PSLV Orbital Experiment Module
{{Short description|Satellite bus derived out of launch vehicle upper stage}}
{{Use dmy dates|date=July 2023}}
{{Infobox spaceflight
| name = PSLV Orbital Experimental Module
| names_list = PS4 Orbital Platform
| image = PSLV-C11_Fourthstage.jpg
| image_caption = Unmodified PSLV fourth stage for PSLV-C11 campaign.
| mission_type = Technology
| dry_mass = ~920 kg
| payload_mass = up to 30 kg
| dimensions = Length: 3 meter {{line break}} Diameter: 2 meter
| power = 200 to 500 watts
}}
PSLV Orbital Experiment Platform (POEM) also known as PSLV Stage 4 Orbital Platform (PS4-OP){{Cite web |title=Payloads |url=https://www.isro.gov.in/Payloads.html |access-date=2023-07-24 |website=www.isro.gov.in |archive-date=24 July 2023 |archive-url=https://web.archive.org/web/20230724215843/https://www.isro.gov.in/Payloads.html |url-status=live }} is an orbital micro-gravity test bed based on spent fourth stage of PSLV. By adding modular subsystems for power generation, communication and stabilization like photovoltaic cells, Telemetry and Telecommand (TT&C) package, attitude control system, data storage etc to the PSLV fourth stage, it can function as a satellite bus. This augmented stage can then host payloads for up to six months while in orbit, making it useful for qualifying components, gaining space heritage and conduct experiments in micro-gravity conditions. Usually the fourth stage of PSLV is discarded after deployment of satellite and remains in orbit for a significant duration in a passive state as a piece of space debris.
Objective
POEM or PS4-OP was conceived by VSSC/ISRO to help Indian academia and start-ups by providing a low cost platform with essential subsystems to support their payloads hence lowering the barriers of reaching orbit. POEM off-loads the burden of designing, qualifying, procuring a satellite bus, setting up a ground station etc. which reduces the development time and costs associated with using space-grade components thus allowing entities to just focus on payload.
History
PSLV fourth stage or PS4 has often been used to carry non-separable payloads like AAM on PSLV-C8,{{cite web |title=PSLV C8 / AGILE brochure |url=https://www.isro.gov.in/sites/default/files/flipping_book/PSLV-C8/files/assets/common/downloads/publication.pdf |url-status=dead |archive-url=https://web.archive.org/web/20200223011646/https://www.isro.gov.in/sites/default/files/flipping_book/PSLV-C8/files/assets/common/downloads/publication.pdf |archive-date=23 February 2020 |access-date=23 February 2020}} Rubin 9.1/Rubin 9.2 on PSLV-C14{{cite web |title=PSLV C14/Oceansat-2 brochure |url=https://www.isro.gov.in/sites/default/files/flipping_book/PSLV-C14/files/assets/common/downloads/publication.pdf |url-status=dead |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 |archive-date=6 August 2020 |access-date=23 February 2020}} and mRESINS on PSLV-C21{{cite web |title=Space-India July 2012 to August 2013 |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 |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 |archive-date=6 August 2020 |access-date=23 February 2020}} etc. but such payloads could be supported only for a very short duration as PS4 lacked the capacity to generate power and maintain attitude stability. So it was proposed to augment PS4 with modular subsystems to convert it into a long duration orbital platform after completion of primary mission.{{cite web |date=21 February 2019 |title=Opportunities for science experiments in the fourth stage of India's PSLV |url=http://www.unoosa.org/documents/pdf/copuos/stsc/2019/tech-55E.pdf |url-status=live |archive-url=https://ghostarchive.org/archive/20221009/http://www.unoosa.org/documents/pdf/copuos/stsc/2019/tech-55E.pdf |archive-date=2022-10-09}}{{cite web |date=15 June 2019 |title=Announcement of Opportunity (AO) for Orbital platform: an avenue for in-orbit scientific experiments |url=https://www.isro.gov.in/sites/default/files/orbital_platform-_ao.pdf |url-status=dead |archive-url=https://web.archive.org/web/20200806072033/https://www.isro.gov.in/sites/default/files/orbital_platform-_ao.pdf |archive-date=6 August 2020 |access-date=23 February 2020}}{{cite web |last=Kumar |first=Chethan |title=2 days after Space Station news, Isro calls for "docking experiments" on PSLV stage-4 |url=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 |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 |archive-date=24 August 2019 |access-date=23 February 2020 |work=The Times of India}}
