The Soil Moisture Active Passive ( SMAP ) Mission This paper describes an instrument designed to distinguish frozen from thawed land surfaces from an Earth satellite by bouncing signals back to Earth from deployable mesh antennas

| The Soil Moisture Active Passive (SMAP) mission is one of the first Earth observation satellites being developed by NASA in response to the National Research Council’s Decadal Survey. SMAP will make global measurements of the soil moisture present at the Earth’s land surface and will distinguish frozen from thawed land surfaces. Direct observations of soil moisture and freeze/thaw state from space will allow significantly improved estimates of water, energy, and carbon transfers between the land and the atmosphere. The accuracy of numerical models of the atmosphere used in weather prediction and climate projections are critically dependent on the correct characterization of these transfers. Soil moisture measurements are also directly applicable to flood assessment and drought monitoring. SMAP observations can help monitor these natural hazards, resulting in potentially great economic and social benefits. SMAP observations of soil moisture and freeze/thaw timing will also reduce a major uncertainty in quantifying the global carbon balance by helping to resolve an apparent missing carbon sink on land over the boreal latitudes. The SMAP mission concept will utilize L-band radar and radiometer instruments sharing a rotating 6-m mesh reflector antenna to provide highresolution and high-accuracy global maps of soil moisture and freeze/thaw state every two to three days. In addition, the SMAP project will use these observations with advanced modeling and data assimilation to provide deeper root-zone soil moisture and net ecosystem exchange of carbon. SMAP is scheduled for launch in the 2014–2015 time frame.

[1]  P. Strevens Iii , 1985 .

[2]  Thomas J. Jackson,et al.  Passive microwave remote sensing of soil moisture: results from HAPEX, FIFE and MONSOON 90 , 1992 .

[3]  Thomas J. Jackson,et al.  Soil moisture and rainfall estimation over a semiarid environment with the ESTAR microwave radiometer , 1993, IEEE Trans. Geosci. Remote. Sens..

[4]  Jiancheng Shi,et al.  The Soil Moisture Active Passive (SMAP) Mission , 2010, Proceedings of the IEEE.

[5]  Pascale C. Dubois,et al.  Measuring soil moisture with imaging radars , 1995, IEEE Trans. Geosci. Remote. Sens..

[6]  Richard K. Moore,et al.  Radar remote sensing and surface scattering and emission theory , 1986 .

[7]  T. Schmugge,et al.  Vegetation effects on the microwave emission of soils , 1991 .

[8]  Jeffrey Piepmeier,et al.  Mitigation of Terrestrial Radar Interference in L-Band Spaceborne Microwave Radiometers , 2006, 2006 IEEE International Symposium on Geoscience and Remote Sensing.

[9]  Sidharth Misra,et al.  RFI detection and mitigation for microwave radiometry with an agile digital detector , 2006, IEEE Transactions on Geoscience and Remote Sensing.

[10]  W. Marsden I and J , 2012 .

[11]  Thomas J. Jackson,et al.  Soil moisture mapping at regional scales using microwave radiometry: the Southern Great Plains Hydrology Experiment , 1999, IEEE Trans. Geosci. Remote. Sens..

[12]  Thomas J. Jackson,et al.  Observations of soil moisture using a passive and active low-frequency microwave airborne sensor during SGP99 , 2002, IEEE Trans. Geosci. Remote. Sens..

[13]  Yann Kerr,et al.  The SMOS Mission: New Tool for Monitoring Key Elements ofthe Global Water Cycle , 2010, Proceedings of the IEEE.

[14]  T. Jackson,et al.  L‐band microwave observations over land surface using a two‐dimensional synthetic aperture radiometer , 2006 .

[15]  R. Stephenson A and V , 1962, The British journal of ophthalmology.

[16]  Richard K. Moore,et al.  Microwave Remote Sensing, Active and Passive , 1982 .

[17]  C. Swift,et al.  Microwave remote sensing , 1980, IEEE Antennas and Propagation Society Newsletter.

[18]  Yann Kerr,et al.  SMOS: The Challenging Sea Surface Salinity Measurement From Space , 2010, Proceedings of the IEEE.

[19]  Thomas J. Schmugge,et al.  Remote Sensing of Soil Moisture with Microwave Radiometers , 1983 .

[20]  Thomas J. Jackson,et al.  Skylab L band microwave radiometer observations of soil moisture revisited , 2002, IEEE International Geoscience and Remote Sensing Symposium.

[21]  Adriano Camps,et al.  A Change Detection Algorithm for Retrieving High-Resolution Soil Moisture From SMAP Radar and Radiometer Observations , 2009, IEEE Transactions on Geoscience and Remote Sensing.

[22]  Venkat Lakshmi,et al.  A simple algorithm for spatial disaggregation of radiometer derived soil moisture using higher resolution radar observations , 2004, IGARSS 2004. 2004 IEEE International Geoscience and Remote Sensing Symposium.

[23]  R. Reichle Data assimilation methods in the Earth sciences , 2008 .

[24]  Thomas Schmugge,et al.  Passive Microwave Soil Moisture Research , 1986, IEEE Transactions on Geoscience and Remote Sensing.

[25]  Joel T. Johnson,et al.  Airborne radio-frequency interference studies at C-band using a digital receiver , 2006, IEEE Trans. Geosci. Remote. Sens..

[26]  F. Ulaby,et al.  Radar mapping of surface soil moisture , 1996 .

[27]  Thomas J. Jackson,et al.  Combined Passive and Active Soil Moisture Observations During Clasic , 2008, IGARSS 2008 - 2008 IEEE International Geoscience and Remote Sensing Symposium.

[28]  Yann Kerr,et al.  A Simple Model of the Bare Soil Microwave Emission at L-Band , 2007, IEEE Transactions on Geoscience and Remote Sensing.

[29]  E. Njoku,et al.  Passive microwave remote sensing of soil moisture , 1996 .

[30]  Jiancheng Shi,et al.  Estimation of bare surface soil moisture and surface roughness parameter using L-band SAR image data , 1997, IEEE Trans. Geosci. Remote. Sens..