NISAR lift-off only in 2024, science Ops to take 90 days after launch | India News


BENGALURU: The Indian Space Research Organisation (Isro) has officially said that the NASA-Isro Synthetic Aperture Radar (NISAR), a low Earth orbit (LEO) observatory being jointly developed by NASA and Isro, “shall be launched from Indian soil in the first quarter of 2024”, and its science operations will begin 90 days after it reaches the intended orbit.
The synthetic aperture radar (SAR) payloads mounted on integrated radar instrument structure (IRIS) and the spacecraft bus are together called an observatory.
The observatory will map the entire globe in 12 days and provide spatially and temporally consistent data for understanding changes in Earth’s ecosystems, ice mass, vegetation biomass, sea-level rise, groundwater and natural hazards including earthquakes, tsunamis, volcanoes and landslides.
“It will carry L and S dual band SAR — the first dual frequency radar imaging mission in L-Band & S-Band using an advanced Sweep SAR technique to provide L & S band space-borne SAR data with high repeat cycle, high resolution, and larger swath,” Isro’s dedicated page for the mission, which went live late on February 3, reads.
US’ Jet Propulsion Laboratories (JPL) and Isro are realising the observatory which shall not only meet the respective national needs but also will feed the science community with data encouraging studies related to surface deformation measurements through repeat-pass InSAR technique, Isro added.
NASA is responsible for providing the L-Band SAR payload system in which the Isro supplied S-Band SAR payload and both these systems will make use of a large size (about 12m diameter) common unfurlable reflector antenna.
In addition, NASA would provide engineering payloads for the mission, including a payload data subsystem, high-rate science downlink system, GPS receivers and a solid state recorder. Isro is responsible for providing the S-SAR data handling system, high-rate downlink system, spacecraft bus systems, the GSLV launch system and mission operations related services.
The observatory carries a 12m wide deployable mesh reflector mounted onto a deployable 9m boom developed by JPL which will be used by both the L-Band and S-Band SAR payload systems.
“The IRIS hosts S-SAR and L-SAR tiles along with their electronics and data handling systems. The spacecraft incorporates all the attitude (orientation) and orbit control elements, power systems, thermal management systems,” Isro added.
“The target launch readiness date is January 2024,” Isro said. The launch sequence encompasses the time interval that takes the observatory from the ground, encapsulated in the launch vehicle fairing, to after separation, and ends with the completion of solar array deployment and the observatory in an Earth-pointed orientation and in two-way communication with the ground. “The launch sequence is a critical event,” Isro added.
According to Isro, the first 90 days after launch will be dedicated to commissioning, or in-orbit checkout (IOC), the objective of which is to prepare the observatory for science operations.
“Commissioning is divided into sub-phases of initial checkout (Isro engineering systems and JPL engineering payload checkout), spacecraft checkout and instrument checkout. Philosophically, the sub-phases are designed as a step-by-step build up in capability to full observatory operations,” Isro said.
The full observation operations will begin with the physical deployment of all deployable parts (notably the boom and radar antenna, but not including the solar arrays which are deployed during launch phase), checking out the engineering systems, turning on the radars and testing them independently and then conducting joint tests with both radars operating.
Science Operations
“The science operations phase begins at the end of commissioning and extends for three years and contains all data collection required to achieve the level-one science objectives. During this phase, the science orbit will be maintained via regular manoeuvres, scheduled to avoid or minimise conflicts with science observations,” Isro said.
Extensive calibration and validation (CalVal) activities will take place throughout the first five months, with yearly updates of 1-month duration. The observation plan for both L-and-S-band instruments, along with engineering activities will be generated pre-launch via frequent coordination between JPL and Isro.

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