View source for Engineering:RISAT-1

{{Short description|Indian Earth observation satellite}}
{{Infobox spaceflight
| name              = RISAT-1
| names_list        = Radar Imaging Satellite-1
| image             = Render_of_Radar_Imaging_Satellite_RISAT-1_in_deployed_configuration.png
| image_caption     = Render of RISAT-1 satellite
| image_size        = 300px

| mission_type      = [[Astronomy:Earth observation satellite|Earth observation]]<br/>[[Imaging radar|Radar imaging satellite]]
| operator          = [[Astronomy:Indian Space Research Organisation|ISRO]]
| COSPAR_ID         = 2012-017A
| SATCAT            = 38248
| website           = https://www.isro.gov.in/
| mission_duration  = 5 years (planned)<br/>4 years (achieved)
 
| spacecraft        = 
| spacecraft_type   = 
| spacecraft_bus    = [[Engineering:RISAT|RISAT]]
| manufacturer      = [[Astronomy:Indian Space Research Organisation|Indian Space Research Organisation]]
| launch_mass       = {{cvt|1858|kg}} <ref name=hindu-grandsuccess>{{cite news|url=http://www.thehindu.com/news/national/article3355368.ece|title=RISAT-1 satellite launch a "grand success"|newspaper=The Hindu |date=26 April 2012}}</ref>
| dry_mass          = 
| dimensions        = 
| power             = 2.2 [[Watt|kW]]

| launch_date       = 26 April 2012, 00:17 [[Physics:Coordinated Universal Time|UTC]]
| launch_rocket     = [[Engineering:Polar Satellite Launch Vehicle|Polar Satellite Launch Vehicle-XL]], PSLV-C19
| launch_site       = [[Astronomy:Satish Dhawan Space Centre|Satish Dhawan Space Centre]], [[Astronomy:Satish Dhawan Space Centre|First Launch Pad (FLP)]]
| launch_contractor = [[Astronomy:Indian Space Research Organisation|Indian Space Research Organisation]]

| entered_service   = 19 October 2012 <ref name="ESA">{{cite web|url=https://directory.eoportal.org/web/eoportal/satellite-missions/r/risat-1|title=RISAT-1 (Radar Imaging Satellite-1) - Status Mission |publisher=ESA Earth Observation Portal|date=9 May 2021|access-date=10 May 2021}}</ref>
| disposal_type     = 
| deactivated       = 31 March 2017 <ref name="DC"/><ref name="LS_reply"/>
| last_contact      = 30 September 2016 <ref name="ESA"/>

| orbit_reference   = [[Astronomy:Geocentric orbit|Geocentric orbit]]
| orbit_regime      = [[Astronomy:Sun-synchronous orbit|Sun-synchronous orbit]]
| orbit_periapsis   = {{cvt|539|km}}
| orbit_apoapsis    = {{cvt|543|km}}
| orbit_inclination = 97.55°
| orbit_period      = 95.49 minutes
| orbit_mean_motion = 14
| apsis             = gee

| instruments       = [[Engineering:Synthetic-aperture radar|Synthetic-aperture radar]] (C-band) (SAR-C)

| programme         = [[Astronomy:Earth observation satellite|Earth observation satellites series]]
| previous_mission  = Resourcesat-2
| next_mission      = [[Engineering:SARAL|SARAL]]
}}

'''Radar Imaging Satellite 1''' or '''RISAT-1''', was an Indian [[Earth:Remote sensing|remote sensing]] [[Astronomy:Satellite|satellite]] built and operated by the [[Astronomy:Indian Space Research Organisation|Indian Space Research Organisation]] (ISRO). The second [[Engineering:RISAT|RISAT]] satellite to be launched, it used a [[Astronomy:C band (IEEE)|C-band]] 5.35 [[Hertz|GHz]] [[Engineering:Synthetic-aperture radar|synthetic-aperture radar]] (SAR) for [[Astronomy:Earth observation satellite|Earth observation]].<ref name=hindu-risat1radar>{{cite news |url=http://www.thehindu.com/sci-tech/technology/article3350204.ece|title=RISAT-1's radar can see through clouds and work in darkness|newspaper=The Hindu|date=25 April 2012|location=Chennai, India|first=N. Gopal|last=Raj}}</ref>

