large team, the SSLV was designed for rapid production and operation by a small crew of six, facilitating frequent missions to capture a share of the commercial small satellite market.[8] The Indian government approved the SSLV development project, sanctioning a total funding of ₹169 crore to cover vehicle qualification, systems development, and three demonstration flights, with an initial target for the first flight in 2019 that was subsequently delayed to 2022 due to technical refinements.[11] This investment underscored ISRO's strategic focus on enhancing India's competitiveness in the evolving small satellite ecosystem, prioritizing accessibility for academic, startup, and international customers seeking dedicated launches without the complexities of multi-payload configurations.[1]Design Evolution and Challenges
The development of the Small Satellite Launch Vehicle (SSLV) began with a proposal in 2015 to create a cost-effective launcher for small payloads up to 500 kg into low Earth orbit, initially conceptualizing the use of solid boosters derived from the Polar Satellite Launch Vehicle (PSLV) to leverage existing technology.[12][13] By late 2018, the Vikram Sarabhai Space Centre initiated detailed design work, evolving the configuration to a fully integrated four-stage vehicle, comprising three solid propulsion stages and a liquid-based Velocity Trimming Module (VTM) as the terminal stage, emphasizing simplicity, reduced infrastructure needs, and rapid turnaround times of 72 hours.[8][1] A primary technical challenge was achieving precise orbit insertion using predominantly solid stages, which lack the throttleability of liquids; this was addressed through the VTM, employing 16 attitude control thrusters fueled by monomethylhydrazine and nitrogen tetroxide to provide three-axis control and velocity corrections for accurate payload deployment.[8][14] Another obstacle involved managing structural vibrations during ascent, particularly in the upper stages, which could affect sensor performance and stability; early ground tests revealed nozzle issues in the first stage, necessitating redesigns and additional qualification firings.[15][16] Avionics miniaturization posed further difficulties, requiring compact, low-power systems to fit the vehicle's reduced scale while maintaining reliability; this was mitigated by integrating commercial off-the-shelf (COTS) components for navigation and control, including NavIC-enabled inertial systems with MEMS sensors.[17][18] Key milestones marked steady progress amid setbacks: hardware prototype assembly for upper stages was completed by mid-2019, enabling initial integration trials, while the first static test of the SS1 (first) stage occurred in March 2021 but failed due to a nozzle malfunction at 95 seconds, prompting a redesign and successful retest in March 2022.[8][15] Following the SSLV-D1 developmental flight failure in August 2022—attributed to vibration-induced errors in the VTM's inertial measurement unit—failure analysis led to enhancements in vibration isolation and sensor redundancy for subsequent missions, solidifying the liquid propulsion role in stage 4 for improved precision.[16][19] To optimize costs and development speed, the SSLV adopted a uniform 2-meter stage diameter—significantly narrower than the PSLV's 2.8-meter core—allowing for lighter structures and compatibility with existing solid motor casings derived from prior programs, while extensive use of COTS electronics reduced custom fabrication needs and overall program expenses to approximately $21 million.[1][20][12]Qualification Testing
Qualification testing for the Small Satellite Launch Vehicle (SSLV) encompassed a series of ground-based evaluations to verify structural integrity, propulsion performance, and subsystem compatibility prior to developmental flights. These tests were conducted primarily at the Satish Dhawan Space Centre and other ISRO facilities, focusing on simulating launch environments to ensure reliability for small satellite deployments. Ground tests began with structural assessments, including vibration and acoustic evaluations on key subsystems to replicate dynamic loads during ascent. The Acoustic Test Facility completed tests on two SSLV subsystems, confirming their resilience to high noise levels equivalent to launch conditions. Vibration testing addressed potential disturbances, with early characterizations identifying issues like oscillations in the first stage during initial trials.