Data from the NISAR satellite will be used to map crop growth, track plant health, and monitor soil moisture — offering detailed, timely information for decision making.
When it launches this year, the NISAR (NASA-ISRO Synthetic Aperture Radar) satellite will provide a powerful data stream that could help farmers in the U.S. and around the world. This new Earth mission by NASA and the Indian Space Research Organisation will help monitor the growth of crops from planting to harvest, generating crucial insights on how to time plantings, adjust irrigation schedules, and, ultimately, make the most of another precious resource: time.
Using synthetic aperture radar, NISAR will discern the physical characteristics of crops, as well as the moisture content of the plants and the soil they grow in. The mission will have the resolution to see small plots of farmland, but a potentially more meaningful benefit will come from its broad, frequent coverage of agricultural regions.
The satellite will image nearly all of Earth’s land twice every 12 days and will be able to resolve plots down to 30 feet (10 meters) wide. The cadence and resolution could allow users to zoom in to observe week-to-week changes on small farms or zoom out to monitor thousands of farms for broader trends. Such big-picture perspective will be useful for authorities managing crops or setting farm policy.
Tapping NISAR data, decision-makers could, for example, estimate when rice seedlings were planted across a region and track their height and blooming through the season while also monitoring the wetness of the plants and paddies over time. An unhealthy crop or drier paddies may signal the need to shift management strategies.
“It’s all about resource planning and optimizing, and timing is very important when it comes to crops: When is the best time to plant? When is the best time to irrigate? That is the whole game here,” said Narendra Das, a NISAR science team member and agricultural engineering researcher at Michigan State University in East Lansing.
Mapping Crops
NISAR is set to launch this year from ISRO’s Satish Dhawan Space Centre on India’s southeastern coast. Once in operation, it will produce about 80 terabytes of data products per day for researchers and users across numerous areas, including agriculture.
Satellites have been used for large-scale crop monitoring for decades. Because microwaves pass through clouds, radar can be more effective at observing crops during rainy seasons than other technologies such as thermal and optical imaging. The NISAR satellite will be the first radar satellite to employ two frequencies, L- and S-band, which will enable it to observe a broader range of surface features than a single instrument working at one frequency.
Microwaves from the mission’s radars will be able to penetrate the canopies of crops such as corn, rice, and wheat, then bounce off the plant stalks, soil, or water below, and then back to the sensor. This data will enable users to estimate the mass of the plant matter (biomass) that’s aboveground in an area. By interpreting the data over time and pairing it with optical imagery, users will be able to distinguish crop types based on growth patterns.
Additionally, NISAR’s radars will measure how the polarization, or vertical and horizontal orientation of signals, changes after they bounce back to the satellite from the surface. This will enable a technique called polarimetry that, when applied to the data, will help identify crops and estimate crop production with better accuracy.
“Another superpower of NISAR is that when its measurements are integrated with traditional satellite observations, especially vegetation health indexes, it will significantly enhance crop information,” added Brad Doorn, who oversees NASA’s water resources and agriculture research program.
The NISAR satellite’s high-resolution data on which crops are present and how well they are growing could feed into agricultural productivity forecasts.
“The government of India — or any government in the world — wants to know the crop acreage and the production estimates in a very precise way,” said Bimal Kumar Bhattacharya, the agricultural applications lead at ISRO’s Space Applications Centre in Ahmedabad. “The high-repeat time-series data of NISAR will be very, very helpful.”
Tracking Soil Moisture
The NISAR satellite can also help farmers gauge the water content in soil and vegetation. In general, wetter soils tend to return more signals and show up brighter in radar imagery than drier soils. There is a similar relationship with plant moisture.
These capabilities mean that NISAR can estimate the water content of crops over a growing season to help determine if they are water-stressed, and it can use signals that have scattered back from the ground to estimate soil moisture.
The soil moisture data could potentially inform agriculture and water managers about how croplands respond to heat waves or droughts, as well as how quickly they absorb water and then dry out following rain — information that could support irrigation planning.
“Resource managers thinking about food security and where resources need to go are going to be able to use this sort of data to have a holistic view of their whole region,” said Rowena Lohman, an Earth sciences researcher at Cornell University in Ithaca, New York, and soil moisture lead on the NISAR science team.
More About NISAR
The NISAR satellite is a joint collaboration between NASA and ISRO and marks the first time the two agencies have cooperated on flight hardware for an Earth-observing mission. Managed by Caltech, NASA’s Jet Propulsion Laboratory leads the U.S. component of the project and provided the L-band SAR. NASA JPL also provided the radar reflector antenna, the deployable boom, a high-rate communication subsystem for science data, GPS receivers, a solid-state recorder, and payload data subsystem. NASA’s Goddard Space Flight Center manages the Near Space Network, which will receive NISAR’s L-band data.
The ISRO Space Applications Centre is providing the mission’s S-band SAR. The U R Rao Satellite Centre provided the spacecraft bus. The launch vehicle is from Vikram Sarabhai Space Centre, launch services are through Satish Dhawan Space Centre, and satellite mission operations are by the ISRO Telemetry Tracking and Command Network. The National Remote Sensing Centre is responsible for S-band data reception, operational products generation, and dissemination.
To learn more about NISAR, visit:
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2025-035
