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1.
The PROCESS (PRebiotic Organic ChEmistry on the Space Station) experiment was part of the EXPOSE-E payload outside the European Columbus module of the International Space Station from February 2008 to August 2009. During this interval, organic samples were exposed to space conditions to simulate their evolution in various astrophysical environments. The samples used represent organic species related to the evolution of organic matter on the small bodies of the Solar System (carbonaceous asteroids and comets), the photolysis of methane in the atmosphere of Titan, and the search for organic matter at the surface of Mars. This paper describes the hardware developed for this experiment as well as the results for the glycine solid-phase samples and the gas-phase samples that were used with regard to the atmosphere of Titan. Lessons learned from this experiment are also presented for future low-Earth orbit astrochemistry investigations.  相似文献   
2.
The delivery of extraterrestrial organic materials to primitive Earth from meteorites or micrometeorites has long been postulated to be one of the origins of the prebiotic molecules involved in the subsequent apparition of life. Here, we report on experiments in which vacuum UV photo-irradiation of interstellar/circumstellar ice analogues containing H(2)O, CH(3)OH, and NH(3) led to the production of several molecules of prebiotic interest. These were recovered at room temperature in the semi-refractory, water-soluble residues after evaporation of the ice. In particular, we detected small quantities of hydantoin (2,4-imidazolidinedione), a species suspected to play an important role in the formation of poly- and oligopeptides. In addition, hydantoin is known to form under extraterrestrial, abiotic conditions, since it has been detected, along with various other derivatives, in the soluble part of organic matter of primitive carbonaceous meteorites. This result, together with other related experiments reported recently, points to the potential importance of the photochemistry of interstellar "dirty" ices in the formation of organics in Solar System materials. Such molecules could then have been delivered to the surface of primitive Earth, as well as other telluric (exo-) planets, to help trigger first prebiotic reactions with the capacity to lead to some form of primitive biomolecular activity.  相似文献   
3.
The ultraviolet spectrograph instrument on the Juno mission (Juno-UVS) is a long-slit imaging spectrograph designed to observe and characterize Jupiter’s far-ultraviolet (FUV) auroral emissions. These observations will be coordinated and correlated with those from Juno’s other remote sensing instruments and used to place in situ measurements made by Juno’s particles and fields instruments into a global context, relating the local data with events occurring in more distant regions of Jupiter’s magnetosphere. Juno-UVS is based on a series of imaging FUV spectrographs currently in flight—the two Alice instruments on the Rosetta and New Horizons missions, and the Lyman Alpha Mapping Project on the Lunar Reconnaissance Orbiter mission. However, Juno-UVS has several important modifications, including (1) a scan mirror (for targeting specific auroral features), (2) extensive shielding (for mitigation of electronics and data quality degradation by energetic particles), and (3) a cross delay line microchannel plate detector (for both faster photon counting and improved spatial resolution). This paper describes the science objectives, design, and initial performance of the Juno-UVS.  相似文献   
4.
The European way of doing space differs from others in that, while carried out cooperatively, there is no fully integrated space policy. This is inevitable in a non-sovereign entity whose members do not have the same priorities in many vital sectors such as energy, industry and political economy, and has nevertheless produced some excellent programmes. But, against the background of the worldwide increase in space players and capabilities, Europe's current lack of ambition and foresight, and its limited ability to respond to external developments are worrying. It needs to be more open about its governance and financing plans, something missing from the latest European Commission communication. In these difficult economic times a complete rethinking of future space plans would enable Europe to prioritise on the strategic niches which must be preserved, while proper investigation of the management failures of the flagship programmes might help avoid such difficulties in the future.  相似文献   
5.
Because space-borne radiometers do not measure the Earth’s outgoing fluxes directly, angular distribution models (ADMs) are required to relate actual radiance measurement to flux at given solar angle, satellite-viewing geometries, surface, and atmospheric conditions. The conversion of one footprint broad-band radiance into the corresponding flux requires therefore one to first characterize each footprint in terms of surface type and cloud cover properties to properly select the adequate ADM.