[21][8][22] Propulsion qualification involved hot firings of individual stages. The Solid Booster Stage (SS1) underwent its first static test in March 2021, which failed at 95 seconds due to nozzle malfunction after oscillations began at 60 seconds, prompting minor adjustments. A successful second hot firing of SS1 occurred in March 2022, validating full-duration performance. Stages SS2 and SS3 completed their ground hot tests by early 2022, demonstrating nominal thrust and burn characteristics without anomalies. Additionally, the SSLV Payload Fairing (SPLF) passed functional qualification testing in August 2021, ensuring separation reliability under aerodynamic loads.[8][23][24] Integrated vehicle testing followed component qualifications, involving full-stack assembly and interface verifications in early 2022. This included checks for electrical, mechanical, and propulsion interconnections across the three solid stages and the liquid-based Velocity Trimming Module (VTM). Environmental simulations, such as thermal-vacuum chamber tests on avionics and the VTM, confirmed operational integrity in space-like conditions of extreme temperatures and vacuum. These efforts cleared the vehicle for its first developmental flight (SSLV-D1) in August 2022.[15][24] The SSLV-D1 flight revealed an anomaly where a short-duration vibration disturbance during second-to-third stage separation impacted the Equipment Bay, leading to a faulty inertial navigation sensor reading in the VTM and preventing its ignition. Post-flight analysis identified the root cause as dynamic interactions at separation, resulting in no velocity increment from the VTM and an elliptical orbit for the payloads. ISRO implemented corrective measures, including a redesigned separation system, enhanced dynamic characterization of stage interfaces, and modified logic in the VTM for sensor failure detection and salvage mode activation. These changes were ground-verified and demonstrated successfully in the second developmental flight (SSLV-D2) in February 2023.[22][25][26] The third and final developmental flight, SSLV-D3/EOS-08, launched successfully on August 16, 2024, from the Satish Dhawan Space Centre, placing the EOS-08 Earth observation satellite into a 475 km orbit. This mission validated all vehicle systems, including the VTM performance, and marked the completion of the SSLV development project, enabling transition to operational and commercial launches.[27] Overall, SSLV qualification adhered to rigorous standards for component and system reliability, with ground tests achieving nominal performance across propulsion and structural elements, paving the way for operational certification through subsequent flights.[28]Technical Design
Vehicle Configuration and Stages
The Small Satellite Launch Vehicle (SSLV), developed by the Indian Space Research Organisation (ISRO), is configured as a four-stage launch system comprising three solid-propellant stages and a liquid-propellant terminal module, designed to provide dedicated and cost-effective access to space for small satellites.[1] The vehicle measures 34 meters in height, has a principal diameter of 2 meters, and a lift-off mass of approximately 120 tonnes, enabling rapid integration and minimal ground infrastructure requirements to support launch-on-demand operations.[29] This architecture aligns with ISRO's objectives for low-turnaround-time missions targeting mini, micro, and nano satellites in low Earth orbits.[1] The first stage, designated SS1, is a solid-propellant motor utilizing hydroxy-terminated polybutadiene (HTPB) fuel, with a length of 22.5 meters and a diameter of 2 meters, loaded with 87 tonnes of propellant to generate the initial thrust required for liftoff and initial ascent through the dense atmosphere.[29] Following SS1 burnout and separation, the second stage (SS2) ignites, also HTPB-based solid propellant, measuring 3.2 meters in length and 2 meters in diameter, with 7.7 tonnes of propellant to provide mid-ascent acceleration and sustain velocity buildup.[29] The third stage (SS3), similarly solid-fueled with HTPB, is shorter at 2.8 meters long and 1.7 meters in diameter, carrying 4.5 tonnes of propellant to propel the vehicle into the upper atmosphere and prepare for final orbit insertion.[29] The terminal stage, known as the Velocity Trimming Module (VTM), employs a liquid bi-propellant system using monomethylhydrazine (MMH) and mixed oxides of nitrogen (MON-3), with a length of 0.85 meters and a diameter of 2 meters, containing 0.05 tonnes of propellant for precise velocity adjustments and attitude control during orbit insertion.[30] The VTM incorporates multiple attitude control thrusters to enable accurate payload deployment, ensuring the vehicle can achieve the targeted orbital parameters without excessive deviation.[31] The design was validated through the successful SSLV-D3 mission in August 2024, with technology transfer for commercialization signed in September 2025.[32][33]| Stage | Propulsion Type | Length (m) | Diameter (m) | Propellant Mass (tonnes) | Primary Role |
