If you need to know if the plants in your house need watering, all you have to do is stick your finger into the soil.  The same goes for your lawn.  However, if you want to check the soil moisture in Dubai, that might be a bit trickier. But not for long. Thanks to a new satellite developed by NASA, and set to launch into Earth's orbit at the end of the month, soon you will be able to check on the moisture content of the whole planet with the click of a mouse.

The Soil Moisture Active Passive satellite, or SMAP, is scheduled for launch at 9:20 am ET on January 29 from Vandenberg Air Force Base in California. And aside from being the first soil moisture analyzer NASA has ever launched into space, the satellite has the largest rotating mesh antenna ever deployed, with a diameter of six meters.

"We call it the spinning lasso," said Wendy Edelstein, the SMAP instrument manager said in a NASA press release.

Because of its size, the NASA Jet Propulsion Lab's engineers had to build it in a way so that it could be compressed into a 30 x 120 centimeter space for the launch.

"The antenna caused us a lot of angst," Edelstein says.

The SMAP will use two microwave instruments to map the globe every couple of days, and will measure the moisture in the top 2 inches of the soil.  These readings will give both scientists and farmers the most detailed soil moisture maps to date, and will give them an early warning about impending droughts.

Farmers will find the drought warnings useful, as they will be able to use the information to vary irrigation patterns, delay planting times and try other strategies to cope with any potential drought.

"Agricultural drought occurs when the demand for water for crop production exceeds available water supplies from precipitation, surface water and sustainable withdrawals from groundwater," said Forrest Melton, a research scientist in the Ecological Forecasting Lab at NASA Ames Research Center in Moffett Field, California. "Based on snowpack and precipitation data in California, by March we had a pretty good idea that by summer we'd be in a severe agricultural drought."

"But irrigation in parts of India, the Middle East and other regions relies heavily on the pumping of groundwater during some or all of the year."

Underground water resources are hard to estimate, so farmers who rely on groundwater have fewer indicators of approaching shortfalls than those whose irrigation comes partially from rain or snowmelt. For these parts of the world, where farmers have little data available to help them understand current conditions, SMAP's measurements could fill a significant void.

Currently, farmers must rely only on their experience to predict drought conditions.  Hopefully, the SMAP will give them a more objective assessment of soil moisture so they can make much more accurate predictions, says NASA.

SMAP researcher at NASA's Jet Propulsion Laboratory, Narendra Das says "SMAP can assist in predicting how dramatic drought will be, and then its data can help farmers plan their recovery from drought."