Editing Polar Satellite Launch Vehicle (section)

==== PS4 stage as orbital platform ====
{{Main|PSLV Orbital Experiment Module}}
PS4 has carried hosted payloads like AAM on PSLV-C8,<ref name=":6"/> [[Luxspace|Rubin 9.1]]/[[Rubin 9.2]] on PSLV-C14<ref>{{cite web|url=https://www.isro.gov.in/sites/default/files/flipping_book/PSLV-C14/files/assets/common/downloads/publication.pdf|url-status=dead|title=PSLV C14/Oceansat-2 brochure|access-date=23 February 2020|archive-date=6 August 2020|archive-url=https://web.archive.org/web/20200806094152/https://www.isro.gov.in/sites/default/files/flipping_book/PSLV-C14/files/assets/common/downloads/publication.pdf}}</ref> and mRESINS on PSLV-C21.<ref>{{cite web |url=https://www.dos.gov.in/sites/default/files/flipping_book/Space%20India%20July%2012-Aug%2013/files/assets/common/downloads/Space%20India%20July%2012-Aug%2013.pdf |url-status=dead |title=Space-India July 2012 to August 2013 |access-date=23 February 2020 |archive-date=6 August 2020 |archive-url=https://web.archive.org/web/20200806152719/https://www.dos.gov.in/sites/default/files/flipping_book/Space%20India%20July%2012-Aug%2013/files/assets/common/downloads/Space%20India%20July%2012-Aug%2013.pdf }}</ref> But now, PS4 is being augmented to serve as a long duration orbital platform after completion of primary mission. PS4 Orbital Platform (PS4-OP) will have its own power supply, telemetry package, data storage and attitude control for hosted payloads.<ref>{{cite web|url=http://www.unoosa.org/documents/pdf/copuos/stsc/2019/tech-55E.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://www.unoosa.org/documents/pdf/copuos/stsc/2019/tech-55E.pdf |archive-date=2022-10-09 |url-status=live|title=Opportunities for science experiments in the fourth stage of India's PSLV|date=21 February 2019}}</ref><ref>{{cite web|url=https://www.isro.gov.in/sites/default/files/orbital_platform-_ao.pdf|url-status=dead|title=Announcement of Opportunity (AO) for Orbital platform: an avenue for in-orbit scientific experiments|date=15 June 2019|access-date=23 February 2020|archive-date=6 August 2020|archive-url=https://web.archive.org/web/20200806072033/https://www.isro.gov.in/sites/default/files/orbital_platform-_ao.pdf}}</ref><ref>{{cite news|url=https://timesofindia.indiatimes.com/india/2-days-after-space-station-news-isro-calls-for-docking-experiments-on-pslv-stage-4/articleshow/69800354.cms|title=2 days after Space Station news, Isro calls for "docking experiments" on PSLV stage-4|first=Chethan|last=Kumar|work=The Times of India|date=15 June 2019 |access-date=23 February 2020|archive-date=24 August 2019|archive-url=https://web.archive.org/web/20190824073052/https://timesofindia.indiatimes.com/india/2-days-after-space-station-news-isro-calls-for-docking-experiments-on-pslv-stage-4/articleshow/69800354.cms|url-status=live}}</ref>

