NISAR observation satellite

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About NISAR-

• The word ‘NISAR’ finds its origin in NASA-ISRO-SAR. 
• It is an SUV-sized satellite that is dedicatedly developed by the space agencies of the U.S and India for studying hazards and global environmental change.
• India and the US had agreed upon this mission during then-President Barack Obama’s visit to India in 2015. 
• The major scientific objectives of the NISAR mission are to improve understanding of the impact of climate change on Earth’s dynamic ecosystem, land, and coastal processes, land deformations, and cryosphere.
• It will observe Earth’s land with 12-day regularity on ascending and descending passes, sampling Earth on average every 6 days for a baseline 3-year mission.
• The mission that is equipped with the largest reflector antenna ever launched by NASA, will measure Earth’s changing ecosystems and dynamic surfaces, spotting warning signs of imminent volcanic eruptions on one hand, and ice masses on the other, providing information about biomass, natural hazards, sea-level rise,earthquakes, landslides, tsunamis and aid in monitoring groundwater supplies.
• NISAR’s global and rapid coverage will provide unprecedented opportunities for disaster response, providing data to assist in mitigating and assessing damage, with observations before and after disasters in short time frames. 
• As far as utility is concerned, ISRO has identified few areas where NISAR’s findings would prove to be beneficial. These are – Agricultural monitoring and characterization, landslide studies, Himalayan glacier studies, soil moisture, coastal processes, coastal winds, among others that are crucial for India.
• NISAR will be the first satellite mission to use two different radar frequencies (L-band and S-band) to measure changes in our planet’s surface less than a centimetre across.
• Apart from S-band radar, ISRO is providing the spacecraft bus and the launch vehicle. 

What is SAR?

• SAR stands for ‘Synthetic Aperture Radar’ technique, responsible for producing high-resolution images from a resolution-limited radar system that NASA has used to measure changes in Earth’s surface. 
• Because of the utter precision, the radar can penetrate clouds and darkness, which means that it is capable of collecting data in any weather and at any time in the day and in the night.
• The NISAR spacecraft accommodates two different, fully capable synthetic aperture radar (SAR) frequencies namely – L-band and S-band. 
• The 24 cm wavelength L-band Synthetic Aperture Radar (L-SAR) is by NASA, while a 10 cm wavelength S-band (S-SAR) is provided by ISRO. 
• The SAR will measure the changes in our planet’s surface less than a centimeter across. In this way, SAR beats the resolution limits of what can physically be put in space to provide images.

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