The joint NASA and ISRO NISAR mission, dedicated to Earth science, is set for launch in late March 2025, following a delay for antenna repairs. Gerald Bawden, program scientist for the mission at NASA Headquarters, announced the updated launch window at the American Geophysical Union's annual meeting on December 11th.
Originally scheduled for spring 2024, the launch was postponed in March due to issues with the spacecraft's 12-meter deployable reflector. Engineers discovered that the reflector would overheat during orbit after launch. This required transporting the antenna from India to California for repairs.
NASA completed these repairs by October, returning the antenna to India via a C-130 aircraft. While a launch window between October 2024 and February 2025 was deemed unsuitable due to orbital sunlight and shadow patterns, Bawden confirmed that the reflector issue, discovered during thermal vacuum chamber testing, involved "temperatures higher than expected." The solution was applying reflective tape to black rods within the reflector. Bawden stated, “Some of the temperatures were higher than we expected them to be,” and added, "We are set now with NISAR. The hardware is completely checked out."
The spacecraft is currently in storage. This is partly due to waiting for an eclipse period to end on February 8th, and partly because the launch pad at India's Satish Dhawan Space Centre needs to be refurbished after the launch of the NVS-02 navigation satellite, currently scheduled for mid-January. Bawden explained, “Once it launches, it’s going to take six to eight weeks to refurbish the launch pad” before NISAR can launch. The mission targets a launch no earlier than late March.
NISAR will employ L- and S-band radars for comprehensive global land and ice mapping. The advanced radar imaging will contribute to various Earth science applications, from glacier flow rate measurement to monitoring volcanic activity. Bawden anticipates science operations commencing approximately three months post-launch.
This mission signifies a major collaboration between NASA and ISRO, with NASA contributing over $1 billion to its development. NASA provides the L-band radar and engineering payload, while ISRO provides the S-band payload, spacecraft bus, and GSLV launch vehicle.