Small Satellite Launch Vehicle
FunctionSmall-lift launch vehicle
ManufacturerNSIL, ISRO[1]
Country of originIndia
Cost per launch35 crore (US$4.4 million) (expected)[2][3][4][5]
Height34 m (112 ft)
Diameter2 m (6 ft 7 in)
Mass120 t (120 long tons; 130 short tons)
Payload to low Earth orbit
Altitude500 km (310 mi)[7]
Orbital inclination45.0°
Mass500 kg (1,100 lb)
Payload to Sun-synchronous orbit
Altitude500 km (310 mi)[7]
Mass300 kg (660 lb)
Associated rockets
Launch history
Launch sitesSatish Dhawan Space Centre Kulasekarapattinam Spaceport
Total launches2
First flight03:48 UTC, 7 August 2022.[8]
Last flight10 February 2023, EOS-07
First stage – SS1
Diameter2 m
Propellant mass87,000 kg (192,000 lb)[9]
Powered byS85
Maximum thrust2,496 kN (vac)[10]
Burn time94.3 s[10]
PropellantSolid (HTPB based)
Second stage – SS2
Diameter2 m
Propellant mass7,700 kg (17,000 lb)[9]
Powered byS7
Maximum thrust234.2 kN (vac)[10]
Burn time113.1 s[10]
PropellantSolid (HTPB based)
Third stage – SS3
Diameter1.7 m
Propellant mass4,500 kg (9,900 lb)[9]
Powered byS4
Maximum thrust160 kN (vac)[10]
Burn time106.9 s[10]
PropellantSolid (HTPB based)
Fourth stage – Velocity Trimming Module (VTM)
Diameter2 m
Propellant mass50 kg (110 lb)[9]
Powered by16×50N bipropellant thrusters[10]
PropellantMMH+MON3 Liquid

The Small Satellite Launch Vehicle (SSLV) is a small-lift launch vehicle developed by ISRO with payload capacity to deliver 500 kg (1,100 lb) to low Earth orbit (500 km (310 mi)) or 300 kg (660 lb) to Sun-synchronous orbit (500 km (310 mi))[7] for launching small satellites, with the capability to support multiple orbital drop-offs.[11][12][13] SSLV is made keeping low cost, low turnaround time in mind with launch-on-demand flexibility under minimal infrastructure requirements.[14]

The maiden flight SSLV-D1 was conducted on 7 August 2022,[8][15] from the First Launch Pad, but failed to orbit.[16] A second flight SSLV D2 was conducted on 10 February 2023 that successfully delivered payloads to orbit.[17]

In the future, a dedicated launch site in Kulasekharapatnam, Tamil Nadu will handle SSLV launches to Sun-synchronous orbit.[18][19][20][21] After entering the operational phase, the vehicle's production and launch operations will be done by a consortium of Indian firms along with NewSpace India Limited (NSIL).[22][23][24]

Vehicle description

EOS 02 spacecraft and VTM upper stage integrated in a cleanroom facility.

The SSLV was developed with the aim of launching small satellites commercially at drastically reduced price and higher launch rate compared to Polar Satellite Launch Vehicle (PSLV). The development cost of SSLV is 169.07 crore (equivalent to 190 crore or US$24 million in 2023)[16][2] and the manufacturing cost is expected to be 30 crore (US$3.8 million) to 35 crore (US$4.4 million).[3][23][4]

The projected high launch rate relies on largely autonomous launch operation and on overall simple logistics. To compare, a PSLV launch involves 600 officials while SSLV launch operations would be managed by a small team of about six people. The launch readiness period of the SSLV is expected to be less than a week instead of months.[25][26] The launch vehicle can be assembled both vertically like the existing PSLV and Geosynchronous Satellite Launch Vehicle (GSLV) and horizontally like the retired Satellite Launch Vehicle (SLV) and Augmented Satellite Launch Vehicle (ASLV).[27]

The first three stages of the vehicle use HTPB based solid propellant, with a fourth terminal stage being a Velocity-Trimming Module (VTM) with eight 50 N thrusters for reaction control and eight 50 N axial thrusters for changing velocity.[10] With these VTM can add delta-v of up to 172 m/s.[28]

The first stage (SS1) and third stage (SS3) of SSLV are newly developed while second stage (SS2) is derived from third stage (HPS3) of PSLV.[29][30][31]

