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{{Short description|Series of Indian radar imaging satellites}}
{{Use Indian English|date=October 2020}}
{{Infobox spacecraft class
| name            = RISAT<br />(Radar Imaging Satellite)
| image           = Render of Radar Imaging Satellite RISAT-1 in deployed configuration.png
| caption         = Render of Radar Imaging Satellite RISAT-1 in deployed configuration.
| image_size      = 290px

| manufacturer    = [[Astronomy:ISRO|ISRO]]
| country         = {{wipe|India}}
| operator        = [[Astronomy:ISRO|ISRO]]
| lifetime        =

| bus             = 
| applications    = [[Imaging radar|Earth imaging]] SAR

| orbit_reference = [[Astronomy:Geocentric orbit|Geocentric orbit]]
| orbits          = [[Astronomy:Sun-synchronous orbit|SSO]]

| status          = Operational
| launched        = 6
| operational     = 4
| failed          = 
| lost            = 1
| first           = [[Engineering:RISAT-2|RISAT-2]] (2009)
| last            = [[Engineering:RISAT-1A|RISAT-1A]] (2022)
| retired         =

| mass            = {{cvt|400|kg}}-{{cvt|2000|kg}}
| power           = Up to 2200 W
| batteries       = Solar
| equipment       = Synthetic Aperture Radar
}}

'''RISAT (Radar Imaging Satellite)'''  is a series of {{wipe|India}}n radar imaging [[Astronomy:Reconnaissance satellite|reconnaissance satellite]]s built by the [[Astronomy:ISRO|Indian Space Research Organization]] (ISRO). They provide all-weather surveillance using synthetic aperture radars (SAR).

The ''RISAT'' series are the first all-weather [[Astronomy:Earth observation satellite|Earth observation satellite]]s from ISRO. Previous Indian observation satellites relied primarily on optical and spectral sensors which were hampered by [[Earth:Cloud cover|cloud cover]].

After the 26 November 2008, 2008 Mumbai attacks, the launch plan was modified to launch [[Engineering:RISAT-2|RISAT-2]] before [[Engineering:RISAT-1|RISAT-1]], since the indigenous [[Astronomy:C band (IEEE)|C-band]] SAR to be used for RISAT-1 was not ready. RISAT-2 used an Israel Aerospace Industries (IAI) [[Astronomy:X-band|X-band]] SAR sensor similar to the one employed on [[Engineering:TecSAR|TecSAR]].

== Satellites ==
=== RISAT 2 ===
{{main|Engineering:RISAT-2}}
RISAT-2 was the last of the RISAT series to reach orbit.<ref name="ASM News">{{cite web|url=http://www.asmmag.com/news/risat-2-launched|title=Risat-2 Launched|publisher=ASM|access-date=2009-03-22|url-status=dead|archive-url=https://web.archive.org/web/20090424210905/http://www.asmmag.com/news/risat-2-launched|archive-date=2009-04-24}}</ref> It was launched successfully on 20 April 2009 at 0015 hours GMT by a PSLV rocket. The 300-kg satellite was built by ISRO using a X-band SAR manufactured by IAI.<ref name="CNN">{{cite news|url=http://edition.cnn.com/2009/WORLD/asiapcf/03/21/india.satellite/|title=India to launch Israel-backed satellite|publisher=CNN|access-date=2009-03-22 | date=2009-03-21}}</ref><ref>{{cite web |url=http://www.iai.co.il/ |title=Home |website=iai.co.il}}</ref><ref name="PTI">{{cite news|url=https://earsc.org/2009/03/23/india-set-to-launch-imaging-satellite-with-israeli-support/ |title=India set to launch imaging satellite with Israeli support |date=23 Mar 2009 |publisher=European Association of Remote Sensing Companies|access-date=2 Jan 2023 }}</ref>

This satellite was fast tracked in the aftermath of the 2008 Mumbai attacks.<ref name=ASM>{{cite web|url=http://www.asmmag.com/news/india-to-launch-risat|title=The difference between Risat-1 and Risat-2|publisher=ASM|access-date=2009-03-25|url-status=dead|archive-url=https://web.archive.org/web/20100912231400/http://www.asmmag.com/news/india-to-launch-risat|archive-date=2010-09-12}}</ref> The satellite will be used for border surveillance, to deter insurgent infiltration and for anti-terrorist operations.<ref name="timesofindia.indiatimes.com">{{cite news| url=http://timesofindia.indiatimes.com/articleshow/4374544.cms | work=The Times Of India | title=India to launch spy satellite on April 20 | date=2009-04-08}}</ref> It is likely to be placed under the Aerospace Command of the {{wipe|Indian Air Force}}.<ref>{{cite web |url=http://news.xinhuanet.com/english/2009-02/13/content_10815093.htm |title=Indian Air Force to have independent satellite by 2010 _English_Xinhua |access-date=2009-04-06 |url-status=dead |archive-url=https://web.archive.org/web/20090216113933/http://news.xinhuanet.com/english/2009-02/13/content_10815093.htm |archive-date=2009-02-16 }}</ref>