|---|---|---|---|---|---|
| SS1 | Solid (HTPB) | 22.5 | 2 | 87 | Liftoff and initial ascent |
| SS2 | Solid (HTPB) | 3.2 | 2 | 7.7 | Mid-ascent acceleration |
| SS3 | Solid (HTPB) | 2.8 | 1.7 | 4.5 | Upper atmosphere push |
| VTM | Liquid (MMH/MON-3) | 0.85 | 2 | 0.05 | Precise orbit insertion and velocity trimming |
Propulsion Systems
The propulsion systems of the Small Satellite Launch Vehicle (SSLV) are engineered to deliver a total delta-v of approximately 9.5 km/s, enabling precise insertion of small satellites into low Earth orbits. The vehicle employs a combination of solid and liquid propulsion across its four stages, with the first three stages relying on high-thrust solid motors for primary ascent and the fourth stage using liquid thrusters for velocity trimming and orbit circularization. This hybrid approach balances high energy density from solids with the controllability of liquids, optimizing performance for payloads up to 500 kg in 500 km orbits. The first stage, designated SS1, utilizes a single solid rocket motor fueled by HTPB-based composite propellant, generating a maximum vacuum thrust of 2496 kN during an approximately 115-second burn.[31][30] This stage provides the initial boost, propelling the 120-tonne vehicle off the launch pad while the 2-meter diameter motor casing integrates seamlessly with the vehicle's configuration. The second stage, SS2, features a single solid motor also using HTPB propellant, producing a maximum vacuum thrust of 234.2 kN over approximately 116 seconds, with integrated nozzle vectoring to enable thrust vector control for trajectory adjustments during ascent.[31][30] The third stage, SS3, is powered by a single solid motor delivering a maximum vacuum thrust of 160 kN for approximately 108 seconds, incorporating a flexible nozzle mechanism for steering and stability in the upper atmosphere.[31][30] The fourth stage (VTM) employs a liquid bi-propellant system with 16 restartable thrusters, each rated at 50 N, to achieve fine velocity corrections of up to ±100 m/s, ensuring accurate payload deployment.[34] These systems, developed by ISRO's Liquid Propulsion Systems Centre and Solid Propulsion groups, emphasize lightweight materials and vectored thrust for improved vehicle responsiveness.[34]Avionics and Guidance
The avionics and guidance systems of the Small Satellite Launch Vehicle (SSLV) are designed for low-cost, high-reliability operation, emphasizing miniaturization and integration of commercial off-the-shelf (COTS) components to support rapid production and on-demand launches. These systems enable precise navigation, attitude control, and telemetry throughout the ascent phase, ensuring the vehicle's ability to deliver small satellites to low Earth orbits. Navigation in the SSLV relies on a low-cost Inertial Navigation System (INS) integrated with India's NavIC (Navigation with Indian Constellation) for real-time position and velocity determination. The INS, designated as the MEMS Inertial Navigation System (MINS-6S), incorporates six micro-electro-mechanical systems (MEMS) gyros to measure angular rates and six MEMS accelerometers to capture linear accelerations, providing aided navigation across the entire flight regime from liftoff to orbit insertion. This MEMS-based approach reduces size, weight, and power consumption compared to traditional ring laser gyro systems, while maintaining the accuracy needed for sub-kilometer orbit insertion. Guidance and control are managed by a digital control system that implements closed-loop algorithms for three-axis stabilization during powered flight and coast phases. In the solid-propellant stages (SS1 through SS3), attitude adjustments are achieved via thrust vector control (TVC) using gimbaled nozzles, allowing ±3° deflection for pitch and yaw steering. The fourth stage, the liquid propulsion-based velocity trimming module (VTM), employs reaction control systems (RCS) using its bipropellant thrusters for fine three-axis control and orbit maneuvers. The avionics stack features redundant architecture to enhance fault tolerance, with flight computers processing sensor data, executing guidance commands, and handling autonomous event sequencing. Telemetry transmission occurs via S-band links, enabling real-time health monitoring and mission data downlink during flight. Key operational features include autonomous stage separation triggered by pyrotechnic devices and non-explosive actuators, ensuring reliable transitions between stages without ground intervention. Software for the avionics and guidance is rigorously validated through hardware-in-the-loop (HIL) simulations, which replicate flight dynamics and sensor inputs to verify performance under nominal and off-nominal conditions. Overall miniaturization confines the avionics package within the vehicle's 2-meter diameter fairing, powered by lithium-ion batteries to meet the ~5 kWh energy demands for the mission duration.Launch Infrastructure
