共查询到20条相似文献，搜索用时 15 毫秒
1.
《New Astronomy》2003,8(5):371-390
We have proposed to test the equivalence principle (EP) in low Earth orbit with a rapidly rotating differential accelerometer (made of weakly coupled concentric test cylinders) whose rotation provides high frequency signal modulation and avoids severe limitations otherwise due to operation at room temperature [PhRvD 63 (2001) 101101]. Although the accelerometer has been conceived for best performance in absence of weight, we have designed, built and tested a variant of it at 1-g. Here we report the results of measurements performed so far. Losses measured with the full system in operation yield a quality factor only four times smaller than the value required for the proposed high accuracy EP test in space. Unstable whirl motions, which are known to arise in the system and might be a matter of concern, are found to grow as slowly as predicted and can be stabilized. The capacitance differential read-out (the mechanical parts, electronics and software for data analysis) is in all similar to what is needed in the space experiment. In the instrument described here the coupling of the test masses is 24 000 times stiffer than in the one proposed for flight, which makes it 24 000 times less sensitive to differential displacements. With this stiffness it should detect test masses separations of 1.5·10−2 μm, while so far we have achieved only 1.5 μm, because of large perturbations—due to the motor, the ball bearings, the non-perfect verticality of the system—all of which, however, are absent in space. The effects of these perturbations should be reduced by 100 times in order to perform a better demonstration. Further instrument improvements are underway to fill this gap and also to reduce its stiffness, thus increasing its significance as a prototype of the space experiment. 相似文献
2.
Human space flight represents a heady mix of bravery and drama which can be inspirational to nations and to humankind but
at huge economic cost. Due to the current high launch costs only a handful of people have ventured beyond low Earth orbit
and walked on the Moon, propelled by aspirations related more to the Cold War than to science. Problems with reusable launch
vehicle development mean that severe launch cost limitations will exist for some time. Meanwhile, cheaper robotic probes have
visited all the planets except Pluto, flown by comets, landed on Mars, Venus and an asteroid, have probed Jupiter's atmosphere
and studied the Universe beyond our own solar system with telescopes. Using these data we are determining mankind's place
in the Universe. Public interest in the historic Eros landing eclipsed a simultaneous space walk at the fledgling International
Space Station and the Mars Pathfinder landing generated hundreds of millions of website hits in a few days. Given the fact
that hundreds of Mars missions could be flown for the still-escalating cost of the International Space Station, the unsuitability
of human bodies for deep space exploration, and the advances in 3-d and virtual reality techniques, we discuss whether human
exploration needs a place in a realistic, useful and inspirational space programme.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
3.
Life In Space: An Introduction To Space Life Sciences And The International Space Station 总被引：1，自引：0，他引：1
The impact of the space environment upon living organisms is profound. Its effects range from alterations in sub-cellular
processes to changes in the structure and function of whole organ systems. As the number of astronaut and cosmonaut crews
flown in space has grown, so to has our understanding of the effects of the space environment upon biological systems. There
are many parallels between the physiology of space flight and terrestrial disease processes, and the response of astronaut
crews themselves to long-duration space deployment is therefore of central interest.
In the next 15 years the International Space Station (ISS) will serve as a permanently manned dedicated life and physical
sciences platform for the further investigation of these phenomena. The European Space Agency's Columbus module will hold
the bulk of the ISS life science capability and, in combination with NASA's Human Research Facility (HRF) will accommodate
the rack mounted experimental apparatus. The programme of experimentation will include efforts in fundamental biology, human
physiology, behavioural science and space biomedical research.
In the four decades since Yuri Gagarin first orbited the Earth, space life science has emerged as a field of study in its
own right. The ISS takes us into the next era of human space exploration, and it is hoped that its programme of research will
yield new insights, novel therapeutic interventions, and improved biotechnology for terrestrial application.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
4.
