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A Radar/Radiometer Instrument for Mapping Soil Moisture and Ocean SalinityThe RadSTAR instrument combines an L-band, digital beam-forming radar with an L-band synthetic aperture, thinned array (STAR) radiometer. The RadSTAR development will support NASA Earth science goals by developing a novel, L-band scatterometer/ radiometer that measures Earth surface bulk material properties (surface emissions and backscatter) as well as surface characteristics (backscatter). Present, real aperture airborne L-Band active/passive measurement systems such as the JPUPALS (Wilson, et al, 2000) provide excellent sampling characteristics, but have no scanning capabilities, and are extremely large; the huge JPUPALS horn requires a the C-130 airborne platform, operated with the aft loading door open during flight operation. The approach used for the upcoming Aquarius ocean salinity mission or the proposed Hydros soil mission use real apertures with multiple fixed beams or scanning beams. For real aperture instruments, there is no upgrade path to scanning over a broad swath, except rotation of the whole aperture, which is an approach with obvious difficulties as aperture size increases. RadSTAR will provide polarimetric scatterometer and radiometer measurements over a wide swath, in a highly space-efficient configuration. The electronic scanning approaches provided through STAR technology and digital beam forming will enable the large L-band aperture to scan efficiently over a very wide swath. RadSTAR technology development, which merges an interferometric radiometer with a digital beam forming scatterometer, is an important step in the path to space for an L-band scatterometer/radiometer. RadSTAR couples a patch array antenna with a 1.26 GHz digital beam forming radar scatterometer and a 1.4 GHz STAR radiometer to provide Earth surface backscatter and emission measurements in a compact, cross-track scanning instrument with no moving parts. This technology will provide the first L-band, emission and backscatter measurements in a compact aircraft instrument and will be ideally suited to large apertures, possibly at GEO, and could possibly be implemented on a swarm of micro-satellites. This instrument will have wide application for validation studies, and will have application for other microwave frequencies.
Document ID
20040021365
Document Type
Preprint (Draft being sent to journal)
Authors
Hildebrand, Peter H. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Hilliard, Laurence (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Rincon, Rafael (NASA Goddard Space Flight Center Greenbelt, MD, United States)
LeVine, David (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Mead, James (ProSensing, Inc. Amherst, MA, United States)
Date Acquired
August 21, 2013
Publication Date
January 1, 2003
Subject Category
Oceanography
Meeting Information
31st Conference on Radar Meteorology(Seattle, WA)
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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