Vehicle characteristics:[32][33]

Payloads capabilities[7][34]

SSLV Launch Complex

Main article: Kulasekharapatnam Spaceport

The early developmental flights and those to inclined orbits will launch from Sriharikota,[19] at first using existing launch pads and later from dedicated facility called SSLV Launch Complex (SLC) in Kulasekharapatnam.[35][18] Tenders related to manufacturing, installation, assembly, inspection, testing and Self Propelled launching Unit (SPU) were released in October 2019.[36][37][38]

This new spaceport, under development, near Kulasekharapatnam in Tamil Nadu will handle SSLV launches to Sun-synchronous orbit when complete.[20][39][40]



In 2015, a National Institute of Advanced Studies report by Rajaram Nagappa proposed development path of a 'Small Satellite launch Vehicle-1' to launch strategic payloads.[41] In National Space Science Symposium 2016,[42] then Director of Liquid Propulsion Systems Centre, S. Somanath also acknowledged a need for identifying a cost effective launch vehicle configuration with 500 kg payload capacity to LEO[43] and by November 2017, development of such launch vehicle was underway.[44]

By December 2018, the Vikram Sarabhai Space Centre (VSSC) completed the design for the vehicle.[45]

In December 2020, all booster segments for SSLV first stage (SS1) static test (ST01) were received and assembly was done in Second Vehicle Assembly Building (SVAB).[46]

The first static fire test (ST01) of the SS1 first-stage booster conducted on 18 March 2021 was unsuccessful.[47][48] About 60 seconds into the test, oscillations were observed and after 95 seconds, the nozzle of SS1 stage disintegrated. The nominal duration of test was 110 seconds.[49] To qualify for flight, SSLV's solid first stage SS1 has to perform two consecutive nominal static fire tests.[49]

The SSLV Payload Fairing (SPLF) functional qualification test was completed in August 2021.[50]

The second static fire test of SSLV first stage SS1 was conducted on 14 March 2022 at SDSC-SHAR and met the required test objectives.[51][52]

Operational history


The first developmental flight of the SSLV occurred on 7 August 2022. The flight mission was named SSLV-D1. The SSLV-D1 flight failed to achieve its mission objectives.

The rocket had a three stage configuration with a fourth Velocity Trimming Module (VTM). In its D1 configuration, the rocket was 34m tall with a diameter of 2m and a lift-off mass of 120t.[53]

The rocket carried EOS 02, an Earth observation satellite that weighed 135 kg and AzaadiSAT, a CubeSat payload that weighed 8 kg, developed by Indian students to promote inclusivity in STEM education. The SSLV-D1 was supposed to place the two satellite payloads in a circular orbit of altitude 356.2 km with 37.2° inclination.

The official explanation by the ISRO for the mission failure was software malfunction.[54][55][56] According to the ISRO, the mission software detected an accelerometer anomaly during the second stage separation. This caused the rocket navigation to switch from a closed loop guidance to an open loop guidance.[57] Even though, this switch in guidance mode was part of the redundancy built into the rocket's navigation, it could not salvage the mission.

During the open loop guidance mode, the final VTM stage only managed to fire for 0.1s instead of the intended 20s.[58] This led to the two satellites as well as the VTM stage of the rocket being injected into an unstable elliptical transatmospheric orbit of 360.56×75.66 km with an inclination of 36.56°.[56]

The SSLV-D1's final VTM stage had 16 hydrazine (MMH+MON3) fueled thrusters. Eight of those were to provide altitude control and the remaining eight for controlling the orbital velocity.[59] The VTM stage also provided pitch, yaw and roll control during the orbital insertion maneuvers.[60] The three main stages of the SSLV-D1 functioned normally. But, that was not enough to impart adequate impulse for the two satellite payloads to achieve stable orbits. For the injection of the two satellite payloads into their intended stable orbits, the VTM stage had to fire for at least 20 seconds, to impart enough additional orbital velocity and altitude corrections. Instead the VTM kicked-in at 653.5s and shut itself down at 653.6s, post lift-off.[61] Following the partial firing of the VTM stage, the EOS 02 was released at 738.5s and AazadiSAT at 788.4s, post-liftoff. These failures transpired, resulting in the satellites entering an unstable orbit and subsequently destroyed upon reentry.

