2,055 research outputs found
Hyperspectral Cubesat Constellation for Rapid Natural Hazard Response
Earth Observing 1 (E0-1) satellite has an imaging spectrometer (hyperspectral) instrument called Hyperion. The satellite is able to image any spot on Earth in the nadir looking direction every 16 days. With slewing of the satellite and allowing for up to a 23 degree view angle, any spot on the Earth can be imaged approximately every 2 to 3 days. EO-1 has been used to track many natural hazards such as wildfires, volcanoes and floods. An enhanced capability that is sought is the ability to image natural hazards in a daily time series for space based imaging spectrometers. The Hyperion can not provide this capability on EO-1 with the present polar orbit. However, a constellation of cubesats, each with the same imaging spectrometer, positioned strategically in the same orbit, can be used to provide daily coverage, cost-effectively
Hyperspectral Cubesat Constellation for Natural Hazard Response (Follow-on)
The authors on this paper are team members of the Earth Observing 1 (E0-1) mission which has flown an imaging spectrometer (hyperspectral) instrument called Hyperion for the past 15+ years. The satellite is able to image any spot on Earth in the nadir looking direction every 16 days and with slewing, of the satellite for up to a 23 degree view angle, any spot on the Earth can be imaged approximately every 2 to 3 days. EO-1 has been used to track many natural hazards such as wildfires, volcanoes and floods. An enhanced capability that has been sought is the ability to image natural hazards in a daily time series for space-based imaging spectrometers. The Hyperion cannot provide this capability on EO-1 with the present polar orbit. However, a constellation of cubesats, each with the same imaging spectrometer, positioned strategically can be used to provide daily coverage or even diurnal coverage, cost-effectively. This paper sought to design a cubesat constellation mission that would accomplish this goal and then to articulate the key tradeoffs
Probing the origin of the dark material on Iapetus
Among the icy satellites of Saturn, Iapetus shows a striking dichotomy
between its leading and trailing hemispheres, the former being significantly
darker than the latter. Thanks to the VIMS imaging spectrometer on-board
Cassini, it is now possible to investigate the spectral features of the
satellites in Saturn system within a wider spectral range and with an enhanced
accuracy than with previously available data. In this work, we present an
application of the G-mode method to the high resolution, visible and near
infrared data of Phoebe, Iapetus and Hyperion collected by Cassini/VIMS, to
search for compositional correlations. We also present the results of a
dynamical study on the efficiency of Iapetus in capturing dust grains
travelling inward in Saturn system to evaluate the viability of
Poynting-Robertson drag as the physical mechanism transferring the dark
material to the satellite. The results of spectroscopic classification are used
jointly with the ones of the dynamical study to describe a plausible physical
scenario for the origin of Iapetus' dichotomy. Our work shows that mass
transfer from the outer Saturnian system is an efficient mechanism,
particularly for the range of sizes hypothesised for the particles composing
the newly discovered outer ring around Saturn. Both spectral and dynamical data
indicate Phoebe as the main source of the dark material. However, we suggest a
multi-source scenario where now extinct prograde satellites and the disruptive
impacts that generated the putative collisional families played a significant
role in supplying the original amount of dark material.Comment: 20 pages, 4 tables, 11 figures, major revision (manuscript extended
and completed, figures added and corrected, new results added), minor
revision and finalization of author list, moderate revision (update of the
manuscript following reviewer's feedback and discovery of the new Saturnian
outer ring
Hyperspectral Cubesat Constellation for Natural Hazard Response (Follow-On)
Earth Observing 1 (E0-1) satellite has an imaging spectrometer (hyperspectral) instrument called Hyperion. The satellite is able to image any spot on Earth in the nadir looking direction every 16 days. With slewing of the satellite and allowing for up to a 23 degree view angle, any spot on the Earth can be imaged approximately every 2 to 3 days. EO-1 has been used to track many natural hazards such as wildfires, volcanoes and floods. An enhanced capability that is sought is the ability to image natural hazards in a daily time series for space based imaging spectrometers. The Hyperion can not provide this capability on EO-1 with the present polar orbit. However, a constellation of cubesats each powered with Intelligent Payload Modules, and each with copies of a commercial imaging spectrometer, positioned strategically in the same orbit, can be used to provide daily coverage, cost-effectively
Canopy nitrogen, carbon assimilation, and albedo in temperate and boreal forests: Functional relations and potential climate feedbacks
The availability of nitrogen represents a key constraint on carbon cycling in terrestrial ecosystems, and it is largely in this capacity that the role of N in the Earth\u27s climate system has been considered. Despite this, few studies have included continuous variation in plant N status as a driver of broad-scale carbon cycle analyses. This is partly because of uncertainties in how leaf-level physiological relationships scale to whole ecosystems and because methods for regional to continental detection of plant N concentrations have yet to be developed. Here, we show that ecosystem CO2 uptake capacity in temperate and boreal forests scales directly with whole-canopy N concentrations, mirroring a leaf-level trend that has been observed for woody plants worldwide. We further show that both CO2 uptake capacity and canopy N concentration are strongly and positively correlated with shortwave surface albedo. These results suggest that N plays an additional, and overlooked, role in the climate system via its influence on vegetation reflectivity and shortwave surface energy exchange. We also demonstrate that much of the spatial variation in canopy N can be detected by using broad-band satellite sensors, offering a means through which these findings can be applied toward improved application of coupled carbon cycleâclimate models
A Search for Water Masers in the Saturnian System
We searched for H2O 6(1,6)-5(2,3) maser emission at 22.235 GHz from several
Saturnian satellites with the Nobeyama 45m radio telescope in May 2009.
