What is NASA-ISRO SAR (NISAR) and why is it a historic collaboration?

The answer

Launched on July 30, 2025, NISAR (NASA-ISRO Synthetic Aperture Radar) is the first joint satellite mission between NASA and the Indian Space Research Organisation. It's also the first dual-band (L-band and S-band) radar imaging satellite, capable of mapping nearly the entire Earth's surface every 12 days. NISAR uses radar to see through clouds and darkness, measuring ground displacement down to centimeters - tracking glacial movement, earthquake deformation, groundwater depletion, and forest biomass changes. The $1.5 billion mission represents one of the most significant international space partnerships, with NASA building the L-band radar and ISRO building the S-band radar and spacecraft bus.