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 The
Earth's surface is the interface between the atmosphere, hydrosphere,
and the solid Earth and is the interface of greatest importance
to humankind. Imaging spectroscopy (or "hyperspectral”
imaging) can resolve the surface attributes and expression of many
of the processes related to natural and human-induced landscape
change, volcanism, tectonics, and ice dynamics. Because near-surface
materials and their properties often determine a region's
susceptibility to such natural hazards as earthquakes, severe storms,
wildfires, and volcanic activity, characterizing these materials
will contribute significantly to global hazard mapping.
The
power of imaging spectroscopy is the ability for one technique to
provide key data to solve a variety of problems, both within and
outside of solid-Earth science. These data include ones that are
relatively long lasting, such as images of zones of hydrothermally
altered rocks or fault zones, and ones that are rapidly changing,
such as measurements of soil saturation or airborne dust clouds.
High spatial resolution is needed to delineate the persistent, but
spatially complex, features of the Earth's surface, whereas
high temporal resolution is required to predict, track, and mitigate
most natural hazards.
As
the field advances and problems become more specific, imaging spectroscopy
missions must evolve to meet the diverse requirements of a broad
variety of scientific targets. NASA has guided the technique from
the laboratory to airborne experiments and finally to space. Future
spaceborne missions should focus on meeting science-specific requirements
for signal-to-noise ratio, spectral and spatial resolution, and
temporal sampling.
Suggested
mission phasing and requirements
Immediate
(1–5 years): Spaceborne imaging spectrometer
in Visible and Near Infrared (0.2 – 2.5 µm). Airborne
measurements in the thermal infrared (3 – 5 µm and 8
– 14 µm).
Near Term (5–10 years):
Improved spaceborne imaging spectrometer with a 100-km swath and
30-m spatial resolution. Demonstration spaceborne thermal infrared
imaging spectrometer with 30-km swath and 30-m spatial resolution.
Monthly global mapping across visible to thermal wavelengths with
a signal-to-noise ratio > 500.
Long term (10–25 years):
Targeted local to regional mapping, with global access, at 1-m resolution
across multiple wavelengths. Repeat frequency of hours to years
depending on the rate of change of the process being studied.
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