On [[PSLV-C37]] and [[PSLV-C38]] campaigns,<ref>{{Cite web |title=In-situ observations of rocket burn induced modulations of the top side ionosphere using the IDEA payload on-board the unique orbiting experimental platform (PS4) of the Indian Polar Orbiting Satellite Launch Vehicle mission - ISRO |url=https://www.isro.gov.in/situ-observations-of-rocket-burn-induced-modulations-of-top-side-ionosphere-using-idea-payload-board |access-date=2022-06-27 |website=www.isro.gov.in |language=en |archive-date=21 September 2022 |archive-url=https://web.archive.org/web/20220921000216/https://www.isro.gov.in/situ-observations-of-rocket-burn-induced-modulations-of-top-side-ionosphere-using-idea-payload-board |url-status=live }}</ref> as a demonstration PS4 was kept operational and monitored for over ten orbits after delivering spacecraft.<ref>{{cite web |url=https://www.isro.gov.in/sites/default/files/article-files/node/9805/annualreport2017-18.pdf|title=Department of Space Annual Report 2017-18|url-status=live|archive-url=https://web.archive.org/web/20180213093132/https://www.isro.gov.in/sites/default/files/article-files/node/9805/annualreport2017-18.pdf|archive-date=13 February 2018}}</ref><ref>{{cite web|url=https://timesofindia.indiatimes.com/india/in-a-first-isro-will-make-dead-rocket-stage-alive-in-space-for-experiments/articleshow/67067817.cms|title=In a first, ISRO will make dead rocket stage "alive" in space for experiments|first=Surendra|last=Singh|work=The Times of India|date=16 December 2018|access-date=23 February 2020|archive-date=8 November 2020|archive-url=https://web.archive.org/web/20201108132514/https://timesofindia.indiatimes.com/india/in-a-first-isro-will-make-dead-rocket-stage-alive-in-space-for-experiments/articleshow/67067817.cms|url-status=live}}</ref><ref>{{cite web|url=https://www.deccanchronicle.com/science/science/200617/isro-to-lower-rockets-altitude.html|title=Isro to lower rocket's altitude|last=rajasekhar|first=pathri|publisher=Deccan Chronicle|date=2017-06-20|access-date=23 February 2020|archive-date=6 August 2020|archive-url=https://web.archive.org/web/20200806095054/https://www.deccanchronicle.com/science/science/200617/isro-to-lower-rockets-altitude.html|url-status=live}}</ref>

[[PSLV-C44]] was the first campaign where PS4 functioned as independent orbital platform for short duration as there was no on-board power generation capacity.<ref>{{cite news|last=Rajwi|first=Tiki|url=https://www.thehindu.com/news/national/kerala/pslv-lift-off-with-added-features/article25981654.ece|title=PSLV lift-off with added features|date=2019-01-12|newspaper=The Hindu|issn=0971-751X|access-date=23 February 2020|archive-date=6 August 2020|archive-url=https://web.archive.org/web/20200806161530/https://www.thehindu.com/news/national/kerala/pslv-lift-off-with-added-features/article25981654.ece|url-status=live}}</ref> It carried KalamSAT-V2 as a fixed payload, a 1U CubeSat by Space Kidz India based on [[Interorbital Systems]] kit.<ref>{{cite web|title=PSLV-C44 - ISRO|url=https://www.isro.gov.in/launcher/pslv-c44|access-date=26 June 2020|website=isro.gov.in|archive-date=17 January 2019|archive-url=https://web.archive.org/web/20190117013408/https://www.isro.gov.in/launcher/pslv-c44|url-status=dead}}</ref><ref>{{cite tweet|number=1088526772109422592|user=interorbital|title=Congratulations to ISRO and SpaceKidzIndia on getting their CubeSat into orbit! The students modified their IOS CubeSat kit, complete w/ their own experiments!|author=Interorbital Systems|date=25 January 2019}}</ref>