Michael Dellnitz Oliver Junge Marcus Post Bianca Thiere 《Celestial Mechanics and Dynamical Astronomy》2006,95(1-4):357-370
Recently new techniques for the design of energy efficient trajectories for space missions have been proposed that are based on the circular restricted three body problem as the underlying mathematical model. These techniques exploit the structure and geometry of certain invariant sets and associated invariant manifolds in phase space to systematically construct energy efficient flight paths. In this paper, we extend this model in order to account for a continuously applied control force on the spacecraft as realized by certain low thrust propulsion systems. We show how the techniques for the trajectory design can be suitably augmented and compute approximations to trajectories for a mission to Venus. 相似文献
5.
The mission designed to explore asteroids has nowadays become a hot spot of deep space exploration, and the accessibility of the explored objects is the most important problem to make clear. The number of asteroids is large, and it needs an enormous quantity of calculations to evaluate the accessibility for all asteroids. In this paper, based on the direct transfer strategy, we have calculated the accessibility for the different regions of the solar system and compared it with the distribution of asteroids. It is found that most main-belt asteroids are accessible by the direct transfer orbit with the launch energy of C3 = 50 km2/s2, and that with an additional small velocity correction, the designed trajectory is able to realize the multi-target flyby mission. Such a kind of multi-target flyby can reach the same effect of the orbit manoeuvre in the ΔV-EGA trajectory scheme[1,2]. Being assisted by the earth's gravity, the accompanying flight with asteroids or the exploration of more distant asteroids can be realized with a lower energy. In the end, as an example, a trajectory scheme is given, in which the probe flies by multiple main-belt asteroids at first, then with the assistance of the earth's gravity, it makes the accompanying flight to a more distant asteroid. 相似文献
6.
The design of detector systems for flight applications requires the consideration of a number of issues unique to space instrumentation. Flight detectors must endure hostile radiation environments and thermal extremes. Paramount importance is given to reliability since inflight replacement is at best difficult and usually impossible. Flight detectors are also significant cost and design drivers since they often determine key requirements for flight instruments such as volume, mass, power consumption, heat dissipation and communications budgets. In this paper we describe the primary concerns in developing flight detector systems, and review the challenges posed by future NASA and ESA space science missions for detector development. 相似文献
7.
John-David F. Bartoe 《Astrophysics and Space Science》1982,84(1):115-132
An Image Drift Compensation System has been designed for a solar pointed space borne telescope and has performed successfully on two sounding rocket flights, yielding new scientific results. The system employs limb-sensing photodiodes at the telescope focal plane and provides drift compensation to better than 0.1 arc sec. A variation of the system will be used on the Shuttle/Spacelab 2 flight of the High Resolution Telescope and Spectrograph (HRTS) Instrument.Originally submitted to the journalSpace Science Instrumentation. 相似文献
8.
Michael Dellnitz Sina Ober-Blöbaum Marcus Post Oliver Schütze Bianca Thiere 《Celestial Mechanics and Dynamical Astronomy》2009,105(1-3):33-59
In this article, we introduce a novel three-step approach for solving optimal control problems in space mission design. We demonstrate its potential by the example task of sending a group of spacecraft to a specific Earth L 2 halo orbit. In each of the three steps we make use of recently developed optimization methods and the result of one step serves as input data for the subsequent one. Firstly, we perform a global and multi-objective optimization on a restricted class of control functions. The solutions of this problem are (Pareto-)optimal with respect to ΔV and flight time. Based on the solution set, a compromise trajectory can be chosen suited to the mission goals. In the second step, this selected trajectory serves as initial guess for a direct local optimization. We construct a trajectory using a more flexible control law and, hence, the obtained solutions are improved with respect to control effort. Finally, we consider the improved result as a reference trajectory for a formation flight task and compute trajectories for several spacecraft such that these arrive at the halo orbit in a prescribed relative configuration. The strong points of our three-step approach are that the challenging design of good initial guesses is handled numerically by the global optimization tool and afterwards, the last two steps only have to be performed for one reference trajectory. 相似文献
9.
