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RISAT (Radar Imaging Satellite) (Hindi: रडार इमेजिंग सेटेलाइट) is a series of Indian radar imaging reconnaissance satellites built by ISRO. They provide all-weather surveillance using synthetic aperture radars (SAR).

The RISAT series are the first all-weather earth observation satellites from ISRO. Previous Indian observation satellites relied primarily on optical and spectral sensors which were hampered by cloud cover.

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

RISAT 2Edit

RISAT-2 was the first of the RISAT series to reach orbit.[1] It was launched successfully on April 20, 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.[2][3][4]

This satellite was fast tracked in the aftermath of the 2008 Mumbai attacks.[5] The satellite will be used for border surveillance, to deter insurgent infiltration and for anti-terrorist operations.[6] It is likely to be placed under the Aerospace Command of the Indian Air Force.[7]

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.[6]

RISAT 1Edit

RISAT-1 is an indigenously developed radar imaging satellite successfully launched by a PSLV-XL rocket on April 26, 2012 from Satish Dhawan Space Centre, Shriharikota. RISAT-1 was postponed in order to prioritize the building and launch of RISAT-2.[5][8][9][10]

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 2BEdit

RISAT-2B is an indigenously developed Synthetic Aperture Radar (SAR) imaging satellite operating in X Band with 3.6 m radial rib antenna.[11] It was launched by PSLV C46 (Core Alone) on 22 May 2019 at 0000 (UTC) from First Launch Pad of SDSC (SHAR).[12]

The highly agile satellite can 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.[13][14]

  • Mass: 615 kg[15]
  • Orbit: 557 km (circular) at inclination of 37°[15]
  • Mission life: 5 years[15]

ReferencesEdit

  1. ^ "Risat-2 Launched". ASM. Archived from the original on 2009-04-24. Retrieved 2009-03-22.
  2. ^ "India to launch Israel-backed satellite". CNN. 2009-03-21. Retrieved 2009-03-22.
  3. ^ http://www.iai.co.il
  4. ^ "India set to launch imaging satellite with Israeli support". PTI. 20 Mar 2009. Retrieved 2009-03-22.[dead link]
  5. ^ a b "The difference between Risat-1 and Risat-2". ASM. Archived from the original on 2010-09-12. Retrieved 2009-03-25.
  6. ^ a b "India to launch spy satellite on April 20". The Times Of India. 2009-04-08.
  7. ^ "Archived copy". Archived from the original on 2009-02-16. Retrieved 2009-04-06.CS1 maint: archived copy as title (link)
  8. ^ "ISRO's New Satellite Could See Through Even Cloudy Sky". Indo Daily. November 7, 2008. Archived from the original on May 20, 2011. Retrieved 2009-03-21.
  9. ^ Launch Info Archived 2009-05-22 at the Wayback Machine
  10. ^ "Earth Observation System". ISRO. Archived from the original on October 10, 2008. Retrieved 2009-03-21.
  11. ^ "RISAT-2B: Radial Rib Antenna - ISRO". www.isro.gov.in. Retrieved 2019-07-04.
  12. ^ "PSLV-C46 successfully launches RISAT-2B - ISRO". www.isro.gov.in. Retrieved 2019-07-04.
  13. ^ "Rajya Sabha Unstarred Question No. 1531 : Earth Observation satellite RISAT-2B" (PDF). 4 July 2019. Retrieved 4 July 2019.
  14. ^ "Earth Observation Satellite RISAT-2B". pib.nic.in. Retrieved 2019-07-04.
  15. ^ a b c "PSLV-C46/RISAT-2B press kit" (PDF). 17 May 2019. Retrieved 4 July 2019.