The NASA-ISRO Synthetic Aperture Radar or NISAR satellite has officially entered the science phase. In a statement released Friday, ISRO shared a picture of a key Indian ecosystem captured by the satellite’s S-Band antenna, after the successful deployment of its massive 12-metre radar antenna reflector.
The antenna, which is attached to a 9-metre boom, was launched in a stowed condition because such a large structure can’t fit inside a rocket fairing. Over five days, engineers slowly unfolded the boom in stages like extending the joints of a robotic arm, and on August 15, the boom was fully opened and tests showed it is working properly.
Since August 19, NISAR’s S-band radar built by ISRO has been imaging the Indian landmass. ISRO had deployed reference targets such as corner reflectors around Ahmedabad, Gujarat to fine-tune the instrument. The Amazon rainforests were also used for calibration purpose. Announcing the commencement of NISAR’s science phase, the agency also released a picture of the Godavari delta in Andhra Pradesh rich with various vegetation classes like mangroves, agriculture, arecanut plantations and acquaculture fields.
“Initial analysis by scientists and engineers revealed the potential of S-Band SAR data for various targeted science and application areas like agriculture, forestry, geo-sciences, hydrology, Polar/Himalayan ice/snow and oceanic studies,” ISRO said adding that that delta image, “highlights NISAR’s S-Band SAR ability to map river deltas and agricultural landscapes with precision.”
All about NISAR
The $1.5 billion NISAR is the world’s most expensive Earth observation satellite jointly built by NASA and ISRO. It launched on July 30 atop ISRO’s GSLV F16 rocket, and it’s currently orbiting Earth in a Sun-synchronous polar orbit at an altitude of approximately 750 kilometers (466 miles).
The satellite is tasked with tracking motion of ice sheets and glaciers, the deformation of land due to floods, earthquakes, volcanoes, wildfires, oil spills and landslides, along with changes in forest and wetland ecosystems down to a centimeter. Besides, it will also provide invaluable information for disaster response, infrastructure monitoring and food security.
While the L-Band system by NASA will see through clouds and forest canopy, the S-Band system by ISRO will penetrate cloud covers. The S-band is also highly sensitive to light vegetation and moisture in snow and both radars will be utilised during the day as well as night. NASA says that NISAR will make detailed measurements of our planet every 12 days, documenting the slightest of planetary changes over five years.
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