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Typical IRNSS series one spacecraft
Mission typeNavigation
COSPAR ID2017-051A Edit this at Wikidata
SATCAT no.42928
Mission durationPlanned: 10 years
Spacecraft properties
ManufacturerISRO Satellite Centre
Space Applications Centre
Alpha Design et al.[1]
Launch mass1,425 kilograms (3,142 lb)
Dry mass594.35 kilograms (1,310.3 lb)
Power1671 watts
Start of mission
Launch date31 August 2017, 13:30 UTC
RocketPSLV-XL C39
Launch siteSatish Dhawan SLP
End of mission
DisposalLaunch vehicle heatshield failure[2]
Decay date2 March 2019
Orbital parameters
Reference systemGeocentric

IRNSS-1H was the eighth in the Indian Regional Navigational Satellite System (IRNSS) series of satellites, after IRNSS-1A, IRNSS-1B, IRNSS-1C, IRNSS-1D, IRNSS-1E, IRNSS-1F and IRNSS-1G. It was lost in the launch failure of PSLV-C39 on August 31, 2017.[3][4]


IRNSS-1H was India's first satellite to be assembled, integrated and tested by private firms under ISRO supervision and was intended to replace the failed IRNSS-1A and complete the NAVIC constellation of geosynchronous navigation satellites which is a ₹1420-crore independent regional navigation satellite system developed by India.[5][6]


  • Navigation payload in S band and L5 band, dual Helix Array Antenna (1.1 m diameter)
  • CDMA ranging payload in C band
  • Rubidium Atomic Frequency Standard
  • Corner Cube Retro Reflector for Laser Ranging

Propulsion: Conventional bipropellant system with Mono Methyl Hydrazine as fuel and Mixed Oxides of Nitrogen (MON-3) as oxidizer.[7]

  • Twelve 22N thrusters.
  • One 440N Liquid Apogee Motor (LAM)
  • Two 390 litres propellant tanks
  • One 67 litre pressurant tank with CFRP overwrap and Titanium liner.


PSLV-C39 carrying IRNSS-1H was using XL variant of Polar Satellite Launch Vehicle on its forty-first flight. Launch occurred as scheduled at 19:00 IST or 13:30 UTC, 31 August 2017 from Second Launch Pad of SDSC (SHAR) aiming for orbit of 284 × 20,650 km (Sub GTO) with 19.2° inclination. Vehicle performed initial flight sequences as planned but 203 seconds into flight, the payload fairing jettison event was not accomplished. Excluding this mid-flight malfunction, rest of the planned flight sequences including spacecraft separation at 17 minutes and 56 seconds occurred nominally but due to extra 1182 kg mass of fairing,[8] target orbit could not be achieved leaving the combined assembly of PSLV upper-stage (PS4), enclosed payload fairing and trapped IRNSS-1H spacecraft in 167.4 × 6554.8 km orbit with 19.18° inclination.[9][10][11] Liquid Apogee Motor (LAM) of IRNSS-1H was fired to help it come out of the payload fairing and to consume the propellants and passivate the spacecraft.[8]

PSLV payload fairing or heatshield

Prior to PSLV C39 / IRNSS-1H, last launch failure involving a PSLV happened 24 years ago in 1993, following which many variants of PSLV rockets have had 39 successful launches.[12]

Cause of failure[edit]

PSLV-C39 payload fairing separation mechanism consisted of horizontal and vertical jettisoning system. At the scheduled time during flight separation command was issued and the horizontal jettisoning system functioned nominally but the vertical jettisoning system malfunctioned and subsequently two halves of the payload fairing could not move apart. The cause of malfunction was identified as non-initiation of detonation in pyro device of vertical jettisoning system.[13][14]

Orbit decay[edit]

Combined assembly of PSLV fourth stage, payload fairings and enclosed IRNSS-1H spacecraft within it weighed between 2675 and 3480 kg and re-entered Earth's atmosphere around 19:23 UTC on 2 March 2019 over Vanuatu.[8]

See also[edit]


  1. ^ "IRNSS-1H: Isro to launch India's first satellite jointly built with pvt cos today". Retrieved 19 December 2019. This satellite is the first of the two satellites - being contracted by Isro to a consortium of small firms led by Alpha Design Technologies, a Bengaluru-based aerospace firm.
  2. ^ "IRNSS-1H launch from Sriharikota unsuccessful: ISRO". The Indian Express. 31 August 2017. Retrieved 31 August 2017.
  3. ^ "ISRO to launch a new navigation satellite on August 31". The Indian Express. 24 August 2017.
  4. ^ "PSLV-C39/IRNSS-1H Mission - ISRO". ISRO. Archived from the original on 2017-09-21. Retrieved 2017-08-24.
  5. ^ "IRNSS-1H set to launch on Thursday". The Hindu. 2017-08-30. ISSN 0971-751X. Retrieved 2019-12-19.
  6. ^ "1 tonne of extra weight doomed PSLV mission". The Times of India. 2 September 2017.
  7. ^ a b "SALIENT FEATURES OF IRNSS 1H". Retrieved 2019-12-19.
  8. ^ a b c Singh, Satyendra (11 December 2019). "IRNSS-1H/PSLV-C39 Orbit Evolution and Re-entry Analysis" (PDF). Retrieved 19 December 2019.
  9. ^ "heat shield". hindustan times. September 2017. Retrieved 1 September 2017.
  10. ^ "Two-Decade Success Streak Ends with PSLV Launch Failure on IRNSS-1H Mission – PSLV C39 | Spaceflight101". 31 August 2017. Retrieved 2019-12-19.
  11. ^ Clark, Stephen. "Indian navigation satellite stranded on rocket after launch – Spaceflight Now". Retrieved 2019-12-19.
  12. ^ "ISRO's IRNSS-1H fiasco: Failures are common in space missions, but India can't afford them at this juncture". September 2017.
  13. ^ "Government of India, Department of Space, Rajya Sabha, Unstarred Question Number. 773" (PDF). 8 February 2018. Retrieved 19 December 2019. The 41st flight of PSLV (PSLV-C39) that took place on August 31, 2017 with Indian Regional Navigational Satellite (IRNSS-1H weighing 1425 kg) could not reach the designated orbit, due to non-separation of Payload Fairing (also known as heat shield) during the 2nd stage of the flight. The root cause of the failure was understood after analysing the various flight and ground test data in more detail. For the Payload Fairing separation to happen successfully, the horizontal and vertical jettisoning system needs to function. Based on the flight data, it was observed that the command for horizontal and vertical jettisoning system was successfully issued. Though the horizontal jettisoning system functioned normally, there was malfunctioning of the vertical jettisoning system, due to which the Payload Fairing did not separate. The cause for the malfunctioning was the non-initiation of detonation in the vertical jettisoning system.
  14. ^ "Pyro devices to blame for PSLV failure: ISRO". The Hindu. 2017-09-23. ISSN 0971-751X. Retrieved 2019-12-19.

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