NISAR Mission Begins Crucial 90-Day Calibration Phase

The NASA-ISRO Synthetic Aperture Radar (NISAR) mission, a pioneering collaboration between the U.S. and Indian space agencies, has entered its critical 90-day commissioning phase following its successful launch on July 30, 2025, aboard a GSLV-F16 rocket from Sriharikota, Andhra Pradesh. This phase involves meticulous system checks, calibrations, and orbital maneuvers to prepare the $1.5 billion satellite—the world’s priciest Earth-imaging spacecraft—for its groundbreaking science operations.

Gerald Bawden, NASA’s Program Manager for Natural Hazards Research, told PTI that NISAR, currently at 737 km altitude, will be raised to its target orbit of 747 km over 45-50 days. Once calibrated, the satellite’s dual-frequency L-band (NASA) and S-band (ISRO) radars will begin collecting high-resolution data at 5x5 meters, mapping Earth’s land and ice surfaces every 12 days. “It’s more data than NASA has ever collected from any mission,” Bawden said, highlighting NISAR’s ability to monitor ecosystems, ice sheets, and hazards like earthquakes, volcanoes, and landslides with centimeter precision.

The mission’s innovative SweepSAR technology, combining NASA’s L-band (24 cm wavelength) and ISRO’s S-band (12 cm wavelength) radars, marks a global first, enabling simultaneous observations through clouds and darkness. Sanghamitra Dutta, NASA Earth Sciences Division Program Executive, explained that the concept emerged from brainstorming between ISRO’s Space Applications Centre in Ahmedabad and NASA’s Jet Propulsion Laboratory (JPL). “Two radars at different frequencies allow us to study diverse phenomena, from agricultural growth like corn and soybeans to glacier movements,” she noted.

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NISAR’s data, freely available within 1-2 days (or hours for disasters), will empower global scientists, policymakers, and disaster managers. In India, where climate impacts like Himalayan glacier retreat and monsoon-driven floods are acute, NISAR’s near-real-time insights will enhance water resource management, agricultural planning, and seismic monitoring. The satellite’s 12-meter antenna, set to deploy on August 9, underwent rigorous testing at ISRO’s U.R. Rao Satellite Centre after integration at JPL, ensuring robust performance over its five-year mission life.

The collaboration has deepened Indo-U.S. ties, with Bawden praising ISRO’s focus on societal applications and NASA’s research-driven approach. Despite a 12.5-hour time difference and cultural challenges, the partnership fostered friendships and innovation. Dutta highlighted recent milestones, including Indian astronaut Shubhanshu Shukla’s Axiom-4 mission to the ISS, as evidence of growing space cooperation. “NISAR is a scientific handshake with the world,” said Indian Science Minister Jitendra Singh, noting its role in India’s space ambitions, including Gaganyaan (2027) and a lunar mission by 2040.

The commissioning phase, or In-Orbit Checkout (IOC), includes initial spacecraft checks, antenna deployment, and radar calibration, with validation continuing for five months into science operations. ISRO’s ground stations in Bengaluru and NASA’s JPL will jointly manage the 2,392 kg satellite, orbiting at 98.4 degrees inclination in a sun-synchronous path. Despite a 2024 launch delay due to hardware upgrades, the mission’s July 30 lift-off marked GSLV’s first sun-synchronous orbit success, a relief after ISRO’s recent PSLV-C61 setback.

NISAR’s data will revolutionize Earth science, offering insights into climate change, disaster preparedness, and infrastructure monitoring. For India, it strengthens its global space leadership, with private firms like Skyroot Aerospace eyeing future collaborations. As the satellite prepares to “see” Earth’s faintest shifts, it stands as a testament to international synergy in tackling planetary challenges.

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