Satish Dhawan Space Centre Facilities
The Satish Dhawan Space Centre (SDSC)-SHAR in Sriharikota, Andhra Pradesh, provides the core launch infrastructure for the Small Satellite Launch Vehicle (SSLV), optimized for its compact design and rapid deployment needs. Launch Pad 3 (LP-3), the first dedicated pad at SDSC-SHAR for small-lift vehicles like the SSLV, features an umbilical tower for supplying electrical power, data, and gases during final checks, a mobile service tower for technician access and payload mating, and a rail system that supports horizontal vehicle integration to minimize vertical infrastructure demands.[35] Assembly and integration of the SSLV occur horizontally on a rail transporter within dedicated buildings, allowing the fully stacked vehicle to be rolled out to LP-3 in about 24 hours; the payload fairing is then integrated at pad level to streamline operations and reduce preparation time compared to larger vehicles.[1] Key support buildings include the Solid Motor Preparation Facility, established in 2018, which handles casting, curing, and non-destructive testing of solid propellant segments for the SSLV's three solid stages. The liquid stage fueling station, equipped with systems for handling hypergolic liquid propellants, supports safe loading of the fourth stage's velocity trimming module.[36] Environmental adaptations at LP-3 encompass a sound suppression system using water deluge to dampen acoustic levels from solid stage ignition, which can exceed 150 dB, and multiple lightning protection towers to shield against frequent coastal thunderstorms. Overall, these facilities are configured for multiple SSLV launches annually, leveraging the vehicle's minimal infrastructure footprint for swift turnaround between missions.[37]Ground Operations and Support
The ground operations for the Small Satellite Launch Vehicle (SSLV) emphasize efficiency and minimal infrastructure, with the launch campaign designed for a rapid turnaround of approximately 72 hours from vehicle assembly to liftoff, in contrast to the 70 days typically required for the PSLV. This process begins with the mating of the vehicle's solid propulsion stages and liquid velocity trimming module in assembly halls at the Satish Dhawan Space Centre (SDSC), followed by payload fairing encapsulation. The short timeline supports launch-on-demand feasibility, allowing ISRO to accommodate multiple small satellites with flexibility in orbit insertion parameters. Hazardous operations, such as loading propellants into the liquid stage, are conducted during the final preparation phase, typically on D-2, under strict procedural controls to mitigate risks. Payload integration logistics are handled collaboratively, with customer representatives performing the final mating of satellites to the vehicle adapter under ISRO supervision in dedicated cleanrooms at SDSC to prevent contamination and ensure mechanical and electrical compatibility. This customer-involved approach streamlines the workflow while maintaining quality standards, enabling payloads up to 500 kg to be accommodated for low Earth orbit missions. Real-time mission support is provided from the Mission Control Centre (MCC) at SDSC, which integrates telemetry, tracking, and command systems for vehicle monitoring throughout the flight. Range safety operations utilize a network of downrange tracking stations, including radars and optical sensors extending over 2,000 km along the trajectory path, connected via redundant satellite links to enable precise trajectory assessment and rapid response. The SSLV's high degree of automation in its avionics and launch sequence allows operations to be managed by a compact team of about six engineers, substantially reducing manual interventions compared to the larger crews needed for vehicles like the PSLV. Safety protocols are integral to SSLV ground operations, incorporating a flight termination system that can be activated by telecommand from the Range Safety Officer console to destruct the vehicle if it deviates from the nominal path. Launches proceed only under favorable weather conditions, including low wind speeds and clear visibility, to safeguard personnel and assets. Following liftoff, ISRO performs post-launch debris analysis through its space situational awareness program, tracking any orbital fragments to evaluate re-entry risks and environmental impact.Launch Chronology
