A Flower - like Satellite Unfolds in Space: NISAR's Groundbreaking Mission

A satellite resembling a blooming flower has manifested in outer space, unfurling to showcase the largest radar antenna reflector ever orbited. The NASA - ISRO Synthetic Aperture Radar (NISAR), a collaborative venture between the United States' National Aeronautics and Space Administration (NASA) and the Indian Space Research Organization (ISRO), was launched on July 30 from the Satish Dhawan Space Center in southeastern India. Seventeen days later, it expanded to its full dimensions.

NISAR's Mission Objectives

The spacecraft is now primed to conduct comprehensive observations of Earth. Employing radar technology, it will track surface changes on our planet with unparalleled resolution. NISAR can precisely record the movement of ice sheets and glaciers, crustal deformation induced by earthquakes and landslides, as well as alterations in forest and wetland ecosystems. For certain terrains, its accuracy can reach a few centimeters. The overarching goal is for NISAR data to facilitate decision - making across a broad spectrum of fields, including disaster response, infrastructure development, agricultural policy - making, and ensuring food security.

Karen St. Germain, the Director of the Earth Science Division at NASA Headquarters, stated in an official release, "The successful deployment of NISAR’s reflector marks a significant milestone in the satellite's capabilities."

A Satellite with Dual - Function "Eyes"

The Antenna Reflector

NISAR's antenna reflector, the apparatus for transmitting and receiving radar signals, spans 39 feet in diameter, making it the largest of its kind ever launched into orbit by NASA. Constructed from gold - plated wire mesh, the reflector was initially attached to the satellite in a folded - umbrella configuration. In the four days following the launch, the satellite gradually extended its boom. Subsequently, on August 15, the antenna frame, which had been under tension, was released, enabling the reflector to "bloom" to its full size.

Dual - Band Radar System

NISAR is the first satellite to be equipped with two types of synthetic aperture radar: L - band and S - band. The L - band has the ability to penetrate forest canopies and clouds, thereby detecting crustal deformation and ice sheet movement. Conversely, the S - band is highly sensitive to moisture in snow cover and changes in vegetation. By integrating these two bands, it becomes possible to record a multi - layered account of diverse phenomena, ranging from earthquakes and volcanic activities to deforestation. The colossal reflector serves as the crucial "eye" for both systems, focusing the transmitted radar signals when they are directed towards Earth and receiving and refocusing these signals upon their return to the satellite.

Paul Rosen, NISAR's project scientist at the Jet Propulsion Laboratory, explained, "Synthetic aperture radar, in principle, operates akin to the lens of a camera, which focuses light to produce a sharp image. The size of the lens, known as the aperture, determines the image's sharpness. By utilizing special interferometric techniques that compare images over time, NISAR empowers researchers and data users to create 3D visualizations of changes occurring on Earth's surface."

Technology Developed Over Decades

Since the 1970s, NASA's Jet Propulsion Laboratory has been actively engaged in developing radars for satellite applications. In 1978, it launched Seasat, the world's first ocean - observing satellite. In the 1990s, it used the planetary probe Magellan to reveal the topography of Venus' cloud - covered surface.

NISAR represents the culmination of decades of accumulated knowledge and is a product of combined US and Indian technology. NASA contributed the L - band SAR and data communications equipment, while India's ISRO was responsible for the S - band SAR and the satellite bus, which manages power, communications, and the satellite's orientation. ISRO's ground station oversaw the launch and initial operations, with experts from both countries collaborating to monitor the deployment process.

Full - scale observations are anticipated to commence by the end of 2025. This will offer something truly unprecedented, as no satellite to date has been capable of tracking environmental changes, such as glacier retreat and deforestation, with a resolution of just a few centimeters. The vast quantity of data collected by NISAR will not only enhance scientific understanding but also provide a foundation for addressing societal challenges. Truly, a new "eye" has been opened to watch over Earth.

This story originally appeared on WIRED Japan and has been translated from Japanese.