BENGALURU: The 12-metre diameter unfurlable giant radar antenna reflector on the National Aeronautics and Space Administration (NASA)-Indian Space Research Organization (ISRO) Synthetic Aperture Radar (NISAR) satellite, has completely unfurled 17 days after the July 30 launch from the second launch pad of Satish Dhawan Space Centre in Sriharikota.
Terming it as a giant radar measuring 39 feet, NASA said it is a critical part of the five-year long NISAR mission.
NASA explained that the antenna reflector is an essential component of the satellite’s hardware. Weighing about 142 pounds (64 kilograms), the reflector features a cylindrical frame made of 123 composite struts and a gold-plated wire mesh. On August 9, the satellite’s 9-metre boom – which had been tucked close to its main body – started unfolding one joint at a time until it was fully extended about four days later.
The antenna reflector assembly is mounted at the end of the boom. Then, on August 15, small explosive bolts that held the reflector assembly in place were fired, enabling the antenna to begin a process called the “bloom” — its unfurling by the release of tension stored in its flexible frame while stowed like an umbrella. Subsequent activation of motors and cables then pulled the antenna into its final, locked position.
ISRO said this is one of the milestones for NASA-JPL and ISRO that has been achieved.
The scientific tasks of the $ 1.5 billion NISAR mission are scheduled to commence 90 days after the satellite was launched on July 30. These 90 days are being dedicated to commissioning and preparing NISAR for science operations and other activities, including calibrations and initial checks. One of them was stationing the radar antenna reflector and checking its functioning.
Former ISRO Chairman S Somanath took to “X”, saying the antenna was in "full bloom".
He said: “This systematic deployment — driven by multiple motor actuators and intricate cabling — faced many challenges. Some of the challenges involved were thermal behaviour of composite structures which was critical for the opening process. Understanding and ensuring safe deployment was one of the reasons for the delay of launch in 2024. Delighted to see this complex step completed safely.”
He said that next will be the payload tests and calibrations in the weeks ahead, and added that it is a giant leap for Earth observation.
The NISAR satellite has been deployed in its designated Sun Synchronous Polar Orbit (SSPO) at an altitude of 747kms. The NISAR is assigned to track land, ice and sea and take images once every 12 days. The all-weather, day-night satellite will also assess any deformations on land due to earthquakes, volcanoes, landslides, changes in forest cover, wetlands and other ecosystems, and issue alerts about impending natural disasters.