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21.
Chae Kyung Sim Huynh Anh Nguyen Le Soojong Pak Hye-In Lee Wonseok Kang Moo-Young Chun Ueejeong Jeong In-Soo Yuk Kang-Min Kim Chan Park Michael D. Pavel Daniel T. Jaffe 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
We present a Python-based data reduction pipeline package (PLP) for the Immersion GRating INfrared Spectrograph (IGRINS), an instrument that covers the complete H- and K-bands in one exposure with a spectral resolving power of 40,000. The reduction steps carried out by the PLP include flat-fielding, background removal, order extraction, distortion correction, wavelength calibration, and telluric correction using spectra of A type standard stars. As the spectrograph has no moving parts, the PLP automatically reduces the data using predefined functions for the processes of order extraction, distortion correction, and wavelength calibration. Before the telluric correction of the target spectra, the intrinsic hydrogen absorption features of the standard A star are removed with a Gaussian fitting algorithm. The final result is the flux of the target as a function of wavelength. Users can customize the predefined functions for the extraction of the spectrum from the echellogram and adjust the parameters for the fitting functions for the spectra of celestial objects, using “fine-tuning” options, as necessary. Presently, the PLP produces the best results for point-source targets. 相似文献
22.
Frédérique Seyler Stéphane Calmant Joecila Santos da Silva Daniel Medeiros Moreira Franck Mercier C.K. Shum 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
A major interest of radar altimetry over rivers is to monitor water resources and associated risk in basins where there is little or no conventional in situ data. The objective of the present study is to calibrate altimetry data in a place where conventional data are available, and use the results to estimate the potential error committed in the estimation of water levels in an ungauged or poorly gauged basin. The virtual stations extracted with Jason-2 in this study concern a very broad sample of river channel width and complexity. Minimum channel width has been estimated at 400 m. Unlike TOPEX/Poseidon (T/P), Jason-2 seems to have the capability to distinguish the river bed from its floodplain. The quality of the results obtained with Jason-2 is incomparably better than that obtained with T/P. Despite the fact that no absolute calibration has been assessed for river in this study, the bias calculated converge around 0, 35 m, which could be then the error estimated on the water stage derived from Jason-2 ranges, when no other validation is available. ICE3 algorithm seems to be performing as well as ICE1, and further research is needed to design retracking algorithm specifically for continental water. 相似文献
23.
Radiation protective structures on the base of a case study for a manned Mars mission 总被引:1,自引:0,他引:1
Plans for interplanetary manned space missions imply significant risks arising from human's exposure to the hostile space environment. Thus the design of reliable protection systems against the ionizing cosmic radiation becomes one of the most relevant issues. In this paper the composition and magnitude of the atmospheric radiation on the planetary surface and for typical interplanetary transfer configurations have been analyzed. The investigation based on prior NASA and ESA mission results, using a manned mission to planet Mars as a case study. According to this, the time-dependent character of the consistency of cosmic radiation has been taken into account, which is justified by the interdependence of the radiation magnitude to the solar cycle. With regard to this paper it implies even solar particle events. The results have been compared to the protective character of different materials potentially usable as a habitat's structural shell and for interplanetary spacecrafts. The investigation aimed on particle energy degradation rates and reduction of secondary particle production. In this regard the physical process of absorbing effectiveness against particle radiation has been examined by analytical calculation and given scientific results, depending on thickness and molecular composition of the materials. The most suitable materials have been used for shield design proposals using different configurations, evaluating the use of aluminium, water tanks and polyethylene bricks. 相似文献
24.
