It’s not called a doomsday satellite, but NASA-ISRO SAR might be, working on what will eventually be a watchful eye over the ongoing natural disasters, continuing ahead of the expected launch in 2022 or later. A collaboration between NASA and the Indian Space Research Organization (ISRO), the satellite will be the first designed to track changes across almost the entire Earth’s surface, which could provide a vital warning of impending volcanic eruptions or highlight the impact of climate change.
Certainly, volcanoes that are in the middle of an eruption are not difficult to spot, and the same goes for floods from melting ice sheets and rising sea levels. If you want to find out when this can happen in advancealthough this can be a far more complex challenge.
NASA’s synthetic aperture radar – known as NASA-ISRO SAR or NISAR for short – will be a tool to meet this challenge. Although the body of the satellite itself is roughly similar to an SUV, once placed in orbit around the Earth, it will develop a huge wire mesh radar reflector antenna. It will extend to almost 40 feet in height, suspended by NISAR at the end of the 30-foot jib arm.
In addition, NISAR will repel radar signals from the planet’s surface, using reflections to detect small changes in land, ice cover and sea ice. There will be a stunning detail in those measurements: movements of just 0.4 inches, NASA suggests, on surfaces about half the size of a tennis court.
Every 12 days, NISAR is expected to scan the surface of the entire globe. Using the data they collect, scientists expect to be able to spot things like magma movement – which could be a warning sign of imminent volcanic eruptions – or sinking spots that could mean groundwater supplies are depleting. It will also make it possible to monitor the rate of melting of ice sheets related to sea level, and even to monitor changes in the way vegetation is distributed around the world.
This is not an easy task, and NISAR will have very smart hardware to achieve it. Currently under construction at NASA’s Jet Propulsion Laboratory in Southern California, it recently received its SAR band which joins the SAR band L and gives the satellite a unique vision.
The combination of the two types of SARs will unlock far more useful data. The L-band SAR, for example, can penetrate dense vegetation much further: it would be useful to help assess how much there is in forested areas. In contrast, the SAR range is more adept at detecting crop types, along with the rough surface of the Earth. In the coming weeks, the JPL team expects to integrate the electronics of both systems, as ISRO and NASA staff work together to ensure the radars work as intended.
Then they will be mounted on the NISAR satellite itself. If all goes according to plan, the launch is expected in 2022 at the earliest, and the primary mission should last three years.