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3.0 CURRENT AIRCRAFT SAR SYSTEMS
3.1 Goodyear Aerospace X-Band Synthetic Aperture
Radar
Large areas of South America, notably Columbia,
Venezuela and Brazil and in the Asian Pacific region were
fown in the 1970's and 1980's by Goodyear
Aerospace/Litton Aeroservice using a Caravelle Jet
platform and a version of a military reconnaissance radar.
This radar was an X-band (3cm wavelength system) which
provided about 10 meter spatial resolution over
approximately a 10km swath. Normally, swaths of
coverage were mosaiced together to provide quadrangle
coverage. Litton Aeroservice no longer provides this
service because of the proliferation of spaceborne radar
systems.
3.2 Motorola-MARS X-Band Real Aperture System
During the 1980's Motorola-MARS provided X-band radar
data from an AN/APQ-94 reconnaissance radar system
mounted in a Mohawk aircraft. This system has acquired
data in Africa and in Indonesia however no new data are
currently being acquired.
3.3 Intera SAR System (STAR-1)
Intera currently operates the only airborne SAR system
available for commercial surveys worldwide. Its STAR-1
system consists of an X-band (3cm wavelength) synthetic
aperature radar which operates in two modes: 6 meter
GIFOV with 23 km swath and 12 meter GIFOV with 46 km
swath. Intera has acquired over 50 million square
kilometers of data worldwide, a significant part of which is
for geological mapping and mineral exploration.
3.4 ERIM Multiband SAR System
Currently, the Environmental Research Institute of
Michigan is flying a multiband SAR System which also has
the capability of acquiring interferometric SAR data. The
system simultaneously acquires X, C and L-band data at
10 meter spatial resolution using a Convair 550 platform.
4.0 ADVANCED IMAGING SYSTEMS
4.1 Jet Propulsion Laboratory AIS and AVIRIS
Beginning in the early 1980's NASA and the Jet Propulsion
Laboratory began to develop the first hyperspectral
imagers. In 1982, Dr. A. F. H. Goetz, using Director's
development funds at the Jet Propulsion Laboratory,
developed the first Airborne Imaging Spectrometer (AIS).
That instrument was first flown over the Cuprite area near
Goldfield, Nevada, and analysis of its data clearly
demonstrated not only could mineral species be
discriminated by remote sensing techniques, they could be
uniquely identified. The AIS was followed by an Airborne
Visible and Infrared Imaging Spectrometer (AVIRIS) which
moved hyperspectral imaging from the breadboard stage
to an operational stage. AVIRIS has 220 bands with 9.6nm
bandwidths covering the spectral interval from 410nm to
2450nm. AVIRIS was flown at an altitutde of 20km in a U-
2aircraft and from that height it produced 20 meter pixels
over an 11km by 11km area. In 1994 and 1995 AVIRIS
691
data over Cuprite were analyzed by the U. S. Geological
Survey and they found that different temperatures of
alunite formation could be discriminated. NASA is
considering mounting AVIRIS in a C-130 aircraft to provide
5 to 10 meter spatial resolution. In 1995 the signal to noise
in the instrument was significantly improved to over 300 to
1:
4.2 NASA TIMS
NASA Developed a Thermal Infrared Multispectral Scanner
(TIMS) in the early 1980's. The instrument was developed
by the Jet Propulsion Laboratory and has been flown on
Lear Jet and C-130 platforms by NASA Stennis Space
Center and NASA Ames Research Center. TIMS uses six
spectral bands in the 8000 to 12000nm portion of the long-
wave thermal infrared spectrum. The bandpasses range
from 400nm to 1000nm and the Noise Equivalent
Temperature Difference (NEDT) ranges from 0.01 degree
Kelvin to 0.3 degree Kelvin at the longer wavelengths.
TIMS overflights are supported by ground-based thermal
emission spectrometers developed by NASA and
Geophysical Environmental Research.
4.3 Geophysical Environmental Research Imaging
Spectrometer (GERIS)
In 1986, Geophysical Environmental Research (GER)
began flying a 63-band hyperspectral imager called
GERIS. The system utilized an optical-mechanical
scanning approach and three spectrometers to cover the
solar spectrum from 430 to 2500 nanometers. The first 25
bands had bandwidths of 25 nanometers, the second 7
bands had bandwidths of 120 nanometers and the last 31
bands had bandwidths of 16 nanometers. At a flight height
above terrain of 4000 meters it had an 8000 meter swath
and collected data from 16 meter ground instantaneous
field of view (GIFOV). Because of its high signal-to-noise
it became the commercial hyperspectral remote sensing
instrument of choice by most of the mineral exploration
companies in the western United States.
4.4 GER Environmental Probe Sensor Series
Geophysical Environmental Research has developed a
number of advanced imaging systems as environmental
probes. The EPS A Series are a 32 channel systems with
28 channels in the VIS/NIR and 2 channels in the SWIR
(1.6 and 2.2um) and 2 channels in the thermal infrared (3-
Sun and 8-14um). The GER-DAIS 3715 is different than
the EPS-A in that it has 37 channels with 32 in the VIS and
3 in the SWIR.
4.5 GER DAIS 7915
The Geophysical Environmental Research GER DAIS 7915
has 79 possible spectral band combinations. The VIS/NIR
spectral bands range from 498nm to 1010nm with 16nm
bandwidths (32 spectral bands). The SWIR-1 has 8 bands
with 100nm bandwidths over a spectral interval of 1000nm
to 1800nm. The SWIR-2 has 31 bands with 15nm
bandwidths over a spectral interval of 1970nm to 2450nm.
There is one band in the 3um to bum region with a 2000nm
bandpass and six bands in the 8um to 12.3um region with
600nm bandpasses. The swath is 5km at 3000 meter AGL
and the spatial resolution is 10 meters at the same altitude.
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B7. Vienna 1996