Rob R. Landis Paul A. Abell David J. Korsmeyer Thomas D. Jones Daniel R. Adamo 《Acta Astronautica》2009,65(11-12):1689-1697
In late 2006, NASA's Constellation Program sponsored a study to examine the feasibility of sending a piloted Orion spacecraft to a near-Earth object. NEOs are asteroids or comets that have perihelion distances less than or equal to 1.3 astronomical units, and can have orbits that cross that of the Earth. Therefore, the most suitable targets for the Orion Crew Exploration Vehicle (CEV) are those NEOs in heliocentric orbits similar to Earth's (i.e. low inclination and low eccentricity). One of the significant advantages of this type of mission is that it strengthens and validates the foundational infrastructure of the United States Space Exploration Policy and is highly complementary to NASA's planned lunar sortie and outpost missions circa 2020. A human expedition to a NEO would not only underline the broad utility of the Orion CEV and Ares launch systems, but would also be the first human expedition to an interplanetary body beyond the Earth–Moon system. These deep space operations will present unique challenges not present in lunar missions for the onboard crew, spacecraft systems, and mission control team. Executing several piloted NEO missions will enable NASA to gain crucial deep space operational experience, which will be necessary prerequisites for the eventual human missions to Mars.Our NEO team will present and discuss the following:
- • new mission trajectories and concepts;
- • operational command and control considerations;
- • expected science, operational, resource utilization, and impact mitigation returns; and
- • continued exploration momentum and future Mars exploration benefits.
Keywords: NASA; Human spaceflight; NEO; Near-Earth asteroid; Orion spacecraft; Constellation program; Deep space 相似文献
25.
Daniel Matthiä Thomas BergerGünther Reitz 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
Humans in space are exposed to elevated levels of radiation compared to ground. Different sources contribute to the total exposure with galactic cosmic rays being the most important component. The application of numerical and anthropomorphic phantoms in simulations allows the estimation of dose rates from galactic cosmic rays in individual organs and whole body quantities such as the effective dose. The male and female reference phantoms defined by the International Commission on Radiological Protection and the hermaphrodite numerical RANDO phantom are voxel implementations of anthropomorphic phantoms and contain all organs relevant for radiation risk assessment. These anthropomorphic phantoms together with a spherical water phantom were used in this work to translate the mean shielding of organs in the different anthropomorphic voxel phantoms into positions in the spherical phantom. This relation allows using a water sphere as surrogate for the anthropomorphic phantoms in both simulations and measurements. Moreover, using spherical phantoms in the calculation of radiation exposure offers great advantages over anthropomorphic phantoms in terms of computational time. 相似文献
26.
Alankrita Isha Mrigakshi Daniel Matthiä Thomas Berger Günther Reitz Robert F. Wimmer-Schweingruber 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
The radiation environment in space is a major concern for human spaceflight because of the adverse effects of high levels of radiation on astronauts’ health. Therefore, it is essential to perform radiation risk assessments already during the concept studies of a manned mission. Galactic Cosmic Rays (GCR) have been identified to be one of the primary sources of radiation exposure in space. 相似文献
27.
Francis F. Badavi Daniel O. Adams John W. Wilson 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2010
The origin of the aluminum equivalent shield approximation in space radiation analysis can be traced back to its roots in the early years of the NASA space programs (Mercury, Gemini and Apollo) wherein the primary radiobiological concern was the intense sources of ionizing radiation causing short term effects which was thought to jeopardize the safety of the crew and hence the mission. Herein, it is shown that the aluminum equivalent shield approximation, although reasonably well suited for that time period and to the application for which it was developed, is of questionable usefulness to the radiobiological concerns of routine space operations of the 21st century which will include long stays onboard the International Space Station (ISS) and perhaps the moon. This is especially true for a risk based protection system, as appears imminent for deep space exploration where the long-term effects of Galactic Cosmic Ray (GCR) exposure is of primary concern. The present analysis demonstrates that sufficiently large errors in the interior particle environment of a spacecraft result from the use of the aluminum equivalent approximation, and such approximations should be avoided in future astronaut risk estimates. In this study, the aluminum equivalent approximation is evaluated as a means for estimating the particle environment within a spacecraft structure induced by the GCR radiation field. For comparison, the two extremes of the GCR environment, the 1977 solar minimum and the 2001 solar maximum, are considered. These environments are coupled to the Langley Research Center (LaRC) deterministic ionized particle transport code High charge (Z) and Energy TRaNsport (HZETRN), which propagates the GCR spectra for elements with charges (Z) in the range 1 ? Z ? 28 (H–Ni) and secondary neutrons through selected target materials. The coupling of the GCR extremes to HZETRN allows for the examination of the induced environment within the interior of an idealized spacecraft as approximated by a spherical shell shield, and the effects of the aluminum equivalent approximation for a good polymeric shield material such as generic polyethylene (PE). The shield thickness is represented by a 25 g/cm2 spherical shell. Although, one could imagine the progression to greater thickness, the current range will be sufficient to evaluate the qualitative usefulness of the aluminum equivalent approximation. Upon establishing the inaccuracies of the aluminum equivalent approximation through numerical simulations of the GCR radiation field attenuation for PE and aluminum equivalent PE spherical shells, we further present results for a limited set of commercially available, hydrogen rich, multifunctional polymeric constituents to assess the effect of the aluminum equivalent approximation on their radiation attenuation response as compared to the generic PE. 相似文献
28.
