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41.
42.
Stefan Schneider Ryan Robinson Craig Smith Melanie von der Wiesche Nandu Goswami 《Acta Astronautica》2014
Keeping astronauts healthy during long duration spaceflight remains a challenge. Artificial gravity (AG) generated by a short arm human centrifuges (SAHC) is proposed as the next generation of integrated countermeasure devices that will allow human beings to safely spend extended durations in space, although comparatively little is known about any psychological side effects of AG on brain function. 相似文献
43.
Space tourism, private spaceflight and the law: Key aspects 总被引:1,自引:0,他引:1
Frans G. von der Dunk 《Space Policy》2011,27(3):146-152
The arrival of ‘space tourism’, or more appropriately ‘private spaceflight’, requires the law of outer space to change and adapt to this revolutionary development, as deriving precisely from the principled private participation in these activities. After defining the proper concepts, this paper discusses key legal aspects of authorisation and supervision, liability and registration, and how they reflect and impact on space tourism. Key legal aspects related to certification of craft, crew and passengers, while not yet much articulated at the international level will also be touched upon precisely in order to demonstrate that the law could well be driven first and foremost by national legislative interests on a domestic level, before (possibly) reaching the level of international law. The possible use of air law or even adventure tourism law to regulate relevant activities is also touched on. 相似文献
44.
Simultaneous determination of aerosol- and surface characteristics from top-of-atmosphere reflectance using MERIS on board of ENVISAT 总被引:1,自引:0,他引:1
Wolfgang von Hoyningen-Huene Alexander A. Kokhanovsky John P. Burrows Veronique Bruniquel-Pinel Peter Regner Frederic Baret 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2006,37(12):2172-II
The determination of aerosol optical thickness (AOT) from nadir scanning multi-spectral radiometers, like SeaWiFS, MERIS or MODIS, requires the separation of spectral atmospheric and surface properties. Since SeaWiFS and MERIS do not provide information at 2.1 μm, like MODIS, the estimation of the surface reflectance cannot be made by the cross correlation approach described by Kaufman et al., 1997. The BAER approach (Bremen AErosol Retrieval), von Hoyningen-Huene et al., 2003, uses a linear mixing model of spectra for ‘green vegetation’ and ‘bare soil’, tuned by the NDVI, determining an apparent surface to enable this separation of aerosol and surface properties from VIS and NIR channels. Thus AOT can be derived over a wide range of land surfaces for wavelengths <0.67 μm. Using MERIS L1 data over Europe, the AOT retrieved is comparable with ground-based observations, provided by AERONET. Regional variation of AOT can be observed, showing the atmospheric variability for clear sky conditions by: large scale variation of aerosol turbidity, regional pollution, urban regions, effects of contrails and cases of aerosol-cloud interaction. Simultaneously with the spectral AOT also spectral surface reflectance is obtained, where all atmospheric influences have been considered (molecules, aerosols and absorbing gases (O3)) for channels with wavelengths <0.67 μm. The AOT is extrapolated by Angström power law to NIR channels and the atmospheric correction for land surface properties is performed, enabling the further investigation of land use and spectral land properties. 相似文献
45.
R. A. Mewaldt C. M. S. Cohen G. M. Mason A. C. Cummings M. I. Desai R. A. Leske J. Raines E. C. Stone M. E. Wiedenbeck T. T. von Rosenvinge T. H. Zurbuchen 《Space Science Reviews》2007,130(1-4):207-219
Although the average composition of solar energetic particles (SEPs) and the bulk solar wind are similar in a number of ways,
there are key differences which imply that solar wind is not the principal seed population for SEPs accelerated by coronal
mass ejection (CME) driven shocks. This paper reviews these composition differences and considers the composition of other
possible seed populations, including coronal material, impulsive flare material, and interplanetary CME material. 相似文献
46.
