IRNSS-1H

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.{{Cite news|url=https://www.thehindu.com/news/national/irnss-1h-set-to-launch-on-thursday/article19589102.ece|title=IRNSS-1H set to launch on Thursday|date=2017-08-30|work=The Hindu|access-date=2019-12-19|language=en-IN|issn=0971-751X}}{{cite news|url=http://timesofindia.indiatimes.com/india/not-just-trucks-india-even-overloads-its-rockets/articleshow/60332224.cms|title=1 tonne of extra weight doomed PSLV mission|website=The Times of India |date=2 September 2017 }}

Payload:{{Cite web|url=https://www.ursc.gov.in/navigation/html/irnss-1h.jsp|title=SALIENT FEATURES OF IRNSS 1H|website=www.ursc.gov.in|access-date=2019-12-19}}

• 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.

• 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,{{Cite web|url=https://www.hou.usra.edu/meetings/orbitaldebris2019/orbital2019paper/pdf/6159.pdf|title=IRNSS-1H/PSLV-C39 Orbit Evolution and Re-entry Analysis|last=Singh|first=Satyendra|date=11 December 2019|access-date=19 December 2019}} 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.{{cite web|title=heat shield|url=http://www.hindustantimes.com/science/isro-launch-unsuccessful-what-is-heat-shield-and-why-was-irnss-1h-satellite-not-released/story-hQ81GxorxtCvv7vYe9qyML.html|website=hindustan times|date=September 2017 |access-date=1 September 2017}}{{Cite web|url=http://spaceflight101.com/pslv-c39/pslv-launch-failure-irnss-h/|title=Two-Decade Success Streak Ends with PSLV Launch Failure on IRNSS-1H Mission – PSLV C39 {{!}} Spaceflight101|date=31 August 2017 |language=en-US|access-date=2019-12-19}}{{Cite web|url=https://spaceflightnow.com/2017/08/31/pslv-c39/|title=Indian navigation satellite stranded on rocket after launch – Spaceflight Now|last=Clark|first=Stephen|language=en-US|access-date=2019-12-19}} 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.

File:PSLV Heat Shield Model.jpg

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.{{cite web|url=http://www.firstpost.com/tech/news-analysis/isros-irnss-1h-fiasco-failures-are-common-in-space-missions-but-india-cant-afford-them-at-this-juncture-3998717.html|title=ISRO's IRNSS-1H fiasco: Failures are common in space missions, but India can't afford them at this juncture|date=September 2017 }}

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.{{Cite web|url=https://pqars.nic.in/annex/245/Au773.pdf|title=Government of India, Department of Space, Rajya Sabha, Unstarred Question Number. 773|date=8 February 2018|access-date=19 December 2019|quote=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.}}{{Cite news|url=https://www.thehindu.com/todays-paper/tp-national/pyro-devices-to-blame-for-pslv-failure-isro/article19738850.ece|title=Pyro devices to blame for PSLV failure: ISRO|date=2017-09-23|work=The Hindu|access-date=2019-12-19|language=en-IN|issn=0971-751X}}

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.

{{Portal|Spaceflight|India}}

• GPS-aided geo-augmented navigation (GAGAN)
• Satellite navigation

{{Reflist|2}}

• [http://www.isro.org/scripts/futureprogramme.aspx ISRO Future Programmes]

{{IRNSS satellites}}

{{Orbital launches in 2017}}

{{PSLV}}

Category:Spacecraft launched by India in 2017

Category:IRNSS satellites

Category:Spacecraft launched by PSLV rockets

Category:Satellite launch failures