Developmental Flights
The developmental phase of the Small Satellite Launch Vehicle (SSLV) consisted of three qualification flights designated SSLV-D1, SSLV-D2, and SSLV-D3, conducted by the Indian Space Research Organisation (ISRO) to validate the vehicle's design, performance, and reliability for small satellite deployment.[38] These missions focused on achieving precise orbital insertion in low Earth orbits, with each flight building on prior tests to refine stage separation, propulsion, and guidance systems. The maiden flight, SSLV-D1, lifted off on August 7, 2022, at 09:18 IST from the First Launch Pad at Satish Dhawan Space Centre (SDSC) SHAR, Sriharikota, carrying the primary payload EOS-02, an Earth observation satellite weighing 111.2 kg, and the co-passenger AzaadiSAT-2, an 8 kg student-built CubeSat.[14] The mission encountered a partial failure when an anomaly during the second stage separation generated excessive vibration in the equipment bay, leading to a faulty sensor reading in the fourth stage's Velocity Trimming Module (VTM), a liquid propulsion system for fine orbit adjustments.[25] This prevented proper ignition and salvage mode activation, resulting in the payloads being injected into an elliptical orbit of 356 km apogee and 76 km perigee at 37.2° inclination, instead of the targeted 356 km circular orbit; the low perigee caused the satellites to decay and become unusable shortly after deployment.[22] Post-flight analysis confirmed that the first three solid-propellant stages performed nominally, isolating the issue to the VTM's control logic. Incorporating lessons from SSLV-D1, ISRO redesigned the fourth stage VTM by enhancing sensor failure detection logic, introducing robust salvage protocols, and mitigating vibration propagation from stage separations through structural reinforcements.[25] The second developmental flight, SSLV-D2, launched successfully on February 10, 2023, at 09:18 IST from the same SDSC facility, deploying EOS-07, a 156.3 kg Earth observation satellite, along with two smaller payloads: Janus-1 (10.4 kg, developed by Antaris of the United States) and AzaadiSAT-2 (8 kg, a student satellite).[29] All stages operated nominally, achieving precise injection into a 450 km circular Sun-synchronous orbit (SSO) at 37.2° inclination, with orbit accuracy within ±5 km in altitude and minimal inclination deviation, demonstrating improved repeatability and control.[39] This success validated the redesigned systems and marked the vehicle's transition toward operational readiness. The final developmental flight, SSLV-D3, occurred on August 16, 2024, at 09:17 IST from SDSC SHAR, carrying the primary payload EOS-08, a 175.5 kg experimental Earth observation satellite equipped with electro-optical infrared and multispectral cameras, and the secondary SR-0 DEMOSAT, a 0.56 kg technology demonstrator.[27] The mission achieved full success, with the vehicle injecting EOS-08 into a precise 475 km circular SSO at 37.4° inclination after a 16-minute ascent, confirming the SSLV's design maturity and repeatability across multiple flights.[30] Overall, the developmental flights highlighted the SSLV's low-cost, quick-turnaround capabilities while addressing early challenges like stage 4 propulsion reliability, paving the way for commercial operations with enhanced confidence in mission outcomes.[39]Operational and Commercial Missions
The Small Satellite Launch Vehicle (SSLV) transitioned to operational status following the successful SSLV-D3 mission in 2024, which carried the EOS-08 microsatellite as a semi-operational payload to demonstrate end-to-end performance with a real satellite.[32] This flight marked the completion of development, paving the way for commercial applications by validating the vehicle's ability to place payloads into sun-synchronous orbits (SSO). Planned operational missions will emphasize dedicated rideshare opportunities for small satellites, with configurations supporting up to four nanosats in multi-payload stacks to optimize capacity.[30] The first fully operational mission is scheduled no earlier than (NET) late 2025, under a commercial agreement with BlackSky Global to deploy satellites 5 and 6—each approximately 50 kg—into a 500 km SSO.