CleanupBot II at 11:07, 14 August 2023

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{{Short description|Indian weather satellite}}
{{Infobox spaceflight
| auto = all
| name = Megha-Tropiques
| image = Render of Megha-Tropiques spacecraft in deployed configuration.png
| image_caption =
| mission_type = [[Weather satellite|Weather]]
| operator = [[ISRO]]/[[CNES]]
| website = {{url|http://meghatropiques.ipsl.polytechnique.fr/index.php}}
| COSPAR_ID = 2011-058A
| SATCAT = 37838
| mission_duration = Planned: 3 years<br />Final: 10 years, 5 months
| spacecraft_bus =
| manufacturer = [[ISRO]]
| dry_mass = 
| launch_mass = {{convert|1000|kg|lb|0}}
| power = 1325 [[Watt|W]]<ref name="eoportal" />
| launch_date = {{start-date|12 October 2011}}
| launch_rocket = [[Polar Satellite Launch Vehicle|PSLV-CA]] C18
| launch_site = [[Satish Dhawan Space Centre|Satish Dhawan]] [[Satish Dhawan Space Centre First Launch Pad|FLP]]
| launch_contractor = [[Indian Space Research Organisation|ISRO]]
| disposal_type = decommissioned
| deactivated = April 2022
| last_contact = 
| decay_date = 7 March 2023<ref name="isro-reentry" />
| orbit_epoch = 25 January 2015, 01:35:41 UTC<ref name="n2yo">{{cite web|url=http://www.n2yo.com/satellite/?s=37838|title=MEGHA-TROPIQUES Satellite details 2011-058A NORAD 37838|publisher=N2YO|access-date=25 January 2015}}</ref>
| orbit_reference = [[geocentric orbit|Geocentric]]
| orbit_periapsis = {{convert|860|km|mi}}<ref name="n2yo"/>
| orbit_apoapsis = {{convert|874|km|mi}}<ref name="n2yo"/>
| orbit_inclination = 19.98 degrees<ref name="n2yo"/>
| orbit_eccentricity = 0.0009922<ref name="n2yo"/>
| orbit_semimajor = {{convert|7238.45|km|mi}}<ref name="n2yo"/>
| orbit_period = 102.15 minutes<ref name="n2yo"/>
| apsis = gee
}}

'''Megha-Tropiques''' was a [[satellite]] mission to study the [[water cycle]] in the tropical atmosphere in the context of climate change.<ref>[http://meghatropiques.ipsl.polytechnique.fr/ Mission description] {{Webarchive|url=https://web.archive.org/web/20120213145729/http://meghatropiques.ipsl.polytechnique.fr/ }}. MEGHA-TROPIQUES: water cycle in the tropical atmosphere in the context of climate change.(Access date 06-21-2008)</ref> A collaborative effort between Indian Space Research Organisation ([[ISRO]]) and French Centre National d’Etudes Spatiales ([[CNES]]), Megha-Tropiques was successfully deployed into orbit by a [[PSLV]] rocket in October 2011.

Megha-Tropiques was initially scrapped in 2003, but later revived in 2004 after India increased its contribution and overall costs were lowered.<ref>[http://www.space.com/spacenews/archive04/missionarch_022404.html India and France Resurrect, Redesign Megha-Tropiques Mission] {{webarchive|url=https://web.archive.org/web/20090405074928/http://www.space.com/spacenews/archive04/missionarch_022404.html }}, PETER B. de SELDING And K.S. JAYARAMAN. 24 February 2004</ref><ref>[http://www.isro.org/pressrelease/Nov12_2004.htm ISRO and French Space Agency, CNES, Sign MOU on Megha-Tropiques Satellite Mission] {{Webarchive|url=https://web.archive.org/web/20080517072526/http://www.isro.org/pressrelease/Nov12_2004.htm }} November 12, 2004</ref> With the progress made by [[GEWEX]] (Global Energy and Water Cycle Experiment), Megha-Tropiques was designed to understand tropical meteorological and climatic processes, by obtaining reliable statistics on the water and energy budget of the tropical atmosphere.<ref>{{cite web|url=http://www.gewex.org/gewex_overview.html |title=About GEWEX |publisher=Gewex.org |access-date=2010-12-05}}</ref> Megha-Tropiques complemented other data in regional monsoon projects such as MAHASRI and the completed GAME project.<ref>{{cite web |url=http://mahasri.cr.chiba-u.ac.jp/index_e.html |title=Monsoon Asian Hydro-Atmosphere Scientific Research and Prediction Initiative |publisher=Mahasri.cr.chiba-u.ac.jp |access-date=2010-12-05 |url-status=dead |archive-url=https://web.archive.org/web/20110722071310/http://mahasri.cr.chiba-u.ac.jp/index_e.html |archive-date=2011-07-22 }}</ref><ref>{{cite web|url=http://www.hyarc.nagoya-u.ac.jp/game/ |title=GEWEX Asian Monsoon Experiment |publisher=Hyarc.nagoya-u.ac.jp |access-date=2010-12-05}}</ref> Megha-Tropiques also sought to describe the evolution of major tropical weather systems. The focus was the repetitive measurement of the tropics.<ref>{{cite web|url=http://www.spacemart.com/reports/India_And_France_To_Launch_Weather_Satellite_Early_Next_Year_999.html |title=Launch Info |publisher=Spacemart.com |access-date=2010-12-05}}</ref>

