Soil Moisture Active Passive (SMAP)

The Soil Moisture Active Passive (SMAP) mission is a NASA satellite-based observatory designed to provide global measurements of soil moisture and its freeze/thaw state. Launched in 2015, SMAP forms a critical component in understanding our planet's water cycle, weather, and climate patterns. The mission's data is crucial for enhancing forecasting abilities for weather and climate, improving flood and drought predictions, and assisting in agricultural productivity assessments.

Mission Overview

SMAP is an integral part of NASA's Earth observation satellite program. Its main goal is to consistently measure the moisture content in the Earth's topsoil. The satellite orbits the Earth in a polar orbit, allowing it to cover the entire globe every two to three days.

The satellite is equipped with both an active radar and a passive radiometer, technologies that allow it to measure soil moisture at depths of up to 5 centimeters with unprecedented accuracy. The active radar sends microwave pulses to the Earth's surface and measures the backscatter, while the passive radiometer detects naturally emitted microwave radiation from the soil.

Technology and Instruments

Active and Passive Remote Sensing

SMAP utilizes both active and passive remote sensing techniques. Active sensing involves the use of the L-band radar, which transmits microwave signals and receives the reflected signals from the Earth's surface. This method provides high-resolution data on the surface texture and moisture.

The passive radiometer, on the other hand, measures the natural emissions from the Earth’s surface. This combination allows SMAP to provide comprehensive data sets that detail not only soil moisture levels but also the state of soil freeze/thaw cycles.

Scientific and Practical Applications

SMAP's data has numerous applications in science and practical fields:

Climate Research: By providing detailed moisture data, SMAP aids in understanding the complex interactions between the land surface and atmosphere, crucial for climate modeling.
Agriculture: Farmers rely on SMAP data to make informed decisions about irrigation and crop management, optimizing water resources for agricultural productivity.
Hydrology: SMAP helps in monitoring and predicting hydrological events such as floods and droughts, providing valuable data for disaster readiness and management.
Environmental Monitoring: The mission offers insights into the impacts of environmental changes, such as deforestation and urbanization, on the Earth's water cycle.

Key People and Collaborations

The SMAP mission has been led by a team of distinguished scientists and engineers. Dara Entekhabi, a prominent figure in hydrologic sciences, served as the science team leader. Eni G. Njoku was instrumental as the project scientist, and Kamal Sarabandi contributed significantly as a member of the science team.

SMAP also collaborates with citizen scientists through platforms like SciStarter, enhancing the mission's ground data collection and validation processes. This partnership broadens the reach and impact of SMAP's research findings.