SSLV launch statistics

Further information: List of SSLV launches

Launch statistics

  •   Failure
  •   Partial failure
  •   Success
  •   Planned
Decade-wise summary of SSLV launches
Decade Successful Partial success Failure Total
2020s 1 0 1 2

See also


  1. ^ "SSLV MANUFACTURING". / Retrieved 7 August 2022.
  2. ^ a b "Satellite Launch Vehicle" (PDF). 16 December 2021. The development of SSLV is in the final stages and the first developmental flight of SSLV is targeted during the first quarter of 2022. The Government has sanctioned a total cost of Rs.169.07 Crores for the development project including the development & qualification of the vehicle systems and the flight demonstration through three development flights (SSLV-D1, SSLV-D2 & SSLV-D3)
  3. ^ a b "ISRO readying for low cost satellite launch vehicles". Retrieved 31 January 2020.
  4. ^ a b "Chandrayaan-2 Mission planned for middle of April". @businessline. 11 January 2019. Retrieved 28 July 2019.
  5. ^ "Why ISRO's maiden SSLV mission failed despite successful launch of new rocket". 8 August 2022. Retrieved 13 August 2022.
  6. ^ "ISRO is developing a small rocket to cash in on the small-satellite boom". Retrieved 2 September 2018.
  7. ^ a b c d "SSLV technical brochure V12" (PDF). 20 December 2019. Archived (PDF) from the original on 20 December 2019. Retrieved 20 December 2019.
  8. ^ a b Indian Space Research Organisation [@ISRO] (1 August 2022). "The launch of the SSLV-D1/EOS-02 Mission is scheduled for Sunday, August 7, 2022, at 9:18 am (IST) from Satish Dhawan Space Centre (SDSC), Sriharikota. ISRO invites citizens to the Launch View Gallery at SDSC to witness the launch" (Tweet). Retrieved 1 August 2022 – via Twitter.
  9. ^ a b c d "SSLV-D1/EOS-2 Mission Brochure" (PDF). Archived from the original (PDF) on 3 August 2022. Retrieved 4 August 2022.
  10. ^ a b c d e f g h "Small Satellite Launch Vehicle". Retrieved 5 November 2021.
  11. ^ Gunter's space page: SSLV
  12. ^ "SSLV". Retrieved 9 December 2018.
  13. ^ "Department of Space presentation on 18 January 2019" (PDF). 18 January 2019. Retrieved 30 January 2019.
  14. ^ U., Tejonmayam (7 August 2022). "SSLV-D1/EOS-02 mission: Rocket injected satellites but orbit achieved is less than expected, Isro says". The Times of India. Retrieved 7 August 2022.
  15. ^ Kumar, Chethan (19 July 2022). "Another Chandrayaan-3 test done on Sunday; SSLV launch planned for August". The Times of India. Retrieved 19 July 2022.
  16. ^ a b Service, Tribune News. "ISRO plans to launch new rocket before December 2020". Tribuneindia News. Retrieved 7 October 2020.
  17. ^ "Successful flight of Small Satellite Launch Vehicle (SSLV)". Press Information Bureau. 10 February 2023. Retrieved 14 February 2023.
  18. ^ a b "Design, Fabrication, Integration, Testing, Supply and Commissioning of Vehicle Telecommand Systems" (PDF). 16 September 2020. Archived from the original (PDF) on 6 August 2022. The proposed systems will be used as a part of new commanding requirement for Small Satellite Launch Vehicle (SSLV) Launch Complex (SLC) Site at Kulasekarapatnam, Tamilnadu.
  19. ^ a b "Episode 90 – An update on ISRO's activities with S. Somanath and R. Umamaheshwaran". AstrotalkUK. 24 October 2019. Retrieved 30 October 2019.
  20. ^ a b "India to get its second spaceport, land acquisition work begins in Tamil Nadu | India News - Times of India". The Times of India.
  21. ^ ""Industrialised" PSLV by 2022". The Hindu. 25 January 2020. ISSN 0971-751X. Retrieved 25 January 2020.
  22. ^ Sorensen, Jodi (6 August 2019). "Spaceflight Inc. Purchases and Fully Manifests First-Ever Commercial SSLV Mission from NewSpace India Limited (NSIL), the Commercial Arm of ISRO, India". Spaceflight. Archived from the original on 6 August 2019. Retrieved 6 August 2019.