[40] This launch represents NSIL's inaugural international customer contract for the SSLV, highlighting its role in providing cost-effective access to orbit for commercial Earth observation payloads. Pricing for such missions stands at $5-7 million per launch in 2025 rates, enabling competitive services for payloads under 500 kg.[41] In June 2025, HAL was selected for the technology transfer, with the formal agreement signed on September 10, 2025, shifting responsibility for SSLV production and launches to Hindustan Aeronautics Limited (HAL).[33] The technology transfer is expected to be completed within 24 months, with HAL's first independently produced SSLV ready by 2027.[42] This positions HAL to conduct 6-8 missions annually and handle marketing via NSIL. This handover includes full autonomy in mission preparation, with HAL demonstrating independent operations during 2025 ground campaigns. No anomalies have been reported in post-D3 activities, underscoring the vehicle's reliability for sustained commercial operations.[4]Performance Specifications
Payload Capacity and Orbits
The Small Satellite Launch Vehicle (SSLV), developed by the Indian Space Research Organisation (ISRO), is optimized for delivering small payloads into low Earth orbits, with baseline performance enabling 500 kg to a 500 km low Earth orbit (LEO) and 300 kg to a 500 km sun-synchronous orbit (SSO).[1] This capacity supports mini, micro, and nano satellites in the 10-500 kg class, catering to commercial, scientific, and educational missions requiring dedicated launches.[1] As altitude increases, the achievable payload mass decreases due to the vehicle's fixed total impulse from its three solid-propellant stages and liquid-based Velocity Trimming Module (VTM).| Orbit Type | Altitude | Maximum Payload (kg) |
|---|---|---|
| LEO (planar) | 500 km | 500 |
| SSO | 500 km | 300 |
| SSO | 700 km | ~250 |
| LEO | 1500 km | ~100 |
Reliability and Success Metrics
The Small Satellite Launch Vehicle (SSLV) has demonstrated a developmental success rate of 67% across its three flights conducted by November 2025, with two fully successful missions out of three. As of November 2025, the SSLV has completed its developmental phase with three flights, paving the way for commercial operations via technology transfer. The inaugural flight, SSLV-D1 in August 2022, resulted in a partial failure due to vibration disturbances during second stage separation that affected the inertial navigation system, preventing precise orbital insertion despite the vehicle reaching space. Subsequent redesigns addressed vibration-induced issues through enhanced structural damping and sensor recalibration, leading to 100% success in the following developmental flights: SSLV-D2 in February 2023 and SSLV-D3 in August 2024. These later missions successfully deployed payloads into intended low Earth orbits: SSLV-D2 deployed EOS-07 (156.3 kg), Janus-1, and AzaadiSAT-2 totaling approximately 334 kg into a 450 km orbit at 37.2° inclination; SSLV-D3 deployed EOS-08 (175.5 kg) and SR-0 (0.56 kg) into a 500 km SSO at 98.5° inclination.[38][44][45][29][30] Key performance metrics highlight the SSLV's operational reliability in critical phases post-redesign. Orbital insertion accuracy for SSLV-D2 and D3 achieved 100%, with payloads placed within specified orbits. Stage separation reliability across all three flights stood at 100% for the first three stages, with no anomalies reported after the D1-specific issue was rectified. Additionally, no range safety activations or self-destruct interventions were required in any mission, underscoring robust flight termination systems and trajectory control. Overall, these metrics reflect ISRO's focus on high-reliability solid propulsion, contributing to the vehicle's minimal ground infrastructure needs.[46] Following the SSLV-D1 failure, ISRO implemented targeted improvements, validated in ground tests, eliminating resonance issues and improving thrust vector control stability, enabling the flawless performance in subsequent flights. With technology transfer to Hindustan Aeronautics Limited (HAL) completed in September 2025, production scaling is underway for commercial missions.[47][33][4] Compared to peer small-lift vehicles, the SSLV offers competitive advantages in cost and turnaround time, though its success rate lags behind more mature systems. The table below summarizes key metrics:| Vehicle | Success Rate | Payload to 500 km LEO | Cost per Launch | Turnaround Time |
|---|---|---|---|---|
| SSLV (ISRO) | 67% | 500 kg | ~$4 million | 72 hours |
| Electron (Rocket Lab) | 94% | 300 kg | $7.5 million | ~1 month |
| Vega-C (Arianespace) | 80% | 2,200 kg | ~$45 million | Several months |