The NISAR mission will help map crops and track their
development through the entire growing season. Using synthetic aperture radar,
the satellite will be able to observe both small plots of farmland and monitor
trends across broad regions, gathering data to in-form agricultural decision
making.
Adobe Stock/Greg Kelton
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.
NISAR will provide maps of croplands on a global
basis every two weeks. Observations will be uninterrupted by weather and
provide up-to-date information on the large-scale trends that affect
international food security. Credit: NASA/JPL-Caltech
“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.
Data gathered in 2017 by the European Sentinel-1 SAR
satellite program shows changes to croplands in the region southeast of
Florida’s Lake Okeechobee. Colors in the fields indicate various crops in
different parts of their growth and harvest cycles. NISAR will gather similar
data in L- and S-band radar frequencies.
ESA; processing and visualization by Earth Big Data
LLC
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.
A collaboration between NASA and the Indian Space
Research Organisation, NISAR will use synthetic aperture radar to offer
insights into change in Earth’s ecosystems, including its agricultural lands.
The spacecraft, depicted here in an artist’s concept, will launch from India.
NASA/JPL-Caltech
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: https://nisar.jpl.nasa.gov
By: Jet Propulsion Laboratory
Source: NASA-ISRO Mission Will Map Farmland From Planting to Harvest - NASA
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