In flight energy calibration and gain corrections for the hard X- and soft gamma-ray telescope Sigma
F. Lei J. P. Leray P. Mandrou J. Paul J. P. Roques F. Lebrun 《Experimental Astronomy》1992,2(6):399-408
The French soft -ray coded mask imaging telescope on board Soviet spacecraft GRANAT has experienced some unexpected gain drifts during its operation in the space. This gain instability seriously affected its data analysis and scientific interpretation of the results. After a detailed study of its background spectra and the long term performance of the detector, we have identified several background features which enable us to perform the in flight energy calibrations and gain corrections for the observations. The precision of such an energy calibration is estimated to be in the order of 0.5%, which is accurate enough for all types of data analysis such as spectrum de-convolution, and summation of observation spectra. More importantly it makes the search of astrophysical line features in the spectrum possible.On leave fromUniversity of Southampton, U.K. 相似文献
10.
A.W. Kirkpatrick M.A. Keaney K. Bentz M. Tyssen C.G. Ball S.M. Grenon T.J. Broderick 《Planetary and Space Science》2010,58(4):717-723
Emergency surgery will be needed to prevent death if humans are used to explore beyond low earth's orbit. Laparoscopic surgery (LS) is envisioned as a less invasive option for space, but will induce further stresses and complicate logistical requirements. Thus, further study into the technology and physiology of LS in weightlessness is required. We recently utilized the National Research Council of Canada's Flight Research Laboratory's Falcon 20 aircraft as a terrestrial analogue space environment (TASE) for space surgery research. The Falcon 20 had never been used for this purpose nor had the involved teams collaborated previously. There were many process challenges including the lack of antecedent surgical studies on this aircraft, a requirement for multiple disciplines who were unfamiliar and geographically distant from each other, flight performance limitations with the Falcon 20, complex animal care requirements, requirements for prototypical in-flight life-support surgical suites, financial limitations, and a need to use non-flight hardened technologies. Stepwise suggested solutions to these challenges are outlined as guidelines for future investigators intending similar research. Overall, the Falcon 20 TASE, backed by the flight resources, especially the design and fabrication capabilities of the NRC-FRL, provide investigators with a versatile and responsive opportunity to pursue research into advanced medical techniques that will be needed to save lives during space exploration. 相似文献
11.
Ultra-violet image sensors and UV optics have been developed for a variety of space borne UV astronomy missions. Technology progress has to be made to improve the performance of future UV space missions. Throughput is the most important technology driver for the future. Required developments for different UV detector types – detectors are one of the most problematic and critical parts of a space born mission – and for optical components of the instruments are given in these guidelines. For near future missions we need high throughput optics with UV sensors of large formats, which show simultaneously high quantum efficiency and low noise performance. 相似文献
12.
Chad G. Ball Marilyn A. Keaney Rosaleen Chun Michelle Tyssen Timothy J. Broderick 《Planetary and Space Science》2010,58(4):732-740
Background
Multiple nations are actively pursuing manned exploration of space beyond low-earth orbit. The responsibility to improve surgical care for spaceflight is substantial. Although the use of parabolic flight as a terrestrial analogue to study surgery in weightlessness (0 g) is well described, minimal data is available to guide the appropriate delivery of anesthesia. After studying anesthetized pigs in a 0 g parabolic flight environment, our group developed a comprehensive protocol describing prolonged anesthesia in a parabolic flight analogue space surgery study (PFASSS). Novel challenges included a physically remote vivarium, prolonged (>10 h) anesthetic requirements, and the provision of veterinary operating room/intensive care unit (ICU) equivalency on-board an aircraft with physical dimensions of <1.5 m2 (Falcon 20). Identification of an effective anesthetic regime is particularly important because inhalant anesthesia cannot be used in-flight.Methods
After ethical approval, multiple ground laboratory sessions were conducted with combinations of anesthetic, pre-medication, and induction protocols on Yorkshire-cross specific pathogen-free (SPF) pigs. Several constant rate infusion (CRI) intravenous anesthetic combinations were tested. In each regimen, opioids were administered to ensure analgesia. Ventilation was supported mechanically with blended gradients of oxygen. The best performing terrestrial 1 g regime was flight tested in parabolic flight for its effectiveness in sustaining optimal and prolonged anesthesia, analgesia, and maintaining hemodynamic stability. Each flight day, a fully anesthetized, ventilated, and surgically instrumented pig was transported to the Flight Research Laboratory (FRL) in a temperature-controlled animal ambulance. A modular on-board surgical/ICU suite with appropriate anesthesia/ICU and surgical support capabilities was employed.Results
The mean duration of anesthesia (per flight day) was 10.28 h over four consecutive days. A barbiturate and ketamine-based CRI anesthetic regimen supplemented with narcotic analgesia by bolus administration offered the greatest prolonged hemodynamic stability through an IV route (within multiple transport vehicles and differing gravitational environments). Standardization and pre-packaging of anesthesia, emergency pharmaceuticals, and consumables were found to facilitate the interchange of the veterinary anesthesia team members between flights. This operational process was extremely challenging.Conclusions
With careful organization of caregivers, equipment and protocols, providing anesthesia and life support in weightlessness is theoretically possible. Unfortunately, human resource costs are extensive and likely overwhelming. Comprehensive algorithms for extended spaceflight must recognize these costs prior to making assumptions or attempting to provide critical care in space. 相似文献13.
