New SA instrument to accurately measure Earth’s soil

Washington, December 31: SA is all set to launch an instrument that will measure the moisture lodged in Earth’s soils with unprecedented accuracy and resolution. Scheduled for launch on Jan 29, the Soil Moisture Active Passive (SMAP) instrument has a radar, a radiometer and the largest rotating mesh anten ever deployed in space.

The mission’s science instrument ropes together a sensor of each type to corral the highest–resolution, most accurate measurements ever made of soil moisture – a tiny fraction of Earth’s water that has a disproportiotely large effect on weather and agriculture, the US space agency said in a statement.

Remote sensing instruments are called “active” when they emit their own sigls and “passive” when they record sigls that already exist.

To eble the mission to meet its accuracy needs while covering the globe every three days or less, SMAP engineers at SA’s Jet Propulsion Laboratory in Pasade, California, designed and built the largest rotating anten. SMAP’s radar uses the anten to transmit microwaves toward Earth and receive the sigls that bounce back called backscatter. SMAP’s radiometer detects differences in Earth’s tural emissions of microwaves that are caused by water in soil. (IANS)