On [[PSLV-C45]] campaign, the fourth stage had its own power generation capability as it was augmented with an array of fixed [[solar cell]]s around PS4 propellant tank.<ref>{{cite web|url=https://spaceflightnow.com/2019/04/01/indian-military-satellite-20-more-planet-imaging-cubesats-aboard-successful-pslv-launch/|title=Indian military satellite, 20 more Planet imaging CubeSats launched by PSLV|last=Clark|first=Stephen|publisher=Spaceflight Now|access-date=2020-02-23|archive-date=6 April 2019|archive-url=https://web.archive.org/web/20190406042135/https://spaceflightnow.com/2019/04/01/indian-military-satellite-20-more-planet-imaging-cubesats-aboard-successful-pslv-launch/|url-status=live}}</ref> The three payloads hosted on PS4-OP were the Advanced Retarding Potential Analyzer for Ionospheric Studies (ARIS 101F) by [[IIST]],<ref>{{cite web|url=https://www.iist.ac.in/avionics/sudharshan.kaarthik|title=Department of Avionics, R. Sudharshan Kaarthik, Ph.D (Assistant Professor)|access-date=23 February 2020|archive-date=13 February 2020|archive-url=https://web.archive.org/web/20200213005932/https://www.iist.ac.in/avionics/sudharshan.kaarthik|url-status=live}}</ref> an experimental [[Automatic identification system|AIS]] payload by ISRO, and AISAT by [[Satellize]].<ref>{{cite web|url=https://satellize.com/index.php/exseed-sat-2/|title=Exseed Sat-2|publisher=Satellize|access-date=23 February 2020|archive-date=23 February 2020|archive-url=https://web.archive.org/web/20200223011624/https://satellize.com/index.php/exseed-sat-2/|url-status=live}}</ref> To function as orbital platform, fourth stage was put in [[Spin-stabilisation|spin-stabilized]] mode using its RCS thrusters.<ref>{{Cite web |date=16 June 2021 |title=Opportunity for Scientific Experiments on PSLV Upper Stage Orbital Platform |url=https://www.unoosa.org/documents/pdf/psa/hsti/Hyper-Microgravity_Webinar2021/Hyper-Microgravity_Webinar2021/9_RegionalActivities/R._Senan_Hypermicrogravity_ISRO.pdf |archive-url=https://ghostarchive.org/archive/20221009/https://www.unoosa.org/documents/pdf/psa/hsti/Hyper-Microgravity_Webinar2021/Hyper-Microgravity_Webinar2021/9_RegionalActivities/R._Senan_Hypermicrogravity_ISRO.pdf |archive-date=2022-10-09 |url-status=live}}</ref>

On the [[PSLV-C53]] campaign, the PS4-OP is referred to as the [[PSLV-C53#PSLV Orbital Experimental Module|PSLV Orbital Experimental Module (POEM)]], and it hosted six payloads. POEM was the first PSLV fourth stage based orbital platform to be actively stabilised using Helium based cold gas thrusters after the primary mission and stage passivization.<ref>{{Cite web |last=Kumar |first=Chethan |date=June 25, 2012 |title=Bengaluru's Digantara, Hyderabad startup Dhruva become first to get IN-SPACe authorisation |url=https://timesofindia.indiatimes.com/india/bengaluru-digantara-hyderabad-startup-dhruva-become-first-to-get-in-space-authorisation/articleshow/92460375.cms |url-status=live |archive-url=https://web.archive.org/web/20220625153537/https://timesofindia.indiatimes.com/india/bengaluru-digantara-hyderabad-startup-dhruva-become-first-to-get-in-space-authorisation/articleshow/92460375.cms |archive-date=2022-06-25 |access-date=2022-06-26 |website=The Times of India |language=en}}</ref><ref>{{Cite web |title=PSLV-C53/DS-EO mission |url=https://www.isro.gov.in/sites/default/files/article-files/pslv-c53-ds-eo-mission/pslv-c53-ds-eo-mission-brochure-english/brochure_pslv_c53-ds-eo_mission_english.pdf |archive-url=https://web.archive.org/web/20220705162540/https://www.isro.gov.in/sites/default/files/article-files/pslv-c53-ds-eo-mission/pslv-c53-ds-eo-mission-brochure-english/brochure_pslv_c53-ds-eo_mission_english.pdf |archive-date=5 July 2022}}</ref><ref>{{Cite web |title=పీఎస్‌ఎల్‌వీ-సి53లో నూతన సాంకేతికత |url=https://www.eenadu.net/telugu-news/related-stories/general/2505/122117906 |url-status=live |archive-url=https://web.archive.org/web/20220706195945/https://www.eenadu.net/telugu-news/related-stories/general/2505/122117906 |archive-date=2022-07-06 |access-date=2022-07-06 |website=EENADU |language=te}}</ref><ref>{{Cite web |author=News9 Staff |date=2022-09-08 |title=Har Ghar Tiranga happened in Antriksh. ISRO did hoist the Indian flag in Space! |url=https://www.news9live.com/india/har-ghar-tiranga-happened-in-antriksh-isro-did-hoist-the-indian-flag-in-space-194691 |access-date=2022-09-09 |website=NEWS9LIVE |language=en |archive-date=9 September 2022 |archive-url=https://web.archive.org/web/20220909095750/https://www.news9live.com/india/har-ghar-tiranga-happened-in-antriksh-isro-did-hoist-the-indian-flag-in-space-194691 |url-status=live }}</ref>