NISAR Data: What Is Free, What It Measures and Where It Goes
NASA and ISRO’s NISAR satellite uses two radar wavelengths to measure changes in land and ice, with mission data and products designated free and open.
Timeline
- July 30, 2025: NISAR launched from the Satish Dhawan Space Centre in India.
- Three-year baseline mission: The satellite is designed to collect repeated observations of land and ice.
NISAR, short for NASA-ISRO Synthetic Aperture Radar, launched on July 30, 2025 from the Satish Dhawan Space Centre in India. The joint mission carries an L-band radar supplied by NASA and an S-band radar supplied by the Indian Space Research Organisation to observe changes across Earth’s land and ice surfaces. [1][2]
The mission’s data and products are designated free and open. NASA lists the Alaska Satellite Facility as an access point for L-band data. ISRO’s Bhoonidhi portal distributes S-band products and L-band coverage for India and selected sites, so the appropriate repository depends on the requested instrument, area and product. [2]
Synthetic-aperture radar sends microwave signals toward Earth and measures the returned energy. Unlike an ordinary photograph, the result can reveal surface structure and change even through clouds and without daylight. Comparing observations from different passes can show small movements rather than merely producing a familiar-looking image. [1][2]
NISAR has an exact 12-day orbit repeat cycle. It observes from ascending and descending passes, producing an average revisit of about six days over many locations. A revisit is another opportunity to observe an area; it does not mean every final product for every location is published precisely every six days. [1][2]
NASA says the measurements can support studies of vegetation, groundwater movement, sea-level-related processes, glaciers, sea ice and natural hazards. Repeated radar observations can also help analysts examine deformation near volcanoes, earthquakes and infrastructure. The data provide evidence of surface change, while interpretation still requires suitable models and supporting information. [1][2]
The two wavelengths respond differently to surface features. NASA lists L-band at about 24 centimeters and S-band at about 9.4 centimeters. L-band can interact with larger vegetation structure and penetrate farther into some surfaces, while the shorter S-band adds complementary measurements. Instrument mode and processing level affect resolution and meaning. [2]
Free access does not make every product instantaneous or identical. Raw observations must be downlinked, calibrated and processed, and higher-level products may use additional algorithms. Researchers should read product documentation, quality information and acquisition metadata before comparing dates. NISAR’s baseline science operations are planned for three years, with possible extended operations afterward. [2]