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991.
Ivanova TN Kostov PT Sapunova SM Dandolov IW Salisbury FB Bingham GE Sytchov VN Levinskikh MA Podolski IG Bubenheim DB Jahns G 《Acta Astronautica》1998,42(1-8):11-23
SVET Space Greenhouse (SG)--the first automated facility for growing of higher plants in microgravity was designed in the eighty years to be used for the future BLSS. The first successful experiment with vegetables was carried out in 1990 on the MIR Space Station (SS). The experiments in SVET SG were resumed in 1995, when an American Gas Exchange Measurement System (GEMS) was added. A three-month wheat experiment was carried out as part of MIR-SHUTTLE'95 program. SVET-2 SG Bulgarian equipment of a new generation with optimised characteristics was developed (financed by NASA). The new SVET-GEMS equipment was launched on board the MIR SS and a successful six-month experiments for growing up of two crops of wheat were conducted in 1996 - 97 as part of MIR-NASA-3 program. The first of these \"Greenhouse\" experiments (123 days) with the goal to grow wheat through a complete life cycle is described. Nearly 300 heads developed but no seeds were produced. A second crop of wheat was planted and after 42 days the plants were frozen for biochemical investigations. The main environmental parameters during the six-month experiments in SVET (substrate moisture and lighting period) are given. The results and the contribution to BLSS are discussed. 相似文献
992.
Presently, the french governmental bodies and space industry are joining their efforts and investments in a large technological programme named STENTOR; this programme is aiming to improve competitiveness of french space telecom industry by lowering costs and getting quickly vital technologies for the future.
First of all, this paper outlines main components of this programme and its major stages since 1994 up to 2009. Most innovating technologies of STENTOR satellite are described in terms of technical performances, development status and very promising impacts on cost and overall performances of future commercial telecom satellites; here is a preliminary list: plasma propulsion, thermal control using fluid loops and a deployable radiator, Li-Ion batteries, orbit determination with GPS receiver. Ku band regenerative payload with active antennas, etc.
Finally, some examples of service demonstrations foreseen for the in-orbit operating phase are given as illustrations. 相似文献
993.
The results of modeling the thermal deformations of a space radio telescope’s reflecting surface are presented in the paper. Calculations were performed for the versions of the most unfavorable telescope illumination by the Sun. 相似文献
994.
V.B. Betelin N.N. Smirnov V.F. Nikitin V.R. Dushin A.G. Kushnirenko V.A. Nerchenko 《Acta Astronautica》2012
Computer simulation of liquid fuel jet injection into heated atmosphere of combustion chamber, mixture formation, ignition and combustion need adequate modeling of evaporation, which is extremely important for the curved surfaces in the presence of strong heat and mass diffusion fluxes. Combustion of most widely spread hydrocarbon fuels takes place in a gas-phase regime. Thus, evaporation of fuel from the surface of droplets turns to be one of the limiting factors of the process as well. The problems of fuel droplets atomization, evaporation being the key factors for heterogeneous reacting mixtures, the non-equilibrium effects in droplets atomization and phase transitions will be taken into account in describing thermal and mechanical interaction of droplets with streaming flows. In the present paper processes of non-equilibrium evaporation of small droplets will be discussed. As it was shown before, accounting for non-equilibrium effects in evaporation for many types of widely used liquids is crucial for droplet diameters less than 100 μm, while the surface tension effects essentially manifest only for droplets below 0.1 μm. Investigating the behavior of individual droplets in a heated air flow allowed to distinguish two scenarios for droplet heating and evaporation. Small droplets undergo successively heating, then cooling due to heat losses for evaporation, and then rapid heating till the end of their lifetime. Larger droplets could directly be heated up to a critical temperature and then evaporate rapidly. Droplet atomization interferes the heating, evaporation and combustion scenario. The scenario of fuel spray injection and self-ignition in a heated air inside combustion chamber has three characteristic stages. At first stage of jet injection droplets evaporate very rapidly thus cooling the gas at injection point, the liquid jet is very short and changes for a vapor jet. At second stage liquid jet is becoming longer, because evaporation rate decreases due to decrease of temperature. But combustion of fuel vapor begins which brings to increase of heat flux to droplets and accelerates evaporation. The length of the liquid jet decreases again and remains constant slightly oscillating. 相似文献
995.
R. M. Millan M. P. McCarthy J. G. Sample D. M. Smith L. D. Thompson D. G. McGaw L. A. Woodger J. G. Hewitt M. D. Comess K. B. Yando A. X. Liang B. A. Anderson N. R. Knezek W. Z. Rexroad J. M. Scheiman G. S. Bowers A. J. Halford A. B. Collier M. A. Clilverd R. P. Lin M. K. Hudson 《Space Science Reviews》2013,179(1-4):503-530
BARREL is a multiple-balloon investigation designed to study electron losses from Earth’s Radiation Belts. Selected as a NASA Living with a Star Mission of Opportunity, BARREL augments the Radiation Belt Storm Probes mission by providing measurements of relativistic electron precipitation with a pair of Antarctic balloon campaigns that will be conducted during the Austral summers (January-February) of 2013 and 2014. During each campaign, a total of 20 small (～20 kg) stratospheric balloons will be successively launched to maintain an array of ～5 payloads spread across ～6 hours of magnetic local time in the region that magnetically maps to the radiation belts. Each balloon carries an X-ray spectrometer to measure the bremsstrahlung X-rays produced by precipitating relativistic electrons as they collide with neutrals in the atmosphere, and a DC magnetometer to measure ULF-timescale variations of the magnetic field. BARREL will provide the first balloon measurements of relativistic electron precipitation while comprehensive in situ measurements of both plasma waves and energetic particles are available, and will characterize the spatial scale of precipitation at relativistic energies. All data and analysis software will be made freely available to the scientific community. 相似文献
996.