==Design==
Megha-Tropiques instruments allowed simultaneous observation of three interrelated components of the atmospheric engine: water vapor, condensed water (clouds and precipitations), and radiative fluxes, facilitating the repetitive sampling of the inter-tropical zone over long periods of time. Its microwave radiometer, Multi-frequency Microwave Scanning Radiometer ([[Special Sensor Microwave/Imager|MADRAS]]), complemented the radiometers of the other elements of the [[Global Precipitation Measurement|Global Precipitation Measurement mission]].<ref name="eoportal">{{cite web |url=https://directory.eoportal.org/web/eoportal/satellite-missions/m/megha-tropiques |title=Megha-Tropiques (Meteorological LEO Observations in the Intertropical Zone) |work=eoPortal |publisher=[[ESA]] |access-date=8 April 2022}}</ref>

==Payload==
Instruments fulfill a critical role on earth observation satellites. On this mission, microwave instruments were essential.
* ''' Microwave Analysis and Detection of Rain and Atmospheric Structures (MADRAS)''' is a [[microwave]] imager, with conical scanning (incidence angle 56°), close from the SSM/I and TMI concepts. The main aim of the mission being the study of [[cloud]] systems, a frequency has been added (150 GHz) in order to study the high level [[ice cloud]]s associated with the convective systems, and to serve as a window channel relative to the sounding instrument at 183 GHz.
* '''Sounder for Probing Vertical Profiles of Humidity (SAPHIR)''' is a sounding instrument with 6 channels near the absorption band of [[water vapor]] at 183 GHz. These channels provide relatively narrow weighting functions from the surface to about {{cvt|10|km}}, allowing retrieving water vapor profiles in the cloud free [[troposphere]]. The scanning is cross-track, up to an incidence angle of 50°. The resolution at nadir is of {{cvt|10|km}}.
* '''Scanner for Radiation Budget (ScaRaB)''' is a scanning radiative budget instrument, which has already been launched twice on Russian satellites. The basic measurements of ScaRaB are the radiances in two wide channels, a solar channel (0.2 - 4 µm), and a total channel (0.2 - 200 µm), allowing to derive longwave radiances. The resolution at nadir will be {{cvt|40|km}} from an orbit at {{cvt|870|km}}. The procedures of calibration and processing of the data in order to derive fluxes from the original radiances have been set up and tested by [[CNES]] and LMD.
* '''Radio Occultation Sensor for Vertical Profiling of Temperature and Humidity (ROSA)''' procured from Italy for vertical profiling of temperature and humidity.<ref>{{cite journal|title=Space Observations and Monitoring of Climate Changes - Indian Initiatives |url=http://www.oosa.unvienna.org/pdf/pres/stsc2009/symp-03.pdf|access-date=November 12, 2022|journal=46th Session of the Scientific and Technical Subcommittee of United Nations Committee on the Peaceful Uses of Outer Space}}</ref>