No details of the technical specifications of RISAT-2 have been published. However, it is likely to have a spatial resolution of about a metre or so. Ship detection algorithms for radar satellites of this class are well-known and available. The satellite also has applications in the area of disaster management and agriculture-related activities.<ref name="timesofindia.indiatimes.com"/><ref>{{cite web|title=RISAT-2: Spy in the Sky|url=https://www.sps-aviation.com/story/?id=279|publisher=SP's Aviation|access-date=April 29, 2023}}</ref>

=== RISAT 1 ===
{{main|Engineering:RISAT-1}}
RISAT-1 was an indigenously developed radar imaging satellite successfully launched by a PSLV-XL rocket on 26 April 2012 from Satish Dhawan Space Centre, Shriharikota. RISAT-1 was postponed in order to prioritize the building and launch of RISAT-2.<ref name=ASM/><ref name="ID">{{cite news|url=http://www.indodaily.com/reports/ISRO_New_Satellite_Could_See_Through_Even_Cloudy_Sky_999.html|title=ISRO's New Satellite Could See Through Even Cloudy Sky|date=7 November 2008|publisher=Indo Daily|access-date=2009-03-21|url-status=dead|archive-url=https://web.archive.org/web/20110520224119/http://www.indodaily.com/reports/ISRO_New_Satellite_Could_See_Through_Even_Cloudy_Sky_999.html|archive-date=20 May 2011}}</ref><ref>[http://www.spacemart.com/reports/RISAT_Is_A_Home_Grown_Satellite_999.html Launch Info] {{webarchive|url=https://web.archive.org/web/20090522181615/http://www.spacemart.com/reports/RISAT_Is_A_Home_Grown_Satellite_999.html |date=2009-05-22 }}</ref><ref name="ISRO">{{cite web|url=http://www.isro.gov.in/rep2005/EOS.htm |title=Earth Observation System |publisher=ISRO |access-date=2009-03-21 |url-status=dead |archive-url=https://web.archive.org/web/20081010150300/http://www.isro.gov.in/rep2005/EOS.htm |archive-date=10 October 2008 }}</ref>

The features of RISAT-1 include: 
* 160 x 4 Mbit/s data handling system
* 50 Newton-meter-second reaction wheels
* SAR antenna deployment mechanism
* Phased array antenna with dual polarisation

=== RISAT 2B ===
{{main|Engineering:RISAT-2B}}
RISAT-2B is an indigenously developed Synthetic Aperture Radar (SAR) imaging satellite operating in X Band with 3.6 m radial rib antenna.<ref>{{Cite web|url=https://www.isro.gov.in/update/22-may-2019/risat-2b-radial-rib-antenna|title=RISAT-2B: Radial Rib Antenna - ISRO|website=www.isro.gov.in|access-date=2019-07-04|archive-date=29 May 2019|archive-url=https://web.archive.org/web/20190529104039/https://www.isro.gov.in/update/22-may-2019/risat-2b-radial-rib-antenna|url-status=dead}}</ref> It was launched by PSLV C46 (Core Alone) on  22 May 2019 at 0000 (UTC) from First Launch Pad of SDSC (SHAR).<ref>{{Cite web|url=https://www.isro.gov.in/update/22-may-2019/pslv-c46-successfully-launches-risat-2b|title=PSLV-C46 successfully launches RISAT-2B - ISRO|website=www.isro.gov.in|access-date=2019-07-04|archive-date=28 May 2019|archive-url=https://web.archive.org/web/20190528045558/https://www.isro.gov.in/update/22-may-2019/pslv-c46-successfully-launches-risat-2b|url-status=dead}}</ref>

The satellite has the capability to operate in different modes including Very High Resolution RADAR imaging modes of 1m × 0.5m resolution and 0.5m × 0.3m resolution. RISAT-2B is placed in an inclined orbit for better revisit rates over area of interest. Being Radar Imaging satellite, it can image during day / night / all weather conditions. The Satellite will be utilized for high resolution spot imaging of locations of interest.<ref>{{Cite web|url=http://164.100.158.235/question/annex/249/Au1531.pdf|title=Rajya Sabha Unstarred Question No. 1531 : Earth Observation satellite RISAT-2B|date=4 July 2019|access-date=4 July 2019}}</ref><ref>{{Cite web|url=http://pib.nic.in/newsite/PrintRelease.aspx?relid=191250|title=Earth Observation Satellite RISAT-2B|website=pib.nic.in|access-date=2019-07-04}}</ref>