The launch of RISAT-1 came several years after that of [[Engineering:RISAT-2|RISAT-2]], which carried an Israeli-built [[Physics:X band|X-band]] radar. The RISAT-2 mission was prioritised over RISAT-1 following the 2008 Mumbai attacks, resulting in RISAT-1 being delayed by several years.<ref>{{cite web|url=http://www.asianscientist.com/topnews/isro-launches-risat-1-radar-sensing-satellite-2012/|title=ISRO Launches India's First Radar Imaging Satellite, RISAT-1|publisher=Asian Scientist|first=Srinivas|last=Laxman|date=26 April 2012|access-date=26 April 2012}}</ref><ref name="ASM">{{cite web|url=http://www.asmmag.com/news/india-to-launch-risat|title=India to Launch RISAT-2|publisher=ASM|archiveurl=https://web.archive.org/web/20100912231400/http://www.asmmag.com/news/india-to-launch-risat|archive-date=12 September 2010|access-date=25 March 2009}}</ref><ref name="ID">{{cite news|url=http://www.indodaily.com/reports/ISRO_New_Satellite_Could_See_Through_Even_Cloudy_Sky_999.html|archive-url=https://archive.today/20110520224119/http://www.indodaily.com/reports/ISRO_New_Satellite_Could_See_Through_Even_Cloudy_Sky_999.html|url-status=dead|archive-date=20 May 2011|title=ISRO's New Satellite Could See Through Even Cloudy Sky|date=7 November 2008|publisher=Indo Daily|access-date=21 March 2009}}</ref>

== Satellite description ==
RISAT-1 had a mass at liftoff of {{cvt|1858|kg}}, making it the heaviest Earth observation satellite to be launched by India, and the heaviest satellite to be launched using a [[Engineering:Polar Satellite Launch Vehicle|Polar Satellite Launch Vehicle]]. It had the capability to take images of [[Astronomy:Earth|Earth]] during day and night, as well as in cloudy conditions.

The satellite is equipped with a 160 × 4&nbsp;Mbit/s data handling system, 50 [[Newton (unit)|Newton-metre-second]] reaction wheels, and a phased array antenna with dual polarisation.<ref>{{cite news|url=http://pibmumbai.gov.in/scripts/detail.asp?releaseId=E2012PR3130|title=The importance of RISAT-1|access-date=26 February 2013|newspaper=Press Information Bureau, Mumbai|date=26 April 2012}}</ref>

The mission has an approximate cost of {{INRConvert|4.90|b}};the spacecraft itself cost {{INRConvert|3.79|b}} to develop, and a further {{INRConvert|1.11|b}} to launch.<!--where are operational costs?--><ref name=toi-successfullaunch>{{cite news|url=http://timesofindia.indiatimes.com/india/India-successfully-launches-first-microwave-radar-imaging-satellite-RISAT--I/articleshow/12877123.cms|title=India successfully launches first microwave radar imaging satellite RISAT–1|newspaper=The Times of India|date=26 April 2012}}</ref> The satellite had a design life of five years.

The satellite was used for natural resources management, primarily agriculture planning and forestry surveys, as well as to predict and prevent [[Earth:Flood|flood]]ing. It was used for monitoring [[Earth:Paddy field|paddy]] plantations and yields in the kharif season and to assist India's food security planning. Pictures from RISAT-1 was used to estimate the number of hectares being farmed in India, to assess crop health and predict total yield. It was also used to identify wreckage from aircraft that crashed in forested areas.<ref name=hindu-grandsuccess/> RISAT-1 was not designed as a [[Astronomy:Reconnaissance satellite|surveillance satellite]], given its reliance on the [[Astronomy:C band (IEEE)|C-band]].<ref name=toi-successfullaunch/>

== Instrument ==
Its synthetic-aperture radar (SAR-C) has a resolution of 3 m to 50 m. It also supports a spotlight mode for prolonged focus on a given geographical area at a resolution of 1 m.<ref name=hindu-risat1radar/> Most of the design and the installation of basic instrument subsystems for the satellite was conducted in 2010.<ref name="ISRO">{{cite web|url=http://www.isro.gov.in/rep2005/EOS.htm|title=Earth Observation System |publisher=ISRO|access-date=21 March 2009|archive-url=https://web.archive.org/web/20081010150300/http://www.isro.gov.in/rep2005/EOS.htm|archive-date=10 October 2008}}</ref>

== Mission history ==
=== Launch ===
RISAT-1 was launched at 00:17 [[Physics:Coordinated Universal Time|UTC]] (05:47 IST) on 26 April 2012 by a [[Engineering:Polar Satellite Launch Vehicle|Polar Satellite Launch Vehicle]], flight number C19, flying in the XL configuration with extended length solid strap-on boosters. The launch, which was the third flight of the PSLV-XL configuration, took place from the [[Astronomy:Satish Dhawan Space Centre|First Launch Pad]] of the [[Astronomy:Satish Dhawan Space Centre|Satish Dhawan Space Centre]] in [[Place:Sriharikota|Sriharikota]], Andhra Pradesh. The launch marked the twenty-first flight of the PSLV, and its nineteenth successful launch.<ref>{{cite news |url=http://www.thehindu.com/news/national/article3355368.ece|newspaper=The Hindu|location=Chennai, India|first=M. Dinesh|last=Varma|title=PSLV-C19 puts RISAT-1 in orbit|date=26 April 2012}}</ref>

