The launch of the world’s first remote sensing satellite, Sputnik 1, heralded the era of remote sensing. Since that epic moment in 1957, hundreds of Earth observation satellites have enhanced the understanding of the planet. The NISAR satellite, launched on Wednesday, will capture details on the Earth’s surface, which are stunning even by the high standards set in remote sensing in the past 68 years. The satellite, jointly operated by India’s premier space research agency ISRO and NASA, will generate 80 TB of data every day, three times more than any other existing Earth observation systems. It will enhance the understanding of ecosystems and enable the study of natural hazards such as earthquakes and landslides at a time when the chances of such environmental threats are much higher compared to any other period in recent human history. NISAR’s radar systems will scan nearly all the planet’s land and ice surfaces twice every 12 days, tracking shifts as slight as a centimetre. The satellite will be able to see through clouds, smoke, and even thick vegetation, both during the day and at night, in all weather conditions. The information is likely to be available in a matter of hours, enabling governments and even local communities to frame urgent responses during extreme weather events such as floods and storms. NISAR, therefore, promises to be a game-changer in disaster management.
The satellite’s power comes from its two synthetic aperture radars (SARs), which are designed to capture complementary sets of images for the same location at the same time. This will provide a much more detailed view of the Earth compared to what has been possible so far. One of the radars can capture minute details, including the planet’s undulations, and study trees even in dense forests — this can help estimate carbon stocks. The other SAR, which has a shorter wavelength, is equipped to capture features such as water bodies or fields and provide data on soil moisture and the maturity stages of crops. This could help agriculture research agencies pass on crucial information to farming communities.
Placing two SARs on one satellite was a major engineering challenge. That’s one reason NISAR was more than 15 years in the making. The project was initiated by NASA in 2008. ISRO joined the endeavour four years later. The Indian space agency’s contribution was crucial to the mission. It designed and built one of the radar systems, created the data handling and downlinking systems and provided NISAR’s launch vehicle, the GSLV-F16. The collaboration was spared the funding cuts inflicted on NASA by the Trump administration. Its success is a message to the US President that high science is almost impossible without meaningful partnerships between nations.