* Mass: 615&nbsp;kg<ref name=":0">{{Cite web|url=https://www.isro.gov.in/sites/default/files/flipping_book/pslv-c46_risat2b_launch_kit/PSLV-C46_RISAT2B_launch_kit/files/assets/common/downloads/PSLV-C46%20RISAT2B%20launch%20kit.pdf|title=PSLV-C46/RISAT-2B press kit|date=17 May 2019|access-date=4 July 2019|archive-date=14 December 2020|archive-url=https://web.archive.org/web/20201214225900/https://www.isro.gov.in/sites/default/files/flipping_book/pslv-c46_risat2b_launch_kit/PSLV-C46_RISAT2B_launch_kit/files/assets/common/downloads/PSLV-C46%20RISAT2B%20launch%20kit.pdf|url-status=dead}}</ref>
* Orbit: 557&nbsp;km (circular) at inclination of 37°<ref name=":0" />
* Mission life: 5 years<ref name=":0" />

=== RISAT 2BR1 ===
{{main|Engineering:RISAT-2BR1}}
RISAT-2BR1 is an Indian radar reconnaissance satellite that is part of India's RISAT programme and the fourth satellite in the series. It is built by [[Astronomy:Indian Space Research Organisation|Indian Space Research Organisation]] (ISRO). It was launched on 11 December 2019 at 3:25 PM IST on board PSLV rocket from Satish Dhawan Space Centre.<ref>{{Cite web|url=https://www-news18-com.cdn.ampproject.org/v/s/www.news18.com/amp/news/india/with-few-hours-left-for-launch-of-isros-risat-2br1-heres-all-you-need-to-know-about-the-spy-satellite-2419867.html?usqp=mq331AQCKAE=&amp_js_v=0.1|title=ISRO's RISAT-2BR1, 9 Other Foreign Satellites Blast Off from Sriharikota|website=www-news18-com.cdn.ampproject.org|access-date=2019-12-11}}</ref>

The satellite has resolution of 0.35 meters by which two objects separated by distance of 0.35 metres can be distinctly identified. The mission duration is planned to be 5 years. It is the 50th launch of [[Engineering:Polar Satellite Launch Vehicle|Polar Satellite Launch Vehicle]] and 75th launch from [[Astronomy:Satish Dhawan Space Centre|Satish Dhawan Space Centre]].<ref name="Isro to launch">{{Cite web|url=https://timesofindia.indiatimes.com/india/isro-to-launch-another-eye-in-the-sky-risat-2br1-on-dec-11-will-help-boost-border-surveillance/articleshow/72340281.cms|title=Isro to launch another 'eye in the sky' Risat-2BR1 on December 11, will help boost border surveillance|date=3 December 2019|first=Surendra|last=Singh|website=The Times of India|language=en|access-date=2019-12-11}}</ref><ref>{{Cite news|url=https://www.business-standard.com/article/current-affairs/isro-to-launch-border-surveillance-satellite-risat-2br1-on-dec-11-119120301040_1.html|title=ISRO to launch border surveillance satellite Risat-2BR1 on Dec 11|last=IANS|date=2019-12-03|work=Business Standard India|access-date=2019-12-11}}</ref>
* Mass: 628&nbsp;kg<ref name="Isro to launch"/>
* Orbit: 560&nbsp;km<ref name="Isro to launch"/>
* Mission life : 5 years<ref name="Isro to launch"/>