H. A. von Biel 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1999,24(12):1669-1677
A short review of the partial reflection experiment is presented along with the commonly made assumptions regarding the scattering mechanisms of the MF magneto-ionic modes in the mesosphere. It is shown that the traditional method of analysing differential absorption data can give rise to considerable errors in the determination of ionisation density at a particular scattering height. A new analysis approach is presented which yields a profile of the product of electron density and collisional frequency, rather than estimates of the electron density only. A by-product of this analysis technique is an estimate of the reflection coefficient factor Fxo(h) which traditionally has been set identically equal to unity. Analysis of data collected from 1983 to 1998 at Scott Base, Antarctica, has revealed that this reflection coefficient factor exhibits a seasonal dependence and differs substantially from unity, particularly at scattering heights between 40km and 60km. It is shown that neglecting this factor could easily lead to the conclusion that differential absorption is present at certain scattering heights with the consequent implication of the presence of ionisation. 相似文献
47.
C.M.S. Cohen R.A. Mewaldt A.C. Cummings R.A. Leske E.C. Stone T.T. von Rosenvinge M.E. Wiedenbeck 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2003,32(12):2649-2654
Using data from the Solar Isotope Spectrometer on the Advanced Composition Explorer obtained during 36large solar energetic particle events (SEPs) that occurred during 1997–2002 we have examined the spectral characteristics of oxygen and iron. Based on the shape of the oxygen spectrum during the decay phase following the peak in particle intensity, each SEP event was categorized as either exponential (7 events) or power law (29 events). We find that the exponential events were typically the larger events (in terms of peak oxygen intensity) and had Fe/0 ratios that strongly decreased with increasing energy.Event-averaged Fe/0 ratios (integrated over 12 to 60 MeV/nucleon) were at or below coronal abundances for nearly all these events, while the ratios obtained in the power law events were typically enhanced over coronal values. The majority of the power law events had the same spectral index for both 0 and Fe resulting in an Fe/0 ratio independent of energy. However 6 of the 29 power law events had Fe/0 ratios that increased with increasing energy due to an Fe spectral index less negative than that of 0. We consider simple diffusion theory in an effort to understand the nature of these events and obtain preliminary but promising results. 相似文献
48.
Europe has begun to face up to the challenges of global satellite navigation. A partial European air navigation service will be implemented, and a strategy for broader involvement in general space-based navigation is being developed. The author examines the nature of positioning systems as providers of a new kind of information commodity, and reflects on possible consequences for the EU's future policy making. 相似文献
49.
Motion sickness can occur when an accelerating force acting on the human body repeatedly changes amplitude and direction or both. It also can occur without any motion after transfer into a constant force field significantly different from Earth-gravity. Dynamic and static causes of motion sickness can be distinguished accordingly. Space sickness, too, has dynamic as well as static aspects. Dynamic space sickness might depend on increased bilateral differential sensitivity of the peripheral and central vestibular apparatus, whereas static space sickness may be caused by erroneous compensation of bilaterial asymmetries of the otolith-system in the microgravity environment. Experiments in airplanes, cars and on a vestibular sled have shown that the susceptibility to motion sickness is highest for changes of acceleration in the negative X-axis (as compared to the other axes) of the body. During reciprocating linear accelerations on the vestibular sled, standstill periods of movement and the direction of movement cannot correctly be indicated, because the peripheral vestibular apparatus lacks true motion detectors. 相似文献
50.
K.H. Fricke U. von Zahn M. Combes Th. Encrenaz 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1981,1(9):165-168
The intensity of the resonantly scattered Ly-α line of the gian planets depends on the scattering column length of atomic hydrogen above the methane layer and on the incident solar flux. We have obtained measurements of the Ly-α brightness of Jupiter and Saturn on December 19, 1979, with a time difference of 111 minutes, which is only slightly longer than the additional travel time for solar photons scattered at Saturn compared to those from Jupiter. This observational technique eliminates two major uncertainties — the use of different instruments and solar variability — affecting previous determinations of the relative brightness of the planets. The measured ratio of the brightness of the subsolar points is 3.0 ± 0.4 which agrees well with the ratio of the incident solar flux of 3.4. This implies approximately equal scattering column lengths of H on both planets. 相似文献