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391.
Alessia De Iuliis Francesco Ciampa Leonard Felicetti Matteo Ceriotti 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2021,67(9):2795-2811
Literature on solar sailing has thus far mostly considered solar radiation pressure (SRP) as the only contribution to sail force. However, considering a sail in a planetary mission scenario, a new contribution can be added. Since the planet itself emits radiation, this generates a radial planetary radiation pressure (PRP) that is also exerted on the sail. Hence, this work studies the combined effects of both SRP and PRP on a sail for two case studies, i.e. Earth and Venus. In proximity of the Earth, the effect of PRP can be significant under specific conditions. Around Venus, instead, PRP is by far the dominating contribution. These combined effects have been studied for single- and double-sided reflective coating and including eclipse. Results show potential increase in the net acceleration and a change in the optimal attitude to maximise the acceleration in a given direction. Moreover, an increasing semi-major axis manoeuvre is shown with and without PRP, to quantify the difference on a real-case scenario. 相似文献
392.
John W. Norbury 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
The Sun undergoes several well known periodicities in activity, such as the Schwabe 11 year cycle, the Gleissberg 80–90 year cycle, the Suess 200–210 year cycle and the Halstatt 2200–2300 year cycle. In addition, there is evidence that the 20th century levels of solar activity are unusually high. The years 2020–2040 are expected to coincide with increased activity in human space flight beyond low Earth orbit. The solar cycles and the present level of solar activity are reviewed and their activities during the years 2020–2040 are discussed with a perspective on space radiation and the future program of space flight. It is prudent to prepare for continuing levels of high solar activity as well as for the low levels of the current deep minimum, which has corresponded to high galactic cosmic ray flux. 相似文献
393.
Michael Meindl Gerhard BeutlerDaniela Thaller Rolf DachAdrian Jäggi 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
Time series of geocenter coordinates were determined with data of two global navigation satellite systems (GNSSs), namely the U.S. GPS (Global Positioning System) and the Russian GLONASS (Global’naya Nawigatsionnaya Sputnikowaya Sistema). The data was recorded in the years 2008–2011 by a global network of 92 permanently observing GPS/GLONASS receivers. Two types of daily solutions were generated independently for each GNSS, one including the estimation of geocenter coordinates and one without these parameters. 相似文献
394.
Salvatore Mancuso Alessandro Bemporad 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2009
We report on the analysis of two fast CME-driven shocks observed with the UltraViolet Coronagraph Spectrometer (UVCS) on board the Solar and Heliospheric Observatory (SOHO). The first event, detected on 2002 March 22 at 4.1 R⊙ with the UVCS slit placed in correspondence with the flank of the expanding CME surface, represents the highest UV detection of a shock obtained so far with the UVCS instrument in the corona. The second one, detected on 2002 July 23 at 1.6 R⊙ with the UVCS slit placed in correspondence with the front of the expanding CME surface, shows an anomalous deficiency of ion heating with respect to what observed in previous CME/shocks observed by UVCS, possibly reflecting the effect of different coronal plasma conditions over the solar cycle. From the two different sets of observations we derived an estimate for the shock compression ratio X, which turns out to be X = 2.4 ± 0.2 and X = 2.2 ± 0.1, respectively, for the first and second event. Comparison between the two events provides complementary perspectives on the dynamical evolution of CME-driven shocks. 相似文献
395.
396.
397.
Ch. Hubaux A.-S. Libert N. Delsate T. Carletti 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
Solar radiation pressure affects the evolution of high area-to-mass geostationary space debris. In this work, we extend the stability study of Valk et al. (2009) by considering the influence of Earth’s shadows on the short- and long-term time evolutions of space debris. To assess the orbits stability, we use the Mean Exponential Growth factor of Nearby Orbits (MEGNO), which is an efficient numerical tool to distinguish between regular and chaotic behaviors. To reliably compute long-term space debris motion, we resort to the Global Symplectic Integrator (GSI) of Libert et al. (2011) which consists in the symplectic integration of both Hamiltonian equations of motion and variational equations. We show how to efficiently compute the MEGNO indicator in a complete symplectic framework, and we also discuss the choice of a symplectic integrator, since propagators adapted to the structure of the Hamiltonian equations of motion are not necessarily suited for the associated variational equations. The performances of our method are illustrated and validated through the study of the Arnold diffusion problem. We then analyze the effects of Earth’s shadows, using the adapted conical and cylindrical Earth’s shadowing models introduced by Hubaux et al. (2012) as the smooth shadow function deriving from these models can be easily included into the variational equations. Our stability study shows that Earth’s shadows greatly affect the global behaviour of space debris orbits by increasing the size of chaotic regions around the geostationary altitude. We also emphasize the differences in the results given by conical or cylindrical Earth’s shadowing models. Finally, such results are compared with a non-symplectic integration scheme. 相似文献
398.
Ts.N. Gogosheva V.N. Grigorieva Ts.T. Evgenieva B.D. Mendeva N.I. Kolev D.G. Krastev B.H. Petkov 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2009
This presentation deals with the recent investigations of the dynamics of the total ozone content (TOC) and of the lower troposphere ozone over Bulgaria, South-Eastern Europe. 相似文献
399.
L. Strachan Y-K. Ko A. V. Panasyuk D. Dobrzycka J. L. Kohl M. Romoli G. Noci S. E. Gibson D. A. Biesecker 《Space Science Reviews》1999,87(1-2):311-314
We constrain coronal outflow velocity solutions, resolved along the line-of-sight, by using Doppler dimming models of H I Lyman alpha and O VI 1032/1037 Å emissivities obtained with data from the Ultraviolet Coronagraph Spectrometer (UVCS) on SOHO. The local emissivities, from heliocentric heights of 1.5 to 3.0 solar radii, were determined from 3-D reconstructions of line-of-sight intensities obtained during the first Whole Sun Month Campaign (10 August to 8 September 1996). The models use electron densities derived from polarized brightness measurements made with the visible light coronagraphs on UVCS and LASCO, supplemented with data from Mark III at NCAR/MLSO. Electron temperature profiles are derived from 'freezing-in' temperatures obtained from an analysis of charge state data from SWICS/Ulysses. The work concentrates on neutral hydrogen outflow velocities which depend on modeling the absolute coronal H I Lyα emissivities. We use an iterative method to determine the neutral hydrogen outflow velocity with consistent values for the electron temperatures derived from a freezing-in model. 相似文献
400.