Storyteller from Space

On July 30, 2025, NASA and the Indian Space Research Organization (ISRO) launched the NASA-ISRO Synthetic Aperture Radar satellite, known as NISAR. This satellite will observe nearly all of Earth’s land and ice surfaces, detecting even centimeter-level changes in the Earth’s surface, and observing characteristics of ice sheets, glaciers, and terrestrial ecosystems. 

Paul Siqueira, professor of electrical and computer engineering and co-director of the Microwave Remote Sensing Laboratory (MIRSL), is the ecosystems lead on this project, responsible for ushering mission requirements in the measurement of forest biomass, disturbance, agriculture, and wetlands. 

“NISAR is Earth’s ecosystem storyteller from space,” Siqueira says. “I think that many people are well aware of what the environment is like in their own backyard, their town, and in the surrounding areas.” 

However, he explains, we are less aware of what is happening over extended regions or in remote parts of the planet. Satellites offer a unique view into these areas that are generally inaccessible. “A synoptic view, from space, of the world around us, and how it is changing over time, is important for learning more about life on our home planet and helps us to better apportion limited resources in support of human and environmental health,” he says. 

The NISAR satellite is uniquely positioned to provide this critical insight. “The orbital period of NISAR means that it’ll be revisiting the exact same orbital track every 12 days, so if you include ascending and descending tracks, that’s two observations every 12 days over all land surfaces globally,” he says. “That’s fundamentally going to change the way that we use data for studying the natural environment.” 

NISAR is the first multi-frequency radar satellite (L- and S-band), resulting in high-resolution images of the Earth’s land and ice surfaces. In radar engineering terms, the L-band operates at longer wavelengths, which allows its signals to penetrate deeper into vegetation and ice, making it well-suited for structure and biomass measurements. The S-band, meanwhile, operates at shorter wavelengths, providing finer sensitivity to surface features. Integrating both bands within a single synthetic aperture radar system requires precise calibration, but ultimately produces complementary measurements that increase accuracy and reduce ambiguity.. 

“In other words, NISAR makes the invisible visible— from subtle changes to the land surface to sweeping changes in forests,” says Siqueira. And the 4.5 terabytes of data collected daily from billions of measurements is open access. 

“Ecosystems represent things like wetlands, forests, and mangroves, all important contributors to biodiversity and the security that underpins natural habitats and societal services such as clean air, clean water, and staple crops that are important for food security,” he says. “We will have a new tool for looking at ecosystem dynamics and the hydrologic cycle that underpins them.” 

He also highlights that NISAR’s short-term observation cycle has a wide range of benefits, including monitoring the health of crops, the impacts of flooding and disasters, and the security of shared resources like forests or wetlands. “In some parts of the world, clouds obscure a satellite’s view of the ground for the majority of the year, making it difficult to detect activities such as illegal logging and mining that pollute the environment and harm those living downstream of the activity,” he says. 

“By understanding how the natural environment, marked by the climate and weather, interacts with the living world of flora and fauna, we can better understand the dynamics that are important for maintaining societal health and well-being.”