MIT professor will lead science team for NASA satellite to map Earth's water cycle

The orbiting SMAP satellite will make simultaneous radiometer and radar measurements using a shared reflector antenna that is rotated to scan the Earth surface. The large 6 meter in diameter... Click here for more information.

“Research conducted by MIT faculty and students is at the forefront of SMAP’s science objectives, and MIT can play an important role in contributing to the mission’s algorithms and science products,” said Njoku, who earned his Ph.D. from MIT in 1976. “MIT students have the opportunity to be involved in many aspects of the mission.”

SMAP’s launch in 2012 is feasible in part because Entekhabi and other scientists continued to develop the mission, even when NASA’s support was withdrawn in 2005.

The instruments that will be deployed in SMAP will gather both passive and active low-frequency microwave measurements on a continuous basis, essentially creating a map of global surface soil moisture. A 6-meter deployable mesh antenna on a satellite will gather data across a swath of 1,000 kilometers, creating ribbons of measurements around the globe and completing the cycle every few days.

In addition to measuring soil moisture, the satellite will detect if the surface moisture is frozen. In forests, the freeze/thaw state determines the length of the growing season and the balance between carbon assimilation into biomass and the loss of carbon due to vegetation respiration. The result of this balance can tell scientists if a forest is a net source or net sink of carbon.

One mission obstacle that Entekhabi and team solved last year was integrating the two types of measurements the satellite would gather: passive measurements collected by radiometer, and active collected by radar. The radiometer measurements provide highly accurate data at a coarse resolution of 40 kilometers. The radar measurements provide much higher resolution (3 kilometers), but with less sensitivity. The combination of the two measurements through algorithms designed by the SMAP science team will result in accurate mapping of global soil moisture at 10 km.

Entekhabi is the Bacardi and Stockholm Water Foundations Professor in the Department of Civil and Environmental Engineering and the Department of Earth, Atmospheric and Planetary Sciences.

MORE INFO: http://smap.jpl.nasa.gov/

NASA contact: Alan D. Buis, NASA Jet Propulsion Lab, 818-354-0474