A groundbreaking satellite has recently entered orbit to monitor the Earth’s changing surfaces, detecting even minuscule movements of the planet’s crust. This revolutionary tool comes equipped with a giant radar antenna, ingeniously folded like an umbrella, which has now successfully unfurled, marking a significant milestone in the NISAR mission.
The NISAR mission, a collaborative effort between NASA and the Indian Space Research Organisation (ISRO), launched on July 30 from the Satish Dhawan Space Centre in India. Over two weeks post-launch, the satellite successfully deployed its massive antenna reflector, which spans an impressive 39 feet (12 meters) wide, making it the largest antenna ever utilized in a NASA mission.
The deployment process began on August 9, as the team meticulously unfolded the satellite’s boom one joint at a time. Following this, small explosive bolts were fired to lock the antenna into position, successfully completing a critical stage of the mission. According to Phil Barela, NISAR project manager at NASA’s Jet Propulsion Laboratory in Southern California, the team was eager to see the deployment succeed, as it has been a crucial part of the NISAR Earth science initiative, developed over many years of design and testing.
Now that the satellite is in orbit, the focus has shifted to fine-tuning the systems in preparation for delivering transformative scientific data by late fall this year.
The NISAR satellite, which stands for NASA-ISRO Synthetic Aperture Radar, aims to provide groundbreaking three-dimensional views of the Earth’s surface in unprecedented detail. This mission features the most advanced radar systems ever created for a NASA mission. The antenna reflector is integral to NISAR’s two synthetic aperture radar (SAR) systems, crucially utilizing the movement of the radar antenna over designated areas to create high-resolution imagery.
Paul Rosen, NISAR’s project scientist at JPL, likened synthetic aperture radar to a camera lens that focuses light to render sharp images. The size of this lens, or aperture, determines the image’s clarity. The first radar system, known as L-band, is capable of penetrating clouds and forest canopies. Meanwhile, the second system, an S-band radar provided by ISRO, also pierces cloud cover but demonstrates heightened sensitivity to light vegetation and moisture in snow.
Weighing approximately 142 pounds (64 kilograms), the reflector is assembled from 123 composite struts encased in a cylindrical frame, topped with a gold-plated wire mesh. The unfolding process of NISAR’s boom took four days to achieve full extension, with a series of small explosive bolts being activated on August 15 to initiate the “bloom” process. This process allowed for the antenna to unfurl by releasing tension stored in its flexible frame, similar to an umbrella opening. Following this, motors and cables were engaged to guide the antenna to its ultimate form.
Spanning an area comparable to the length of a school bus, the reflector empowers NISAR to capture images of the Earth’s surface with pixel accuracy reaching approximately 30 feet (10 meters) across. Using advanced interferometric techniques that compare successive images over time, researchers will be able to create three-dimensional visualizations of changes occurring on Earth’s surface, as stated by Paul Rosen.
image source from：gizmodo