In 2017 as an early demonstration on PSLV-C37/Cartosat-2D{{Cite AV media |url=https://www.youtube.com/watch?v=fujsQ5teHJI&t=4094s |title=The launch of PSLV–C37/CARTOSAT – 2 Series Satellite - Live |date=15 February 2017 |time=1 hour 08 minutes 14 seconds}} and PSLV-C38/Cartosat-2E campaigns,{{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 |url-status=live |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 |archive-date=21 September 2022 |access-date=2022-06-27 |website=www.isro.gov.in |language=en}} PS4 was kept operational and monitored for over ten orbits after completion of its primary mission of deploying spacecraft.{{cite web |title=Department of Space Annual Report 2017-18 |url=https://www.isro.gov.in/sites/default/files/article-files/node/9805/annualreport2017-18.pdf |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}}{{cite web |last=rajasekhar |first=pathri |date=2017-06-20 |title=Isro to lower rocket's altitude |url=https://www.deccanchronicle.com/science/science/200617/isro-to-lower-rockets-altitude.html |url-status=live |archive-url=https://web.archive.org/web/20200806095054/https://www.deccanchronicle.com/science/science/200617/isro-to-lower-rockets-altitude.html |archive-date=6 August 2020 |access-date=23 February 2020 |publisher=Deccan Chronicle}} Fourth stage on PSLV-C38 hosted IDEA (Ionization Density and Electric field Analyzer) as a non-separable payload by Space Physics Laboratory of VSSC, two other non-separable payloads were mAMP and 'Earth Pointing Platform'.{{Cite AV media |url=https://www.youtube.com/watch?v=bwV0S7uEPMg&t=3036s |title=5th Manohar Parrikar Vidnyan Mahotsav: Talk By ISRO Chairman Dr. S. Somanath |date=13 December 2023 |time=50 min. 36 sec.}}
File:Render of PS4 Orbital Platform payload deck.webp
In January 2019, PSLV-C44/Microsat-R became the first campaign where PS4 functioned as an independent orbital platform for short duration as the provisions for on-board power generation capacity were not yet made.{{cite news |last=Rajwi |first=Tiki |date=2019-01-12 |title=PSLV lift-off with added features |newspaper=The Hindu |url=https://www.thehindu.com/news/national/kerala/pslv-lift-off-with-added-features/article25981654.ece |url-status=live |access-date=23 February 2020 |archive-url=https://web.archive.org/web/20200806161530/https://www.thehindu.com/news/national/kerala/pslv-lift-off-with-added-features/article25981654.ece |archive-date=6 August 2020 |issn=0971-751X}} It hosted a 1U cubesat called KalamSAT-V2 as a non-separable payload by Space Kidz India based on Interorbital Systems kit.{{cite web |title=PSLV-C44 - ISRO |url=https://www.isro.gov.in/launcher/pslv-c44 |url-status=dead |archive-url=https://web.archive.org/web/20190117013408/https://www.isro.gov.in/launcher/pslv-c44 |archive-date=17 January 2019 |access-date=26 June 2020 |website=isro.gov.in}}{{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}}{{cite web |last=Singh |first=Surendra |date=16 December 2018 |title=In a first, ISRO will make dead rocket stage "alive" in space for experiments |url=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 |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 |archive-date=8 November 2020 |access-date=23 February 2020 |work=The Times of India}} Later in April, the fourth stage on PSLV-C45/EMISAT{{Cite web |title=PSLV-C45/EMISAT Mission Press-kit |url=https://www.isro.gov.in/sites/default/files/pslv-c45_launch_kitv5.0_fn_23.03.19.pdf |archive-url=https://web.archive.org/web/20190323093804/https://www.isro.gov.in/sites/default/files/pslv-c45_launch_kitv5.0_fn_23.03.19.pdf |archive-date=23 March 2019 |access-date=23 July 2023 |url-status=dead }} had its own power generation capacity as it was augmented with an array of fixed solar cells wrapped around the propellant tank of PS4 generating about 200 watts of power.