Spacecraft with a lasso on top set for launch

(CNN REPORT) If your houseplants look thirsty, you can stick your finger in the soil to see if they need water. But if you want to check the whole planet's moisture level, you need something a bit more high tech.

NASA has just the thing. It's called the Soil Moisture Active Passive, or SMAP, satellite. It's currently scheduled to launch at 6:20 a.m. PT (9:20 a.m. ET) on January 29 from Vandenberg Air Force Base in California.

The satellite has the largest rotating mesh antenna ever deployed in space.

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

The antenna is 19.7 feet (6 meters) in diameter. Engineers at NASA's Jet Propulsion Lab had to build it so that it could be squished into a one foot by four feet (30 by 120 centimeters) space for launch.

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

SMAP will use two microwave instruments to map the globe every couple of days, measuring moisture in the top 2 inches (5 centimeters) of the planet's soil. It will give scientists and farmers the most detailed soil moisture maps yet -- and give them an early warning about droughts.

If farmers know a drought is coming, they can change irrigation patterns, delay planting or use other tactics to try to save their crops.

Right now, farmers make those predictions based on their experience. SMAP will give them an objective assessment of soil moisture, NASA says.

"SMAP can assist in predicting how dramatic drought will be, and then its data can help farmers plan their recovery from drought," said Narendra Das, scientist on SMAP's science team at the Jet Propulsion Laboratory in Pasadena, California.