WASHINGTON — NASA’s Soil Moisture Active Passive (SMAP) satellite on Oct. 15 arrived at Vandenberg Air Force Base, California, where it will be mated with the United Launch Alliance Delta 2 rocket slated to launch it into a near-polar orbit Jan. 29.

SMAP, an Earth observatory designed to produce a global map of soil moisture every two to three days over a three-year primary mission, will operate in a 685-kilometer, near-polar, sun-synchronous orbit that crosses the equator around 6 a.m. and 6 p.m. local time. SMAP will pass over the same spot every eight days. The spacecraft’s synthetic aperture L-band radar and L-band radiometer will observe in a 1,000-kilometer measurement swath and gauge the moisture of the top two inches of Earth’s surface, NASA said.

NASA’s Jet Propulsion Laboratory in Pasadena, California,  built the spacecraft and the radar, while NASA’s Goddard Space Flight Center in Greenbelt, Maryland, built the radiometer. Northrop Grumman’s Astro Aerospace business unit in Carpinteria, California, built a reflector boom assembly.

SMAP data will provide insight into the global water and carbon cycles, aiding weather forecasters, farmers, foresters and emergency planners, among others, according to NASA. The mission will cost around $915 million to build and launch, the U.S. Government Accountability Office said in an April report, “NASA: Assessments of Selected Large Scale Projects.”

SMAP is one of the major missions endorsed by scientists in a 10-year Earth science plan known as a decadal survey the National Research Council published in 2007.

Dan Leone is a SpaceNews staff writer, covering NASA, NOAA and a growing number of entrepreneurial space companies. He earned a bachelor’s degree in public communications from the American University in Washington.