Observations were made for Titan, Hyperion, Enceladus and Atlas, for which
Pogrebenko et al. (2009) had reported detections of water masers at 22.235 GHz,
and in addition for Iapetus and other inner satellites. We detected no emission
of the water maser line for all the satellites observed, although sensitivities
of our observations were comparable or even better than those of Pogrebenko et
al.. We infer that the water maser emission from the Saturnian system is
extremely weak, or sporadic in nature. Monitoring over a long period and
obtaining statistical results must be made for the further understanding of the
water maser emission in the Saturnian system.Comment: 8 pages, 2 figures, accepted for publication in PASJ (Letter
Contribution of leaf specular reflection to canopy reflectance under black soil case using stochastic radiative transfer model
Numerous canopy radiative transfer models have been proposed based on the assumption of âideal bi-Lambertian leavesâ with the aim of simplifying the interactions between photons and vegetation canopies. This assumption may cause discrepancy between the simulated and measured canopy bidirectional reflectance factor (BRF). Few studies have been devoted to evaluate the impacts of such assumption on simulation of canopy BRF at a high-to-medium spatial resolution (âŒ30âm). This paper focuses on quantifying the contribution of leaf specular reflection on the estimation of canopy BRF under a black soil case using one of the most efficient radiative transfer models, the stochastic radiative transfer model. Analyses of field and satellite data collected over the boreal HyytiĂ€lĂ€ forest in Finland show that leaf specular reflection may lead to errors of up to 33.1% at 550ânm and 32.8% at 650ânm in terms of relative root mean square error. The results suggest that, in order to minimize these errors, leaf specular reflection should be accounted for in modeling BRF.This research was supported by the Fundamental Research Funds for the Central Universities under Grant No. 531107051063 and Guangxi Natural Science Foundation under Grant No. 2016JJD110017. We would like to thank Dr. Rautiainen Miina and Mottus Matti for sharing the field data and the USGS for making the EO-1 Hyperion hyperspectral data publically available. (531107051063 - Fundamental Research Funds for the Central Universities; 2016JJD110017 - Guangxi Natural Science Foundation)Accepted manuscrip
Space-based remote imaging spectroscopy of the Aliso Canyon CH_4 superemitter
The Aliso Canyon gas storage facility near Porter Ranch, California, produced a large accidental CH_4 release from October 2015 to February 2016. The Hyperion imaging spectrometer on board the EO-1 satellite successfully detected this event, achieving the first orbital attribution of CH_4 to a single anthropogenic superemitter. Hyperion measured shortwave infrared signatures of CH_4 near 2.3 ÎŒm at 0.01 ÎŒm spectral resolution and 30 m spatial resolution. It detected the plume on three overpasses, mapping its magnitude and morphology. These orbital observations were consistent with measurements by airborne instruments. We evaluate Hyperion instrument performance, draw implications for future orbital instruments, and extrapolate the potential for a global survey of CH_4 superemitters
Quality criteria benchmark for hyperspectral imagery
Hyperspectral data appear to be of a growing interest
over the past few years. However, applications for hyperspectral
data are still in their infancy as handling the significant size of
the data presents a challenge for the user community. Efficient
compression techniques are required, and lossy compression,
specifically, will have a role to play, provided its impact on remote
sensing applications remains insignificant. To assess the data
quality, suitable distortion measures relevant to end-user applications
are required. Quality criteria are also of a major interest
for the conception and development of new sensors to define their
requirements and specifications. This paper proposes a method to
evaluate quality criteria in the context of hyperspectral images.
The purpose is to provide quality criteria relevant to the impact
of degradations on several classification applications. Different
quality criteria are considered. Some are traditionnally used in
image and video coding and are adapted here to hyperspectral
images. Others are specific to hyperspectral data.We also propose
the adaptation of two advanced criteria in the presence of different
simulated degradations on AVIRIS hyperspectral images. Finally,
five criteria are selected to give an accurate representation of the
nature and the level of the degradation affecting hyperspectral
data
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