Comparison of regular (diurnal, seasonal and solar cycle) variations of high-latitude,mid-latitude and low-latitude ionospheric characteristics has been provided on basis of local empirical models of the peak electron density and the peak height. The local empirical models were derived from the hand-scaled ionogram data recorded by DPS-4 digisondes located at Norilsk (69°N, 88°E), Irkutsk (52°N, 104°E) and Hainan (19°N, 109°E) for a 6-year period from December, 2002 to December, 2008. The technique used to build the local empirical model is described. The primary focus is diurnal-seasonal behavior under low solar activity and its change with increasing solar activity. Both common and specific features of the high-latitude (Norilsk), mid-latitude (Irkutsk) and low-latitude (Hainan) regular variations were revealed using their local empirical models. 相似文献
997.
N.J. Szewczyk J. Tillman C.A. Conley L. Granger L. Segalat A. Higashitani S. Honda Y. Honda H. Kagawa R. Adachi A. Higashibata N. Fujimoto K. Kuriyama N. Ishioka K. Fukui D. Baillie A. Rose G. Gasset B. Eche D. Chaput M. Viso 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008
998.
An intercept mission with nuclear explosives is the most effective of the practical mitigation options against the impact threat of near-Earth objects (NEOs) with a short warning time (e.g., much less than 10 years). The existing penetrated subsurface nuclear explosion technology limits the intercept velocity to less than approximately 300 m/s. Consequently, an innovative concept of blending a hypervelocity kinetic impactor with a subsurface nuclear explosion has been developed for optimal penetration, fragmentation, and dispersion of the target NEO. A proposed hypervelocity asteroid intercept vehicle (HAIV) consists of a kinetic-impact leader spacecraft and a follower spacecraft carrying nuclear explosives. This paper describes the conceptual development and design of a baseline HAIV system and its flight validation mission architecture for three mission cost classifications (e.g., $500 M, $1 B, and $1.5 B). 相似文献
999.
F B Salisbury B Bugbee D Bubenheim 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1987,7(4):123-132
Our goal is to optimize conditions for maximum yield and quality of wheat to be used in a controlled-environment, life-support system (CELSS) in a Lunar or Martian base or perhaps in a space craft. With yields of 23 to 57 g m-2 d-1 of edible biomass, a minimum size for a CELSS would be between 12 and 30 m2 per person, utilizing about 600 W m-2 of electrical energy for artificial light. Temperature, irradiance, photoperiod, carbon-dioxide levels, humidity, and wind velocity are controlled in state-of-the-art growth chambers. Nutrient solutions (adjusted for wheat) are supplied to the roots via a recirculating system that controls pH by adding HNO3 and controlling the NO3/NH4 ratio in solution. A rock-wool plant support allows direct seeding and densities up to 10,000 plants per meter2. Densities up to 2000 plants m-2 appear to increase seed yield. Biomass production increases almost linearly with increasing irradiance from 400 to 1700 micromoles m-2 s-1 of photosynthetic photon flux (PPF), but the efficiency of light utilization decreases over this range. Photoperiod and temperature both have a profound influence on floral initiation, spikelet formation, stem elongation, and fertilization. High temperatures (25 to 27 degrees C) and long days shorten the life cycle and promote rapid growth, but cooler temperatures (20 degrees C) and shorter days greatly increase seed number per head and thus yield (g m-2). The life cycle is lengthened in these conditions but yield per day (g m-2 d-1) is still increased. We have evaluated about 600 cultivars from around the world and have developed several breeding lines for our controlled conditions. Some of our ultra-dwarf lines (30 to 50 cm tall) look especially promising with high yields and high harvest indices (percent edible biomass). 相似文献
1000.
V.V. Bel&#x;giy V.V. Bugrovskiy Yu.V. Kovachich B.N. Petrov A.A. Shevyakov 《Acta Astronautica》1981,8(1):67-78
Diagnosis of a space thermoemission power unit incorporating a Topaz type reactor converter is hindered by the low potential of the measurement system. The lack of information is restored by computing from the measurement date. Examples of dynamic mode diagnosis with restoration of information on the field temperature is given. The power unit diagnosis algorithms are implemented in the onboard computer whose power is about 200,000 operations per second. Memory and computing requirements are determined from algorithms of different diagnosis degrees. Results in study of the necessary computer component redundancy are given for different models of system degradation. The redundancy level should insure that the nucleus of the computer system with a minimally necessary 4K-words memory remains in operation after three years into the mission. 相似文献