After launch RISAT-1 was placed in 470 x 480&nbsp;km orbit with near 97° [[Astronomy:Orbital inclination|inclination]]. In next two days, RISAT-1 raised its orbital altitude using on-board propulsion to place itself into its operational [[Astronomy:Sun-synchronous orbit|Sun-synchronous orbit]] of 536&nbsp;km with 06:00 Local Time of Equator Crossing.<ref>{{cite web|url=https://www.isac.gov.in/earth-observation/html/risat-1.jsp|title=RISAT-1|website=isac.gov.in |access-date=2018-02-22}}</ref><ref>{{cite web|url=https://www.isro.gov.in/update/28-apr-2012/radar-imaging-satellite-risat-1-successfully-placed-its-final-orbit|title=Radar Imaging Satellite (RISAT-1) successfully placed in its final orbit|publisher=ISRO|website=isro.gov.in|access-date=2018-02-22}}</ref> The satellite began its normal operations with a repetitive cycle of 25 days.

=== Incidents ===
On 30 September 2016, [[Social:Joint Space Operations Center|Joint Space Operations Center]] identified a debris generating event near RISAT-1.<ref>{{cite web|url=https://twitter.com/JointSpaceOps/status/783812350860140544|title=Debris-causing event ID'd near RISAT-1 (#38248) on 30 September 2016}}</ref><ref>{{cite web|url=https://orbitaldebris.jsc.nasa.gov/Quarterly-News/pdfs/ODQNv20i4.pdf|title=NASA Orbital Debris Quarterly News, Volume 20, Issue 4, October 2016}} {{PD-notice}}</ref> The event created 16 pieces out of which 15 decayed and one was catalogued on 6 October 2016 under NORAD ID: 41797 and COSPAR ID: 2012-017C and decayed on 12 October 2016. Cause of this event was not officially declared but could be related to power system of satellite.<ref>{{Cite news |last=Krishnan |first=Raghu |date=2018-05-09 |title=It will take 3 years for industry to absorb satellite tech: K Sivan, ISRO chairman |work=The Economic Times |url=https://economictimes.indiatimes.com/news/science/it-will-take-3-years-for-industry-to-absorb-satellite-tech-k-sivan-isro-chairman/articleshow/64088256.cms |access-date=2023-05-07 |issn=0013-0389 |quote=In GSAT-6A, there could be a power issue. A spark could have led to a short circuit. In the last three satellites — GSAT-6, RISAT and GSAT-6A — we have shifted to a higher-powered satellite bus. We saw there were similar problems in RISAT after it completed its life.}}</ref> A month later on 3 November 2016, RISAT-1 data was declared unavailable on ESA's Copernicus Space Component Data Access portal due to satellite outage. Satellite was experiencing anomalies but ISRO denied they were related to fragmentation event.<ref name="DC">{{cite news|url=http://www.deccanchronicle.com/science/science/280317/risat-1-satellite-is-functioning-normally-says-isro.html|title=Risat-1 satellite is functioning normally, says ISRO}}</ref><ref>{{cite web|url=https://spacedata.copernicus.eu/web/cscda/news/archive/-/asset_publisher/MUXrdlTX10kW/content/risat-1-unavailability|title=RISAT-1 unavailability|publisher=ESA}}</ref>

=== End of mission ===
On 26 July 2017, Department of Space released names of its operational satellites in a reply to a Parliamentary query and RISAT-1 was not included in the list.<ref name="LS_reply">{{cite web |url=http://164.100.47.194/Loksabha/Questions/QResult15.aspx?qref=54824&lsno=16|title=Details of satellites being operated by the country at present|last1=MORESHWAR PATIL|first1=KAPIL|last2=PATIL DANVE |first2=RAOSAHEB|date=26 July 2017|access-date=22 February 2018|last3=Singh|first3=Jitendra}}</ref><ref>{{cite web|url=http://164.100.47.190/loksabhaquestions/annex/12/AU1824.pdf|title=Details of satellites being operated by the country|date=26 July 2017|access-date=22 February 2018}}</ref> Later in Annual Report 2017-18 of Department of Space, RISAT-1 was declared non-operational.<ref>{{cite web |url=https://www.isro.gov.in/sites/default/files/article-files/node/9805/annualreport2017-18.pdf|title=Annual Report Department of Space 2017-18|website=isro.gov.in|publisher=Department of Space, Government of India|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|access-date=22 February 2018|quote=Anomalies have been observed towards the end of 5 years mission life and satellite is no more operational.}}</ref>

== References ==
{{Reflist}}

{{Indian spacecraft}}

[[Category:Space synthetic aperture radar]]

{{Sourceattribution|RISAT-1}}