  23. ^ a b Singh, Surendra (4 May 2018). "ISRO to rope in industry majors for mini-PSLV project". The Times of India. Retrieved 2 September 2018.
  24. ^ IANS (2 September 2018). "There's big money to make in space business for Indian firms: Antrix chief". Business Standard India. Retrieved 2 September 2018.
  25. ^ "India's 19 upcoming missions, and ISRO's Small Satellite Launch Vehicle (SSLV)". SpaceTech Asia. 28 August 2018. Retrieved 2 September 2018.
  26. ^ "ISRO developing vehicle to launch small satellites". Frontline. Retrieved 23 July 2021.
  27. ^ "Design for Small Satellite Launch Vehicle ready". The Hindu. 21 December 2018. Retrieved 21 December 2018.
  28. ^ Ramachandran, R. (26 August 2022). "First SSLV flight fails to put satellites in correct orbit". Retrieved 31 August 2022. According to a former ISRO scientist, the VTM can correct for a velocity shortfall of up to 172 metres/s. The rocket used for SSLV-D1 was a 34 m tall, 2 m diameter vehicle having a lift-off mass of 120 t.
  29. ^ SSLV-D1/EOS-02 Mission Video_English. 6 August 2022. Event occurs at 2 minute 30 seconds.
  30. ^ "Expression of Interest for Manufacturing of Composite motor cases of ISRO's launch vehicles" (PDF). 19 February 2020. Archived from the original (PDF) on 5 June 2020. Retrieved 6 August 2022. It may be specifically noted that process toolings of composite motor case for 2nd stage of SSLV is interchangeable with composite motor case for 3rd stage of PSLV to maximum extent.
  31. ^ SHAR Director Rajarajan Press Meet. 15 August 2022. Event occurs at 2 minutes 40 seconds. Two solid stages are new, fully developed. That is SS1 with 85-90 tonnes and SS3 with 4.5 tonnes whereas SS2 is almost identical to the HPS3 of PSLV.
  32. ^ "ORF on Twitter". twitter,com. Retrieved 2 September 2018.
  33. ^ Narayan Prasad (4 July 2018), Dr. Somnath on ISRO's Roadmap and Indian Launch Vehicles at Toulouse Space Show 2018, retrieved 2 September 2018
  34. ^ "Indian Space Research Organisation". Retrieved 5 June 2023.
  35. ^ "Message from Chairman's desk". Indian Space Research Organisation. 1 January 2019. Archived from the original on 2 January 2019. Retrieved 30 October 2019.
  36. ^ "TENDER NOTICE NO. SDSC SHAR/Sr.HPS/PT/13/2019-2020" (PDF). ISRO. Archived from the original (PDF) on 16 August 2019. Retrieved 30 October 2019. REQUEST FOR PROPOSAL (RFP) FOR SUPPLY, INSTALLATION AND COMMISSIONING OF RAIL TRACK FOR SLC PROJECT
  37. ^ "TENDER NOTICE NO. SDSC SHAR/Sr.HPS/PT/RO/03/2019-2020" (PDF). Archived from the original (PDF) on 6 September 2019. Retrieved 30 October 2019. REQUEST FOR PROPOSAL (RFP) FOR PROCUREMENT, MANUFACTURE, SUPPLY, TESTING and COMMISIONING [sic] OF SELF PROPELLED UNITS FOR SLC
  38. ^ "TENDER NOTICE NO. SDSC SHAR/Sr.HPS/PT/11/2019-2020" (PDF). ISRO. Archived from the original (PDF) on 16 August 2019. Retrieved 30 October 2019. RFP document for Supply of Stainless Steel Tanks
  39. ^ "ISRO's Second Spaceport, for New SSLV Rocket, to Come up in Tamil Nadu". The Wire. Retrieved 8 January 2020.
  40. ^ 4 IAF Pilots Selected, Design Phase Of Manned Mission Over (Video). 2 January 2020. Event occurs at 8 minutes.
  41. ^ Nagappa, Rajaram (December 2015). "The Promise of Small Satellites for National Security" (PDF). Archived (PDF) from the original on 14 January 2017. Retrieved 21 March 2022. By appropriate choice from among the solid propellant stages available with ISRO and DRDO, a launch vehicle could be configured and designated Small Satellite Launch Vehicle (SSLV-1). The performance of SSLV-1 was estimated using the in house developed trajectory-modelling programme QuoVadis. The performance runs show that SSLV-1 is capable of putting a 350 kg satellite in a polar orbit of 511 km x 497 km orbit and a 400 kg satellite in an orbit of 425 x 401 km (higher payloads are possible in equatorial orbit). This payload capability allows the launch of microsatellites with optical imaging and radar imaging payloads as well as individual intelligence satellites. Satellite life for the 400 kg mass satellite may be short in the 400 km orbit.
