NASA to track soil moisture from space with SMAP satellite

Water, water everywhere but how much in the soil?

That's the question NASA's newest satellite SMAP (Soil Moisture Active Passive) aims to answer when it launches later this month.

"It will focus on the water that lives and moves through the soil," said NASA scientist Christine Bonniksen.

Soil moisture is an important predictor of droughts, floods and other weather patterns, but up until now there hasn't been a good way of monitoring it on a global level.

SMAP will provide regularly updated data that will be useful for farmers and forecasters alike.

The $916 million dollar machine looks sort of like a small refrigerator carrying a large, golden umbrella. That umbrella is actually an antenna attached to a spinning mechanical arm.

It sends microwaves down to Earth that are partially absorbed and partially reflected by the water in the top two inches of soil.

The waves that bounce back into space are read by the satellite and help paint a picture of how dry any patch of land is.

"This information will improve our knowledge, weather, climate over land as well as water related hazards," Bonniksen said during a recent press conference Thursday.

Soil moisture is a relatively small amount of Earth's over all water supply, just 0.001% of all Earth's water and 0.05% of its freshwater.

Still, SMAP scientist Dara Entekhabi says it plays an outsized role in the ecosystem.

"It’s what’s interacting with the vegetation, it’s what’s determining how much runoff occurs, how much fresh water there is in the rivers and lakes. So it’s a tiny amount but a very important amount,” he said. 

Entekhabi says that by monitoring soil moisture researchers can tell if a region is drying up and possibly heading toward a drought or if an area is already too wet and could see floods after heavy rains.

Once operational, SMAP will produce a global map of soil moisture within three days and  update that map with each orbits.

The US Drought Monitor, the Forest Service and Department of Agriculture are all hoping to use the data as soon as it’s available.

SMAP is set to launch from Vandenberg Air Force Base in California on January 29th.