== List of RISAT Satellite ==
{| class = "wikitable"
! Designation
! Resolution (in meters)
! COSPAR ID
! [[Engineering:Satellite Catalog Number|NORAD ID]]
! Power
! Launch date, Time (UTC)
! Launch mass
! Launch vehicle
! Launch site
! Remarks
|-
| [[Engineering:RISAT-1|RISAT-1]]
| 1
| 2012-017A
| 38248
| 2200 watts <ref>{{cite web|last1=RISAT-1|first1=ISRO|title=RISAT-1|url=https://www.isro.gov.in/Spacecraft/risat-1|website=isro.gov.in|publisher=ISRO|access-date=28 October 2020|archive-date=16 January 2021|archive-url=https://web.archive.org/web/20210116221615/https://www.isro.gov.in/Spacecraft/risat-1|url-status=dead}}</ref>
| 26 April 2012, 00:17
| {{cvt|1858|kg}}
| PSLV-XL -C19
| [[Astronomy:Satish Dhawan Space Centre|SDSC]], [[Astronomy:Satish Dhawan Space Centre First Launch Pad|FLP]]
| Equipped with indigenous SAR.
|-
| [[Engineering:RISAT-1A|EOS-4/RISAT-1A]]
| 
| 2022-013A
| 51656
| 2280 watts<ref>{{Cite web|title=PSLV-C52/EOS-04 Brochure - ISRO|url=https://www.isro.gov.in/pslv-c52-eos-04-mission/pslv-c52-eos-04-brochure|access-date=2022-02-10|website=www.isro.gov.in|archive-date=9 February 2022|archive-url=https://web.archive.org/web/20220209140030/https://www.isro.gov.in/pslv-c52-eos-04-mission/pslv-c52-eos-04-brochure|url-status=dead}}</ref>
| 14 February 2022, 00:29<ref name="PSLV-C52/EOS-04 Mission - ISRO">{{Cite web|title=PSLV-C52/EOS-04 Mission - ISRO|url=https://www.isro.gov.in/launcher/pslv-c52-eos-04-mission|access-date=2022-02-10|website=www.isro.gov.in|archive-date=9 February 2022|archive-url=https://web.archive.org/web/20220209012447/https://www.isro.gov.in/launcher/pslv-c52-eos-04-mission|url-status=dead}}</ref>
| {{cvt|1710|kg}}<ref name="PSLV-C52/EOS-04 Mission - ISRO"/>
| PSLV-XL C52
| [[Astronomy:Satish Dhawan Space Centre|SDSC]], [[Astronomy:Satish Dhawan Space Centre First Launch Pad|FLP]]
|
|-
| RISAT-1B
| 
| 
| 
| 
| 2024 
| 
| PSLV-XL
| [[Astronomy:Satish Dhawan Space Centre|SDSC]]
| 
|-
| [[Engineering:RISAT-2|RISAT-2]]
| Unknown
| 2009-019A
| 34807
| 
| 20 April 2009, 01:15
| {{cvt|300|kg}}
| PSLV-CA -C12
| [[Astronomy:Satish Dhawan Space Centre|SDSC]], [[Astronomy:Satish Dhawan Space Centre Second Launch Pad|SLP]]
| Equipped with Israeli SAR similar to that in [[Engineering:TecSAR|TecSAR]].
|-
| RISAT-2A
| 
| 
| 
| 
| 2024-25
| 
| PSLV-XL
| [[Astronomy:Satish Dhawan Space Centre|SDSC]]
| 
|-
| [[Engineering:RISAT-2B|RISAT-2B]]
| 0.5 x 0.3
| 2019-028A
| 44233
| 
| 22 May 2019, 00:00
| {{cvt|615|kg}}
| PSLV-CA -C46
| [[Astronomy:Satish Dhawan Space Centre|SDSC]], [[Astronomy:Satish Dhawan Space Centre First Launch Pad|FLP]]
| 
|-
| [[Engineering:RISAT-2BR1|RISAT-2BR1]]
| 0.35
| 2019-089F
| 44857
| 
| 11 December 2019, 09:55 
| {{cvt|628|kg}}
| PSLV-QL -C48
| [[Astronomy:Satish Dhawan Space Centre|SDSC]], [[Astronomy:Satish Dhawan Space Centre First Launch Pad|FLP]]
| 
|-
| [[Astronomy:EOS-01|EOS-01]]/RISAT-2BR2
| 
| 2020-081A
| 46905
| 
| 7 November 2020, 09:41
| {{cvt|630|kg}}<ref>{{cite news|url=https://spaceflightnow.com/2020/11/07/indian-pslv-deploys-10-satellites-in-first-launch-since-start-of-pandemic/|title=Indian PSLV deploys 10 satellites in first launch since start of pandemic|publisher=Spaceflight Now|date=7 November 2020|access-date=7 November 2020}}</ref>
| PSLV-DL -C49
| [[Astronomy:Satish Dhawan Space Centre|SDSC]], [[Astronomy:Satish Dhawan Space Centre First Launch Pad|FLP]]
| 
|-
|}

== See also ==
* [[Engineering:Cartosat|Cartosat]]
* [[Astronomy:Indian Space Research Organisation|Indian Space Research Organisation]]
* NISAR

== References ==
{{reflist}}

{{Indian space programme}}

{{DEFAULTSORT:Risat}}
[[Category:Space programme of India]]
[[Category:Synthetic aperture radar satellites]]
[[Category:Satellite series]]

{{Sourceattribution|RISAT}}