NASA-ISRO Synthetic Aperture Radar (NISAR): The Last Steps to Launch

As NASA & ISRO teams prepare to operate the NASA-ISRO Synthetic Aperture Radar (NISAR) to make unparalleled Earth observations, the spacecraft is undergoing integration & test of the spacecraft bus and radar payload to prepare for launch.NISAR is a multi-disciplinary Earth-observing dual-band radar mission being jointly developed by NASA and the Indian Space Research Organization (ISRO). As a pathfinder for NASA’s Earth System Observatory (ESO), NISAR will make global measurements of land surface changes from its near-polar 12-day repeating orbit, for integration into Earth system models. NISAR provides a means of understanding spatially and temporally complex phenomena, ranging from ecosystem disturbances to ice sheet collapse and natural hazards including earthquakes, tsunamis, volcanoes, and landslides. In addition to enabling scientific advances, NISAR will provide societally relevant data that will enable investments to protect human life and property.After several years of buildup and test at JPL, the NASA-developed L-band SAR, an ISRO-developed S-band SAR, a deployable 12m radar antenna, and an Engineering Payload have met the ISRO built spacecraft bus at the ISITE facility in Bangalore. While the System Integration & Test (SIT) activities at JPL integrated the L- and S- band SARs with the Engineering Payload, the integration of the bus in India has challenged both teams to understand how the other operates and work together towards a successful mission.In this year leading to launch, the team is:• Mechanically & electrically integrating the full spacecraft, including bus, payloads, and reflector antenna assembly. This includes integration of components inside the spacecraft bus in addition to the reflector antenna assembly and Radar Instrument Structure (RIS).• Testing the observatory in increasing scope & complexity of activities from checkouts to full scenarios, including faulted tests and environmental testing. Testing involved multiple organizations delivering command products and coordinated through an automated tool.• Preparing for operations through Operational Readiness Tests (ORTs) and compatibility testing. This includes development of a novel test venue to support these tests as well demonstrating data flow and coordination around the globe.• Combining an ISRO and JPL testbed at the U.R. Rao Satellite Center (URSC). The venue allows for risk reduction testing and fault scenario testing not possible in the flight venue. In addition, it can provide a valuable resource for launch and early operations testing. In parallelAlong the way, the team has dealt with some technical challenges requiring late integrations and rework, including regression testing, and replanning critical activities as the resources and plans shifted.This paper discusses the test results and design challenges of the final SIT campaign, the trials that are still ahead, and the verification and validation activities that were conducted through-out.