45,156 research outputs found
Visualization of spectral images
Spectral image sensors provide images with a large number of contiguous spectral channels per pixel. Visualization of these huge data sets is not a straightforward issue. There are three principal ways in which spectral data can be presented; as spectra, as image and in feature space. This paper describes several visualization methods and their suitability in the different steps in the research cycle. Combinations of the three presentation methods and dynamic interaction between them, adds significant to the usability. Examples of some software implementations are given. Also the application of volume visualization methods to display spectral images is shown to be valuabl
Earthshine as an Illumination Source at the Moon
Earthshine is the dominant source of natural illumination on the surface of
the Moon during lunar night, and at locations within permanently shadowed
regions that never receive direct sunlight. As such, earthshine may enable the
exploration of areas of the Moon that are hidden from solar illumination. The
heat flux from earthshine may also influence the transport and cold trapping of
volatiles present in the very coldest areas. In this study, Earth's spectral
radiance at the Moon is examined using a suite of Earth spectral models created
using the Virtual Planetary Laboratory (VPL) three dimensional modeling
capability. At the Moon, the broadband, hemispherical irradiance from Earth
near 0 phase is approximately 0.15 watts per square meter, with comparable
contributions from solar reflectance and thermal emission. Over the simulation
timeframe, spanning two lunations, Earth's thermal irradiance changes less than
a few mW per square meter as a result of cloud variability and the
south-to-north motion of sub-observer position. In solar band, Earth's
diurnally averaged light curve at phase angles < 60 degrees is well fit using a
Henyey Greenstein integral phase function. At wavelengths > 0.7 microns, near
the well known vegetation "red edge", Earth's reflected solar radiance shows
significant diurnal modulation as a result of the longitudinal asymmetry in
projected landmass, as well as from the distribution of clouds. A simple
formulation with adjustable coefficients is presented for estimating Earth's
hemispherical irradiance at the Moon as a function of wavelength, phase angle
and sub-observer coordinates. It is demonstrated that earthshine is
sufficiently bright to serve as a natural illumination source for optical
measurements from the lunar surface.Comment: 27 pages, 15 figures, 1 tabl
ASIME 2018 White Paper. In-Space Utilisation of Asteroids: Asteroid Composition -- Answers to Questions from the Asteroid Miners
In keeping with the Luxembourg government's initiative to support the future
use of space resources, ASIME 2018 was held in Belval, Luxembourg on April
16-17, 2018.
The goal of ASIME 2018: Asteroid Intersections with Mine Engineering, was to
focus on asteroid composition for advancing the asteroid in-space resource
utilisation domain. What do we know about asteroid composition from
remote-sensing observations? What are the potential caveats in the
interpretation of Earth-based spectral observations? What are the next steps to
improve our knowledge on asteroid composition by means of ground-based and
space-based observations and asteroid rendez-vous and sample return missions?
How can asteroid mining companies use this knowledge?
ASIME 2018 was a two-day workshop of almost 70 scientists and engineers in
the context of the engineering needs of space missions with in-space asteroid
utilisation. The 21 Questions from the asteroid mining companies were sorted
into the four asteroid science themes: 1) Potential Targets, 2)
Asteroid-Meteorite Links, 3) In-Situ Measurements and 4) Laboratory
Measurements. The Answers to those Questions were provided by the scientists
with their conference presentations and collected by A. Graps or edited
directly into an open-access collaborative Google document or inserted by A.
Graps using additional reference materials. During the ASIME 2018, first day
and second day Wrap-Ups, the answers to the questions were discussed further.
New readers to the asteroid mining topic may find the Conversation boxes and
the Mission Design discussions especially interesting.Comment: Outcome from the ASIME 2018: Asteroid Intersections with Mine
Engineering, Luxembourg. April 16-17, 2018. 65 Pages. arXiv admin note:
substantial text overlap with arXiv:1612.0070
Emission cross sections for energetic O()-N collisions
We report measurements of excitation functions for the ON
process with the incident beam of keV O in the ground
O and metastable O and O states. The
measurements are performed with the sufficiently high energy resolution of
0.001 eV, which allows to distinguish the excitation channels. The excitation
cross section induced by incident ions in the metastable state O
is much larger than that for the ground O. The excitation cross
section of N ion for (0,0), (0,1) and (1,2) bands system is measured
and the ratio of intensities for these bands is established as It is
shown that the cross sections for the Nions excitations in the
dissociative charge exchange processes increase with the increase of the
incident ion energy. The energy dependence of the excitation cross section of
the band (0,0) nm of the first negative system of the
N and degree of polarization of radiation in ON
collision are measured for the first time. An influence of an admixture of the
ion metastable state on a degree of polarization is revealed. It is
demonstrated that for ON collision system the degree of
polarization by metastable O() ions is less compared to those that
are in the ground O() state and the sign of polarization degree of
excited molecular ions does not change.Comment: 15 pages, 8 Figure
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