A snow (and sea-ice) retrieval technique based on spectral measurements from the Spinning Enhanced Visible and Infrared Imager (SEVIRI) on board Meteosat 8 is presented. It has been developed to improve the scene identification and thus the ADM selection in the near-real time processing of the Geostationary Earth Radiation Budget (GERB) data at the Royal Meteorological Institute of Belgium. The improvement in the GERB short wave flux estimations over snow covered scene types resulting from angular conversion using dedicated snow ADMs (e.g., empirical snow ADMs and/or pre-computed theoretical snow ADM) instead of empirical snow-free ADMs is discussed.  相似文献   

6.
7.
Zone electrophoresis is a highly efficient method of separating biological products. It is based on the differences of mobilities of ionized particles in an electric field. During the separation complications arise due to electro-osmosis or thermal convection generated by Joule heating.This paper analyses the hydrodynamical running of a continuous flow zone electrophoresis cell and shows the influence of specific parameters on the separation.The modelling of the flow structure of the buffer solution is developed. The equations and the corresponding boundary conditions are solved by finite difference method. The model established provides knowledge of the hydrodynamical perturbations generated by electro-osmosis and thermal free convection. The case of microgravity is considered.  相似文献   
8.
For several years there has been substantial growth in the ‘nationalist’ nature of space programmes around the world, traditionally focused on unaligned useful space applications. It seems that China, India, in the future South Korea, Malaysia and others will set themselves objectives of a more political colouring symbolising national pride in their programmes. At the same time, some countries, like Iran, make no attempt to hide their plans to have their own space defence capabilities. The absolute pre-eminence of the USA, Russia and Europe is starting to fade. For emerging countries space resources are becoming an integral component of their strategic position or an asymmetrical capability aimed at weakening the credibility of advantages held by potential rivals. This article examines the new context and the role that various countries are playing in it. It is how space policies should be determined in order to understand their politico-strategic determinants and to highlight their characteristics. Nevertheless, the competitive spirit is not the only possible way. Permanent space infrastructures could also be organised globally, as ‘global public goods’, to contribute to answering questions related to major issues facing humanity.  相似文献   
9.
To understand the chemical behavior of organic molecules in the space environment, amino acids and a dipeptide in pure form and embedded in meteorite powder were exposed in the PROCESS experiment in the EXPOSE-E facility mounted on the European Technology Exposure Facility (EuTEF) platform on board the International Space Station (ISS). After exposure to space conditions for 18 months, the samples were returned to Earth and analyzed in the laboratory for reactions caused by solar UV and cosmic radiation. Chemical degradation and possible racemization and oligomerization, the main reactions caused by photochemistry in the vacuum ultraviolet domain (VUV, wavelength range 100-200?nm for photon energy from 6.2 to 12.4?eV) were examined in particular. The molecules were extracted and derivatized by silylation and analyzed by gas chromatograph coupled to a mass spectrometer (GC-MS) to quantify the rate of the degradation of the compounds. Laboratory exposure in several wavelength ranges from UV to VUV was carried out in parallel in the Cologne Deutsches Zentrum für Luft- und Raumfahrt (DLR) Center and Centre de biophysique moléculaire (CBM) laboratories. The results show that resistance to irradiation is a function of the chemical nature of the exposed molecules and the wavelengths of the UV light. The most altered compounds were the dipeptide, aspartic acid, and aminobutyric acid. The most resistant were alanine, valine, glycine, and aminoisobutyric acid. Our results also demonstrate the protective effect of meteorite powder, which reemphasizes the importance of exogenic contribution to the inventory of prebiotic organics on early Earth.  相似文献   
10.
The USA adopted a new defence strategy in 2012 which responds to the changing geopolitical landscape and straightened economic circumstances. The emphasis is on leaner, more flexible and diversified operations, while priority areas have shifted from Europe to the Asia-Pacific (in acknowledgement of China's growing military might) and the Middle East. This will have consequences for Europe, which is now expected to take a greater share of the strategic burden. The major developments in the strategy – such as eschewing the pursuit of lengthy engagements on more than one front, and using the military to complement diplomatic and economic initiatives – are discussed. Europe is urged to respond by maintaining its national strategic and industrial autonomy, including in access to space and missile defence.  相似文献   
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