Updates in Commissioning Timeline for NASA-ISRO Synthetic Aperture Radar (NISAR)

Abstract

The NASA-ISRO Synthetic Aperture Radar Mission, or NISAR, is a multi-disciplinary Radar mission to make integrated measurements to understand the causes and consequences of land surface changes on Earth. NISAR will provide a means of disentangling and clarifying spatially and temporally complex phenomena on Earth, ranging from ecosystem disturbances, to ice sheet collapse and natural hazards including earthquakes, tsunamis, volcanoes and landslides. NISAR is a joint partnership between the National Aeronautics and Space Administration (NASA) and the Indian Space Research Organization (ISRO). The NASA L-SAR and ISRO S-SAR Radar instruments will provide global and complementary datasets with a 12-day repeat cycle, for addressing compelling scientific questions in the fields of Solid Earth deformation, Ecosystems and Cryospheric sciences. The prime Science Phase for NISAR will be three years in duration. Prior to beginning the Science Phase, all the observatory elements, including the spacecraft bus, the Radar payload instruments, the JPL Engineering Payload and the Reflector Boom Assembly will be checked out during the In-Orbit Checkout or Commissioning Phase, which will last for 90 days after launch. During the Commissioning Phase, there will be a step-by-step buildup in capability to full observatory operations, starting with ‘Initial Checkout’, ‘Reflector Boom Assembly Deployment,’ ‘Spacecraft Checkout’ and finally ‘Instrument Checkout’. Updates made to the NISAR Commissioning timeline in the Project's Phase C have focused on further refinement of the Instrument Checkout phase in particular. During this phase, both the L-SAR and S-SAR instruments will be powered on, their performance will be characterized and calibrated, initial calibrations will be performed to develop calibration strategies and demonstrate the instruments are ‘calibratable’ in the following 5 months of Science Calibration/Validation phase during nominal science operations. Initial power-on and calibration activities for L-SAR and S-SAR have been interleaved in the timeline. In addition, investigations of the ground processing activities (for example, data processing, data analysis, uplinks, downlinks) to be performed in between successive calibrations are currently underway. Allocating sufficient time for these ground-in-the-loop activities is critical to the development of a realistic timeline with a healthy margin.