Where's Downtown?: Behavioral Methods for Determining Referents of Vague Spatial Queries 总被引:1,自引:0,他引:1
Daniel R. Montello Michael F. Goodchild Jonathon Gottsegen Peter Fohl 《Spatial Cognition & Computation》2013,13(2-3):185-204
Humans think and talk about regions and spatial relations imprecisely, in terms of vague concepts that are fuzzy or probabilistic (e.g., downtown, near). The functionality of geographic information systems will be increased if they can interpret vague queries. We discuss traditional and newer approaches to defining and modeling spatial queries. Most of the research on vague concepts in information systems has focussed on mathematical and computational implementation. To complement this, we discuss behavioral-science methods for determining the referents of vague spatial terms, particularly vague regions. We present a study of the empirical determination of downtown Santa Barbara. We conclude with a discussion of prospects and problems for integrating vague concepts into geographic information systems. 相似文献
29.
Martin Tluczykont Daniel Hampf Dieter Horns Tanja Kneiske Robert Eichler Rayk Nachtigall Gavin Rowell 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
The question of the origin of cosmic rays and other questions of astroparticle and particle physics can be addressed with indirect air-shower observations above 10 TeV primary energy. We propose to explore the cosmic ray and γ-ray sky (accelerator sky) in the energy range from 10 TeV to 1 EeV with the new ground-based large-area wide angle (ΔΩ ∼ 0.85 sterad) air-shower detector HiSCORE (Hundred∗i Square-km Cosmic ORigin Explorer). The HiSCORE detector is based on non-imaging air-shower Cherenkov light-front sampling using an array of light-collecting stations. A full detector simulation and basic reconstruction algorithms have been used to assess the performance of HiSCORE. First prototype studies for different hardware components of the detector array have been carried out. The resulting sensitivity of HiSCORE to γ-rays will be comparable to CTA at 50 TeV and will extend the sensitive energy range for γ-rays up to the PeV regime. HiSCORE will also be sensitive to charged cosmic rays between 100 TeV and 1 EeV. 相似文献
30.
Alankrita Isha Mrigakshi Daniel Matthiä Thomas Berger Günther Reitz Robert F. Wimmer-Schweingruber 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
The evidently low solar activity observed between solar cycles 23 and 24 during the years 2008–2010 led to a substantial increase in the Galactic Cosmic Ray (GCR) intensity in comparison with preceding solar minima. As the GCRs consist of highly-ionizing charged particles having the potential to cause biological damage, they are a subject of concern for manned missions to space. With the enhanced particle fluxes observed between 2008 and 2010, it is reasonable to assume that the radiation exposure from GCR must have also increased to unusually high levels. In this paper, the GCR exposure outside and inside the Earth’s magnetosphere is numerically calculated for time periods starting from 1970 to the end of 2011 in order to investigate the increase in dose levels during the years 2008–2010 in comparison with the last three solar minima. The dose rates were calculated in a water sphere, used as a surrogate for the human body, either unshielded or surrounded by aluminium shielding of 0.3, 10 or 40 g/cm2. 相似文献