NASA’s Newest Satellite Will Prevent Droughts and Predict Floods

SMAP, scheduled to launch on January 29, is the latest of the agency's ambitious Earth science missions.

Jan 4 2015, 8:36pm

Image: NASA

​Over the past few years, NASA has been actively bolstering its fleet of climate-focused satellites. From launching the Orbiting Carbon Observatory 2 on July 2, 2014, to greenlighting a satellite that will monitor Earth's forests in 3D, the agency is ramping up research on the planet's environmental health, and for good reason, as a brief stroll through our "climate change" tag will attest.

Over the holidays, the latest addition to this club of orbital Earth-watchers finally received a new launch date after months of delays. The Soil Moisture Active Passive (SMAP) satellite is scheduled to be launched on January 29 from Vandenberg Air Force Base. If all goes according to plan, SMAP will be NASA's fifth Earth science mission to reach orbit over the last twelve months, and will provide space-down insights into the behavior of soil moisture around the world.

"On a global scale, there are important gaps in knowledge of where water is stored, where it is going, and how fast it is moving," the mission leads wrote in the SMAP Handbook. SMAP is designed to bridge those gaps by measuring the global soil moisture content in unprecedented detail every three days, or less. The data it collects will help prevent droughts, prepare for floods, estimate crop yields, and generally improve our understanding of how ground water content relates to carbon cycles and climate stability—vital information for an ever-growing human population.

SMAP mission overview. Credit: NASA-JPL/YouTube.

But perhaps the most interesting aspect of the SMAP mission is its utterly idiosyncratic design. The satellite is decked out with the largest rotating mesh antenna ever created, measuring 19.7 feet (six meters) in diameter.

"We call it the spinning lasso," said Wendy Edelstein, SMAP's instrument manager, in a NASA statement. Indeed, the antenna is even rigged to a robotic arm with a crooked "elbow," which will spin it around much like a cowboy's lariat. Propelled by the arm, the antenna will rotate once every four seconds, a dynamic that allows the other two main instruments, ​a radar and a radiometer, to image soil moisture with microwave signals.

Figuring out how to fit this massive structure into a one foot by four foot capsule proved to be a major design challenge for the SMAP team. "The antenna caused us a lot of angst, no doubt about it," Edelstein said.

"Making sure we don't have snags, that the mesh doesn't hang up on the supports and tear when it's deploying—all of that requires very careful engineering," she continued. "We test, and we test, and we test some more. We have a very stable and robust system now."

Once the carefully packed antenna deploys, SMAP will be able to begin its study of the Earth's soil, in tandem with NASA's growing fleet of Earth-centric satellites. Given that 2014 produced some of the most punishing droughts and floods in recent years, the spacecraft is a welcome addition to the planet-watching team.