==Launch==
The Megha-Tropiques satellite was successfully placed in an {{cvt|867|km}} orbit with an inclination of 20 degrees to the equator by the [[Indian Space Research Organisation]] through its Polar Satellite Launch Vehicle ([[PSLV|PSLV-C18]]) on October 12, 2011.<ref>{{cite web |url=http://www.isro.org/satellites/megha-tropiques.aspx |title=Welcome to ISRO :: Satellites :: Earth Observation Satellite :: Megha-Tropiques |access-date=2011-10-17 |url-status=dead |archive-url=https://web.archive.org/web/20111015142446/http://isro.org/satellites/Megha-Tropiques.aspx |archive-date=2011-10-15 }}</ref> The [[PSLV|PSLV-C18]] was launched at 11:00 am on October 12, 2011, from the first launch pad of the Satish Dhawan Space Centre (SHAR) located in [[Sriharikota]], [[Andhra Pradesh]]. The satellite was placed in orbit along with three micro satellites: the {{cvt|10.9|kg}} [[SRMSAT]] built by the SRM University, Chennai, the {{cvt|3|kg}} remote sensing satellite [[Jugnu (satellite)|Jugnu]] from the Indian Institute of Technology Kanpur(IIT Kanpur) and the {{cvt|28.7|kg}} [[VesselSat-1]] of [[Luxembourg]] to locate ships on high seas.<ref>{{Cite web|url=http://www.ndtv.com/article/india/india-launches-first-satellite-devoted-to-studying-monsoon-140409|title=ISRO launches Megha-Tropiques satellite to study monsoon}}</ref><ref>{{cite news| url=http://timesofindia.indiatimes.com/india/PSLV-C18-carrying-weather-satellite-launched/articleshow/10323961.cms | work=The Times Of India | title=PSLV-C18 carrying weather satellite launched - The Times of India}}</ref>

==End of Mission==
The original mission life was three years. The mission was extended by two years on 26 May 2015.<ref>{{Cite web |title=Mission Megha-Tropiques |url=https://megha-tropiques.cnes.fr/en/mission-megha-tropiques |access-date=2022-04-08 |website=Megha-tropiques |language=en}}</ref> The mission was further extended by four years on 7 October 2016.<ref>{{Cite web |title=France-India space cooperation - Four more years for emblematic Megha-Tropiques climate space mission |url=https://presse.cnes.fr/en/france-india-space-cooperation-four-more-years-emblematic-megha-tropiques-climate-space-mission |access-date=2022-04-08 |website=presse.cnes.fr |language=en}}</ref>

In April 2022, ISRO announced the end of mission for the satellite because of issues with the attitude control sub-system. Megha-Tropiques was located at an 870 km orbit, which was to be lowered to 300 km to prepare for the eventual disposal of the satellite.<ref>{{cite web |last=Kumar |first=Chethan |url=https://timesofindia.indiatimes.com/home/science/after-over-10-years-its-end-of-mission-for-indo-french-sat-megha-tropiques/articleshow/90711253.cms |title=After over 10 years, it's end of mission for Indo-French sat Megha-Tropiques |work=[[The Times of India]] |access-date=8 April 2022}}</ref>

Starting from August 2022, Megha-Tropiques' orbit was lowered through a series of maneuvers. On 7 March 2023, Megha-Tropiques was successfully deorbited after conducting two final de-boost burns.<ref name="isro-reentry">{{cite web |url=https://www.isro.gov.in/mt1-rentry-successful.html |title=MT1 Controlled Re-entry Successful and impacted on the Pacific Ocean |work=[[ISRO]] |access-date=8 March 2023}}</ref>

==References==
{{reflist}}

==External links==

* [https://web.archive.org/web/20120213145729/http://meghatropiques.ipsl.polytechnique.fr/ Megha-Tropiques Official Site]

{{Indian space programme}}
{{Indian spacecraft}}
{{Orbital launches in 2011}}

[[Category:Earth observation satellites of France]]
[[Category:Earth observation satellites of India]]
[[Category:Satellite meteorology]]
[[Category:Spacecraft launched in 2011]]
[[Category:2011 in India]]
[[Category:2011 in France]]
[[Category:Spacecraft decommissioned in 2022]]
[[Category:Spacecraft which reentered in 2023]]

Megha-Tropiques - Revision history

CleanupBot II at 11:07, 14 August 2023