NISAR Satellite launched: NASA-ISRO $1.5 billion powerful Earth-monitoring satellite takes off from Sriharikota

Economic Times

2 days ago

Marking a major milestone in Indo-US space collaboration, the Indian Space Research Organisation (ISRO) and NASA on Wednesday launched their most advanced Earth observation radar satellite from Sriharikota. Equipped to detect even the slightest changes in the planet's land and ice surfaces, the satellite will play a crucial role in forecasting both natural disasters and human-induced hazards.The first-ever hardware collaboration between NASA and ISRO on an Earth-observing mission, NISAR will carry the most advanced radar system ever launched as part of a NASA or ISRO mission. The satellite also is carrying a price tag of $1.5 billion, making it the most expensive Earth observation mission ever launched. Short for NASA-ISRO Synthetic Aperture Radar, NISAR will help scientists better understand processes involved in natural hazards and catastrophic events, such as earthquakes, volcanic eruptions, and landslides. In addition, it will support monitoring of infrastructure, such as dams, bridges, and roadways. What's more, the satellite's cloud-penetrating ability will help urgent-response communities during weather disasters such as hurricanes, storm surges, and floods. And NISAR will provide key global Earth observations, such as changes in ice sheets, glaciers, and sea ice, as well as improve understanding of how deforestation, permafrost loss, and fires affect the carbon cycle.
What are key features of NISAR?
About the length of a pickup truck, the satellite's main body contains engineering systems and a first-of-its-kind dual-radar payload — an L-band system with a 10-inch (25-centimeter) wavelength and an S-band system with a 4-inch (10-centimeter) wavelength. Each system's signal is sensitive to different sizes of features on Earth's surface, and each specializes in measuring different attributes, such as moisture content, surface roughness, and motion. These characteristics are important for studying a variety of natural surface conditions, such as the amount of soil moisture available for vegetation to thrive or if land has subsided over time. When operating together, the satellite's two radars will collect data synchronized in time and location, extending the sensitivity of the measurements to objects on the surface in a broad range of sizes. For example, S-band data will allow more accurate characterization of shorter plants, such as bushes and shrubs, while L-band data will sense taller vegetation, like trees.
What will NISAR do?
NASA describes NISAR as the most advanced radar system it has ever launched.Because radar signals pass through clouds, they are ideal for continual monitoring of the surface.Deformations in Earth's surface could provide early warning of impending natural disasters like volcanic eruptions and landslides. Measurements of ice sheets will reveal which areas are melting and which are growing through accumulated snowfall.The data could also reveal flooded areas that would otherwise be hidden by bad weather, providing help to rescue teams."NISAR is a model for the next generation of Earth-observation capabilities," Karen St. Germain, director of NASA's Earth science division, said Monday during a news conference.
What happens after launch? NISAR will be lifted to orbit on an ISRO rocket known as a Geosynchronous Satellite Launch Vehicle. The orbit will pass close to the North and South Poles at about 464 miles above Earth's surface.The first 90 days will be devoted to deploying the spacecraft, including extending a 39-foot-wide gold-mesh antenna reflector, which looks a bit like a giant beach umbrella.The primary mission is scheduled to last three years. If the spacecraft is still operational at that point, it will be carrying enough propellant to continue for another couple of years.
How does NISAR work? The main part of the spacecraft is 18 feet long and weighs more than 5,000 pounds. Two 18-foot-long solar arrays will generate power.The satellite includes two radar systems. One, built by NASA, will transmit microwaves with a wavelength of 25 feet. The other, built by ISRO, transmits 10-foot-long microwaves. The two wavelengths will provide details at different size scales. For the study of vegetation, the shorter wavelengths will provide more detail about bushes and shrubs, while the longer wavelengths will provide a clearer picture of taller plants like trees.Transmitters on the spacecraft will generate microwave pulses that will bounce off the gold-mesh reflector and travel down to Earth, bounce off the surface and return to the spacecraft.Multiple radar signals along the orbit will be combined to simulate a larger reflector. Bouncing radar signals from multiple angles allows the creation of 3D views.