{{cite web |last=Clark |first=Stephen |title=Indian military satellite, 20 more Planet imaging CubeSats launched by PSLV |url=https://spaceflightnow.com/2019/04/01/indian-military-satellite-20-more-planet-imaging-cubesats-aboard-successful-pslv-launch/ |url-status=live |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/ |archive-date=6 April 2019 |access-date=2020-02-23 |publisher=Spaceflight Now}}{{Cite AV media |url=https://www.youtube.com/watch?v=lGyCpYFS90o&t=81s |title=Press briefing by S Somanath (Chairman, ISRO) |date=22 April 2023 |time=1 minutes 22 seconds}}{{Cite web |title=PSLV-C45/EMISAT Mission Curtain Raiser video (English) |url=https://www.isro.gov.in/mission_PSLV_C45_CameraView.html |access-date=2023-07-23 |website=www.isro.gov.in |archive-date=26 July 2023 |archive-url=https://web.archive.org/web/20230726171613/https://www.isro.gov.in/mission_PSLV_C45_CameraView.html |url-status=live }} Three payloads hosted on PS4-OP were, Advanced Retarding Potential Analyzer for Ionospheric Studies (ARIS 101F) by IIST,{{cite web |title=Department of Avionics, R. Sudharshan Kaarthik, Ph.D (Assistant Professor) |url=https://www.iist.ac.in/avionics/sudharshan.kaarthik |url-status=live |archive-url=https://web.archive.org/web/20200213005932/https://www.iist.ac.in/avionics/sudharshan.kaarthik |archive-date=13 February 2020 |access-date=23 February 2020}} experimental AIS payload by ISRO and AISAT by Satellize.{{cite web |title=Exseed Sat-2 |url=https://satellize.com/index.php/exseed-sat-2/ |url-status=live |archive-url=https://web.archive.org/web/20200223011624/https://satellize.com/index.php/exseed-sat-2/ |archive-date=23 February 2020 |access-date=23 February 2020 |publisher=Satellize}} To function as an orbital platform, fourth stage was put in spin-stabilized mode using its RCS thrusters.{{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 |url-status=live |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}} PS4-OP on this campaign had mission life of 3 months and AISAT payload onboard was operational for almost a year. According to ISRO, the PS4-OP can transmit commands and data to sustain the payloads and regulate its location in three different orientations.{{Cite web |last=Linganna |first=Girish |date=3 January 2025 |title=While POEM-4 Experiments Run, SPADEX Prepares for Docking Day |url=https://www.india.com/news/india/while-poem-4-experiments-run-spadex-prepares-for-docking-day-7510978/ |access-date=2025-01-03 |website=india.com |language=en}}
After these initial testing campaigns, ISRO issued an Announcement of Opportunity in June 2019 to carry out in-orbit scientific experiments on PS4 orbital platform. And in following years POEM-1 aboard PSLV-C53/DS-EO campaign in June 2022{{Cite web |title=NSIL's Second Dedicated commercial launch "PSLV-C53/ DS-EO Mission" successfully accomplished on 30th June 2022 |url=https://www.nsilindia.co.in/sites/default/files/Press%20Release%20-%20PSLV%20C-53%20DS-EO%20Mission.pdf |archive-url=https://web.archive.org/web/20230518082810/https://www.nsilindia.co.in/sites/default/files/Press%20Release%20-%20PSLV%20C-53%20DS-EO%20Mission.pdf |archive-date=18 May 2023}} and POEM-2 aboard PSLV-C55/TeLEOS-2 campaign in April 2023 were launched.{{Cite web |title=India's PSLV launches with two Singaporean satellites – Spaceflight Now |url=https://spaceflightnow.com/2023/04/22/indias-pslv-launches-with-two-singaporean-satellites/ |access-date=2023-07-26 |language=en-US |archive-date=6 June 2023 |archive-url=https://web.archive.org/web/20230606165526/https://spaceflightnow.com/2023/04/22/indias-pslv-launches-with-two-singaporean-satellites/ |url-status=live }} Both of these orbital platforms had mature configurations utilizing 3-axis stabilization and on-board power generation capacity.{{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}}{{Cite web |title=PSLV-C55/TeLEOS-2 mission press kit |url=https://www.isro.gov.in/media_isro/pdf/Missions/PSLVC55/PSLVC55TeLEOS.pdf |archive-url=https://web.archive.org/web/20230528023203/https://www.isro.gov.in/media_isro/pdf/Missions/PSLVC55/PSLVC55TeLEOS.pdf |archive-date=28 May 2023}}
