Snapshot from NISAR gives first glimpse into the satellite's capabilities

New Delhi: The first images from the joint NASA-ISRO satellite show a snapshot of the American landscape ranging from narrow waterways, islets dotting the fringes of an island, forests and wetlands, and large swathes of farms.

The first pictures from the NASA-ISRO Synthetic Aperture Radar (NISAR) satellite, billed as the most expensive satellite ever built, were released by NASA earlier this week.

A photograph of Mount Desert Island on the Maine coast, captured on August 21, shows narrow waterways cutting across the island, as well as the islets dotting the waters around it.

On August 23, the L-band SAR captured data of a portion of northeastern North Dakota straddling Grand Forks and Walsh counties.

The image shows forests and wetlands on the banks of the Forest River passing through the centre of the frame from west to east and farmland to the north and south.

The dark agricultural plots show fallow fields, while the lighter colours represent the presence of pasture or crops, such as soybean and corn.

Circular patterns indicate the use of centre-pivot irrigation, a statement from NASA said.

The images demonstrate how the L-band SAR can discern what type of land cover --“ low-lying vegetation, trees, and human structures -- is present in each area.

This capability is vital both for monitoring the gain and loss of forest and wetland ecosystems, and for tracking the progress of crops through growing seasons around the world.

"These initial images are just a preview of the hard-hitting science that NISAR will produce,“data and insights that will enable scientists to study Earth's changing land and ice surfaces in unprecedented detail while equipping decision-makers to respond to natural disasters and other challenges," said Nicky Fox, associate administrator, Science Mission Directorate at NASA Headquarters in Washington.

The NISAR satellite was launched from ISRO's Satish Dhawan Space Centre at Sriharikota, Andhra Pradesh on July 30.

The images are also a testament to the years of hard work of hundreds of scientists and engineers from both sides of the world to build an observatory with the most advanced radar system ever launched by NASA and ISRO, Fox said.

The L-band system uses a 10-inch (25-centimetre) wavelength that enables its signal to penetrate forest canopies and measure soil moisture and motion of ice surfaces and land down to fractions of an inch, which is a key measurement in understanding how the land surface moves before, during, and after earthquakes, volcanic eruptions, and landslides.

The preliminary L-band images are an example of what the mission team will be able to produce when the science phase begins in November.

The satellite was raised into its operational 747-kilometre orbit in mid-September.

The NISAR mission also includes an S-band radar, provided by ISRO's Space Applications Centre, that uses a 4-inch (10-centimetre) microwave signal that is more sensitive to small vegetation, making it effective at monitoring certain types of agriculture and grassland ecosystems.

The spacecraft is the first to carry both L- and S-band radars. The satellite will monitor Earth's land and ice surfaces twice every 12 days, collecting data using the spacecraft's drum-shaped antenna reflector, which measures 39 feet (12 metres) wide,“ the largest NASA has ever sent into space.

The NISAR mission is a partnership between NASA and ISRO spanning years of technical and programmatic collaboration. The successful launch and deployment of NISAR builds on a strong heritage of cooperation between the United States and India in space.