  42. ^ "NSSS 2016". 7 February 2016. Archived from the original on 7 February 2016.
  43. ^ "Future of Space Transportation by S. Somanath (Director, Liquid Propulsion Systems Centre)" (PDF). 7 February 2016. Archived from the original (PDF) on 7 February 2016.
  44. ^ Surendra Singh (22 November 2017). "Isro news: A rocket that can be made in 3 days | India News - Times of India". The Times of India. Retrieved 20 March 2022.
  45. ^ Rajwi, Tiki (21 December 2018). "Design for Small Satellite Launch Vehicle ready". The Hindu. ISSN 0971-751X. Retrieved 20 March 2022.
  46. ^ "SDSC-SHAR Website". 1 January 2021. Archived from the original on 1 January 2021. Retrieved 14 March 2022.
  47. ^ "చిన్న ఉపగ్రహ వాహకనౌక మోటారులో సాంకేతికలోపం". (in Telugu). Retrieved 23 March 2021.
  48. ^ "Department of Space, Annual Report 2021-22" (PDF). 27 April 2022. Archived from the original (PDF) on 27 April 2022. The first static test of SS1 solid motor was conducted and the performance of SS1 ignition system, propellant system and Flex Nozzle Control (FNC) system was evaluated. Various design modifications have been incorporated to resolve the anomalies observed in the first static test (…)
  49. ^ a b "Static test of first stage solid motor of India's mini rocket SSLV unsuccessful". The Economic Times. Retrieved 23 March 2021.
  50. ^ "Monthly Summary of Department of space for the month of August 2021" (PDF). 29 September 2021. Archived from the original on 29 December 2021.
  51. ^ "Ground testing of Solid Booster Stage (SS1) for Small Satellite Launch Vehicle (SSLV)". ISRO. 14 March 2022. Archived from the original on 20 March 2022. Retrieved 14 March 2022.
  52. ^ "RFP to make small rocket SSLV to be issued after 3/4 successful launches". Ahmedabad Mirror. Retrieved 15 March 2022.
  53. ^ "SSLV-D1/EOS-02 Mission - ISRO". Archived from the original on 7 August 2022. Retrieved 7 August 2022.
  54. ^ Indian Space Research Organization [@isro] (7 August 2022). "SSLV-D1/EOS-02 Mission: Maiden flight of SSLV is completed. All stages performed as expected. Data loss is observed during the terminal stage. It is being analysed. Will be updated soon" (Tweet) – via Twitter.
  55. ^ Indian Space Research Organization [@isro] (7 August 2022). "SSLV-D1/EOS-02 Mission update: SSLV-D1 placed the satellites into 356 km x 76 km elliptical orbit instead of 356 km circular orbit. Satellites are no longer usable. 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 analyse 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" (Tweet) – via Twitter.
  56. ^ a b "SSLV-D2/EOS-07 Mission: Second Developmental Flight of SSLV". Retrieved 5 February 2023.
  57. ^ Subramanian, T. s (11 August 2022). "ISRO chief S. Somanath interview | 'An anomaly for two seconds led to SSLV mission's underperformance'". The Hindu. ISSN 0971-751X. Retrieved 12 August 2022.
  58. ^ "ISRO's Maiden Small Satellite Rocket Flight Ends in Doubt After Engine Fails to Fire". The Wire. Retrieved 7 August 2022.
  59. ^ Clark, Stephen. "India's new small satellite launcher fails to put satellites into correct orbit – Spaceflight Now". Retrieved 8 August 2022.
  60. ^ SSLV-D1/EOS-02 Mission launch is scheduled for Aug 7, 2022 at 9:18 hrs IST from SDSC, Sriharikota, 6 August 2022, retrieved 8 August 2022
  61. ^ SSLV-D1/EOS-02 Mission launch is scheduled for Aug 7, 2022 at 9:18 hrs IST from SDSC, Sriharikota, 6 August 2022, retrieved 8 August 2022