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1995-02-23
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PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIFORNIA 91109. TELEPHONE (818) 354-5011
PHOTO CAPTION P-43932
April 18, 1994
Kilauea X, C & L/3-D
This is a three-dimensional perspective view of a false-color
image of the eastern part of the Big Island of Hawaii. It was
produced using all three radar frequencies -- X-band, C-band and
L-band -- from the Spaceborne Imaging Radar-C/X-Band Synthetic
Aperture Radar (SIR-C/X-SAR) flying on the space shuttle
Endeavour, overlaid on a U.S. Geological Survey digital elevation
map. Visible in the center of the image in blue are the summit
crater (Kilauea Caldera) which contains the smaller Halemaumau
Crater, and the line of collapse craters below them that form the
Chain of Craters Road. The image was acquired on April 12, 1994
during orbit 52 of the space shuttle. The area shown is
approximately 34 by 57 kilometers (21 by 35 miles) with the top
of the image pointing toward northwest. The image is centered at
about 155.25 degrees west longitude and 19.5 degrees north
latitude. The false colors are created by displaying three radar
channels of different frequency. Red areas correspond to high
backscatter at L-HV polarization, while green areas exhibit high
backscatter at C-HV polarization. Finally blue shows high return
at X-VV polarization. Using this color scheme, the rain forest
appears bright on the image, while the green areas correspond to
lower vegetation. The lava flows have different colors depending
on their types and are easily recognizable due to their shapes.
The flows at the top of the image originated from the Mauna Loa
volcano. Kilauea volcano has been almost continuously active for
more than the last 11 years. Field teams that were on the ground
specifically to support these radar observations report that
there was vigorous surface activity about 400 meters (one-quarter
mile) inland from the coast. A moving lava flow about 200 meters
(650 feet) in length was observed at the time of the shuttle
overflight, raising the possibility that subsequent images taken
during this mission will show changes in the landscape.
Currently, most of the lava that is erupted travels the 8
kilometers (5 miles) from the Pu'u O'o crater (the active vent)
just outside this image to the coast through a series of lava
tubes, but in the past there have been many large lava flows that
have traveled this distance, destroying houses and parts of the
Hawaii Volcanoes National Park. This SIR-C/X-SAR image shows two
types of lava flows that are common to Hawaiian volcanoes.
Pahoehoe lava flows are relatively smooth, and appear very dark
blue because much of the radar energy is reflected away from the
radar. In contrast other lava flows are relatively rough and
bounce much of the radar energy back to the radar, making that
part of the image bright blue. This radar image is valuable
because it allows scientists to study an evolving lava flow field
from the Pu'u O'o vent. Much of the area on the northeast side
(right) of the volcano is covered with tropical rain forest, and
because trees reflect a lot of the radar energy, the forest
appears bright in this radar scene. The linear feature running
from Kilauea Crater to the right of the image is Highway 11
leading to the city of Hilo which is located just beyond the
right edge of this image.
-----
Spaceborne Imaging Radar-C and X-Synthetic Aperture Radar
(SIR-C/X-SAR) is part of NASA's Mission to Planet Earth. The
radars illuminate Earth with microwaves allowing detailed
observations at any time, regardless of weather or sunlight
conditions. SIR-C/X-SAR uses three microwave wavelengths: L-band
(24 cm), C-band (6 cm) and X-band (3 cm). The multi-frequency
data will be used by the international scientific community to
better understand the global environment and how it is changing.
The SIR-C/X-SAR data, complemented by aircraft and ground
studies, will give scientists clearer insights into those
environmental changes which are caused by nature and those
changes which are induced by human activity. SIR-C was developed
by NASA's Jet Propulsion Laboratory. X-SAR was developed by the
Dornier and Alenia Spazio companies for the German space agency,
Deutsche Agentur fuer Raumfahrtangelegenheiten (DARA), and the
Italian space agency, Agenzia Spaziale Italiana (ASI), with the
Deutsche Forschungsanstalt fuer Luft und Raumfahrt e.v. (DLR),
the major partner in science, operations and data processing of
X-SAR.
#####