In July 2023, Indian National Space Promotion and Authorisation Centre (IN-SPACe) issued an announcement of opportunity inviting payloads to be hosted aboard upcoming POEM campaigns tentatively scheduled between November 2023 and June 2024.{{Cite web |title=IN-SPACe Announcement of Opportunity for hosting of payloads on POEM Page - IN-SPACe |url=https://www.inspace.gov.in/inspace?id=inspace_hosting_payloads_on_poem_page |access-date=2023-07-25 |website=www.inspace.gov.in |archive-date=26 July 2023 |archive-url= https://archive.today/20230726172619/https://www.inspace.gov.in/inspace?id=inspace_hosting_payloads_on_poem_page|url-status=live }}
On 1 January 2024, POEM-3 was launched along with XpoSat on PSLV-C58 hosting ten payloads. The stage was lowered from a 650 km (circular) injection orbit of XpoSAT to a 350 km circular orbit for POEM-3 operations.{{Cite web |last=PTI |date=2024-01-01 |title=ISRO Fires Fourth Stage Of PSLV-C58 Twice To Hold Scientific Experiments |url=https://www.ndtvprofit.com/technology/isro-fires-fourth-stage-of-pslv-c58-twice-to-hold-scientific-experiments |access-date=2024-01-01 |website=NDTV Profit |language=en}} POEM-3 re-entered atmosphere on 21 March 2024 over the Pacific Ocean after having accomplished its objectives by February and thus leaving behind no space-debris from the launch.{{Cite web |title=PSLV accomplishes zero orbital debris mission |url=https://www.isro.gov.in/PSLVC58_POEM3_accomplish_zero_orbital_debris_mission.html |archive-url=https://web.archive.org/web/20240325150554/https://www.isro.gov.in/PSLVC58_POEM3_accomplish_zero_orbital_debris_mission.html |archive-date=25 March 2024 |access-date=2024-03-26 |website=www.isro.gov.in}}{{Cite web |title=POEM-3 Mission achieves all its Payload objectives |url=https://www.isro.gov.in/POEM-3_Mission_achieves_Payload_objectives.html |access-date=2024-03-26 |website=www.isro.gov.in}}
On 30 December 2024, POEM-4 was launched with 24 non-separable payloads as part of the PSLV-C60/SpaDeX mission.{{Cite web |title=PSLV-C60 SPADEX Mission Press-kit |url=https://www.isro.gov.in/media_isro/pdf/Missions/PSLVC60/PSLVC60-mission-brochure-english.pdf}}{{Cite web |title=POEM-4 in PSLV-C60 / SpaDeX Mission |url=https://www.isro.gov.in/POEM_4_Payloads_spadex.html |access-date=2025-02-09 |website=www.isro.gov.in}} The PS4 stage was restarted twice to lower the orbit from 470 km to 350 km circular orbit for POEM-4 operations.{{Cite news |last=C.S |first=Hemanth |date=2024-12-31 |title=ISRO’s PSLV-C60 Mission: 10 payload from non-government entities successfully deployed on POEM-4 |url=https://www.thehindu.com/sci-tech/science/pslv-c60-mission-10-payload-from-non-government-entities-successfully-deployed-of-on-poem-4/article69046002.ece |access-date=2025-02-09 |work=The Hindu |language=en-IN |issn=0971-751X}}
Platform capabilities
Specifications and capabilities of PSLV fourth stage based orbital platform which may improve over time.{{Cite AV media |url=https://www.youtube.com/watch?v=J7XKKZMrkB4&t=475s |title=DAY 1 {{!}} PS 5 {{!}} SESSION A |date=31 Jan 2022 |time=8 minutes}}
- Mission life: Up to six months depending on left-over Helium pressurant in fourth stage.
- Maximum mass of payload: 30 kg
- Maximum size: About 3U, depends on spare area available for a particular mission and mounting location.
- Maximum power of payload: 200 to 500 watts
- Power bus: 28 Volts
- Maximum data rate: 1 Mbps
- Pointing accuracy:
- During sunlit period: within ±1°
- During eclipse: ±5°
- Slew rate within 0.5° per second during stabilized regime.
- Data storage: 1GB
- TT&C: S-band
- Downlink at ISRO ground station
- Suitable for experiments requiring large Inertia and structure.
Missions
Gallery
File:PSLV-C53, DS-EO - Render of PSLV Orbital Experimental Module (POEM) without DLA upper.png|PSLV-C53/POEM-1
File:PSLV-C55, TeLEOS-2 - Render of POEM with solar panels deployed.webp|PSLV-C55/POEM-2
File:PSLV-C58, XPoSat - Render of POEM-3 orbital platform.png|PSLV-C58/POEM-3
File:PSLV-C60, SpaDEx — Render of POEM-4.png|PSLV-C60/POEM-4
See also
{{Commons category|PSLV Orbital Experiment Module}}
References
{{reflist}}
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{{Orbital launch systems}}