6-2015: Soil Moisture- A new NASA satellite that will peer into the topmost layer of Earths soils to measure the hidden waters that influence our weather and climate is in final preparations for a Jan. 29, 2015 dawn launch from California. The Soil Moisture Active Passive (SMAP) mission will measure and help to understand how freshwater cycles over Earths land surfaces in the form of soil moisture. The most accurate, highest-resolution global maps ever obtained from space of the moisture present in the top 2 inches (5 centimeters) of Earths soils will be produced by SMAP satellite measurements. It also will detect and map whether the ground is frozen or thawed. This data will be used to enhance scientists understanding of the processes that link Earths water, energy and carbon cycles. With data from SMAP, we can understand how Earth works as a system and how soil moisture impacts a myriad of human activities, from floods and drought to weather and crop yield forecasts. SMAPs global soil moisture measurements will provide a new capability to improve our understanding of Earths climate. Globally, the volume of soil moisture varies between three and five percent in desert and arid regions, to between 40 and 50 percent in saturated soils. In general, the amount depends on such factors as precipitation patterns, topography, vegetation cover and soil composition. There are not enough sensors in the ground to map the variability in global soil moisture at the level of detail needed by scientists and decision makers. From space, SMAP will produce global maps with 6-mile (10-kilometer) resolution every two to three days. Researchers want to measure soil moisture and its freeze/thaw state better for numerous reasons. Plants and crops draw water from the soil through their roots to grow. If soil moisture is inadequate, plants fail to grow, which over time can lead to reduced crop yields. Also, energy from the sun evaporates moisture in the soil, thereby cooling surface temperatures and also increasing moisture in the atmosphere, allowing clouds and precipitation to form more readily. In this way, soil moisture has a significant effect on both short-term regional weather and longer-term global climate. In summer, plants in Earths northern boreal regions -- the forests found in Earths high northern latitudes -- take in carbon dioxide from the air and use it to grow, but lay dormant during the winter freeze period. All other factors being equal, the longer the growing season, the more carbon plants take in and the more effective forests are in removing carbon dioxide from the air. Since the start of the growing season is marked by the thawing and refreezing of water in soils, mapping the freeze/thaw state of soils with SMAP will help scientists more accurately account for how much carbon plants are removing from the atmosphere each year. This information will lead to better estimates of the carbon budget in the atmosphere and, hence, better assessments of future global warming. SMAP data will enhance our confidence in projections of how Earths water cycle will respond to climate change. Assessing future changes in regional water availability is perhaps one of the greatest environmental challenges facing the world today. Todays computer models disagree on how the water cycle -- precipitation, clouds, evaporation, runoff, soil water availability -- will increase or decrease over time and in different regions as our world warms. SMAPs higher-resolution soil moisture data will improve the models used to make daily weather and longer-term climate predictions. SMAP also will advance our ability to monitor droughts, predict floods and mitigate the related impacts of these extreme events. It will allow the monitoring of regional deficits in soil moisture and provide critical inputs into drought monitoring and early warning systems used by resource managers. The missions high-resolution observations of soil moisture will improve flood warnings by providing information on ground saturation conditions before rainstorms. SMAPs two advanced instruments work together to produce soil moisture maps. Its active radar works much like a flash camera, but instead of transmitting visible light, it transmits microwave pulses that pass through clouds and moderate vegetation cover to the ground and measures how much of that signal is reflected back. Its passive radiometer operates like a natural-light camera, capturing emitted microwave radiation without transmitting a pulse. Unlike traditional cameras, however, SMAPs images are in the microwave range of the electromagnetic spectrum, which is invisible to the naked eye. Microwave radiation is sensitive to how much moisture is contained in the soil. The two instruments share a large, lightweight reflector antenna that will be unfurled in orbit like a blooming flower and then spin at about 14 revolutions per minute. The antenna will allow the instruments to collect data across a 621-mile (1,000-kilometer) swath, enabling global coverage every two to three days. SMAPs radiometer measurements extend and expand on soil moisture measurements currently made by the European Space Agencys Soil Moisture Ocean Salinity (SMOS) mission, launched in 2009. With the addition of a radar instrument, SMAPs soil moisture measurements will be able to distinguish finer features on the ground. SMAP will launch from Vandenberg Air Force Base on a United Launch Alliance Delta II rocket and maneuver into a 426-mile (685-kilometer) altitude, near-polar orbit that repeats exactly every eight days. The mission is designed to operate at least three years. SMAP is managed for NASAs Science Mission Directorate in Washington by the agency’s Jet Propulsion Laboratory (JPL) in Pasadena, California, with instrument hardware and science contributions made by NASAs Goddard Space Flight Center in Greenbelt, Maryland. JPL is responsible for project management, system engineering, radar instrumentation, mission operations and the ground data system. Goddard is responsible for the radiometer instrument. Both centers collaborate on science data processing and delivery to the Alaska Satellite Facility, in Fairbanks, and the National Snow and Ice Data Center, at the University of Colorado in Boulder, for public distribution and archiving. NASAs Launch Services Program at the agency’s Kennedy Space Center in Florida is responsible for launch management. JPL is managed for NASA by the California Institute of Technology in Pasadena. youtu.be/GCBBEbKVwm4
Posted on: Sun, 25 Jan 2015 04:49:22 +0000
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