NISAR

NISAR. The NASA-ISRO Synthetic Aperture Radar mission is a pioneering joint venture between the National Aeronautics and Space Administration and the Indian Space Research Organisation. This low-Earth orbit observatory is designed to measure changes in our planet's surface with unprecedented detail, using advanced dual-frequency radar imaging. The mission represents a landmark in international cooperation for Earth science and aims to provide a continuous, global view of Earth's most complex processes.

Overview

The mission is a flagship collaboration, integrating the technological expertise of the Jet Propulsion Laboratory and the ISRO Satellite Centre. It operates in a Sun-synchronous orbit, ensuring consistent lighting conditions for its observations over the mission's planned three-year duration. By employing an innovative synthetic-aperture radar system, it can penetrate cloud cover and vegetation, collecting data day and night regardless of weather. This capability is critical for monitoring dynamic phenomena across the cryosphere, Earth's crust, and biomass worldwide.

Mission objectives

Primary goals include tracking subtle changes in Earth's crust associated with earthquakes, volcanoes, and landslides to improve hazard forecasting. The mission will systematically measure the dynamics of ice sheets in Greenland and Antarctica, contributing vital data to studies of sea level rise. Furthermore, it will monitor the distribution and changes in global vegetation and wetland ecosystems, providing insights into the carbon cycle and climate change. These observations are essential for informing policies related to disaster management and environmental protection.

Scientific instruments

The core payload consists of two fully polarimetric synthetic-aperture radar instruments. The L-band radar, provided by NASA, operates at a wavelength of approximately 24 centimeters, ideal for penetrating vegetation canopies and measuring ground deformation. The S-band radar, provided by ISRO, operates at a wavelength of about 9 centimeters, offering higher sensitivity to smaller-scale surface features and moisture. Both radars are mounted on a large, deployable 12-meter reflector antenna, a technological marvel built by MDA. This dual-frequency approach allows for the decomposition of scattering mechanisms from complex landscapes.

Spacecraft and launch

The spacecraft bus is based on the ISRO I-3K satellite platform, modified to accommodate the large radar payload and its power demands. It will be launched aboard an Indian Geosynchronous Satellite Launch Vehicle from the Satish Dhawan Space Centre on Sriharikota. Key challenges in the design involved managing the thermal loads from the powerful radar instruments and ensuring precise attitude control for accurate imaging. The mission life is designed for three years, with a goal for extended operations, and all data will be freely available to the international scientific community.

Data applications and impact

Data products will revolutionize monitoring of groundwater resources in regions like the Central Valley of California and the Indo-Gangetic Plain. They will enhance our understanding of deforestation impacts in the Amazon rainforest and boreal forests of Siberia. For cryosphere science, data will detail the flow of glaciers in the Himalayas and Patagonia, and the stability of ice shelves in the Weddell Sea. The open-data policy ensures findings will support agencies like the United States Geological Survey and international bodies such as the Intergovernmental Panel on Climate Change, shaping global environmental policy.

Category:NASA spacecraft Category:ISRO spacecraft Category:Earth observation satellites