14.
Elhanan Almoznino Noah Brosch Ido Finkelman Hagai Netzer Erez R. Yacoby Jeremy Topaz Nachman Saar 《Astrophysics and Space Science》2009,320(4):321-341
We describe in detail the procedures used for the ground testing and calibration of the flight model of the TAUVEX space telescope.
We present the measurements done for this purpose, the various assumptions adopted during the ground calibration process,
the results obtained, and provide a first approximation to the real performance of the experiment.
The results of the ground-based calibration are that the system complies with the predicted performance in all aspects except
for the total throughput, which is a factor of ∼5 smaller than expected. However, the instrument sensitivity measurement is
highly uncertain due to known limitations of the available equipment and a more accurate calibration will be performed in
orbit. 相似文献
15.
The heliosphere represents a uniquely accessible domain of space, where fundamental physical processes common to solar, astrophysical and laboratory plasmas can be studied under conditions impossible to reproduce on Earth and unfeasible to observe from astronomical distances. Solar Orbiter, the first mission of ESA’s Cosmic Vision 2015?–?2025 programme, will address the central question of heliophysics: How does the Sun create and control the heliosphere? In this paper, we present the scientific goals of the mission and provide an overview of the mission implementation. 相似文献
16.
Levasseur-Regourd A.C. Cabane M. Haudebourg V. Worms J.C. 《Earth, Moon, and Planets》1998,80(1-3):343-368
Most of our knowledge on heterogeneous media in the Universe comes from the light they scatter. This light is mainly linearly
polarized, and the polarization phase curves contain information about the properties of the scattering dust. In the solar
system, the dust seems to be made of irregular aggregates with a size greater than a few microns and a fractal structure.
Many constraints appear in the scattering computations, due to the trickiness of the mathematical calculations, and to our
ignorance of the precise structure of the dust. This leads to the necessity to perform light scattering measurements on characteristic
aggregates, built under low velocity ballistic collisions. Microgravity is a sensible way to achieve such measurements on
a cloud of levitating and aggregating dust particles. A first step has been the PROGRA2 experiment, which operates during parabolic flights on an aircraft. The instrument is a polar nephelometer measuring successively
the light scattered by a dust sample at various angles; it is fully operational, and will provide a data base of polarization
phase curves. A second step is the CODAG-SR experiment, which uses the duration of a rocket flight to build up dust aggregates.
The instrument measures simultaneously the light scattered at numerous phase angles; it is now space qualified, and should
provide in a near future a monitoring of the intensity and polarization phase curves while the aggregation processes are taking
place.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
17.
Gabriel Mititelu 《Celestial Mechanics and Dynamical Astronomy》2009,103(4):327-342
A practical and important problem encountered during the atmospheric re-entry phase is to determine analytical solutions for
the space vehicle dynamical equations of motion. The author proposes new solutions for the equations of trajectory and flight-path
angle of the space vehicle during the re-entry phase in Earth’s atmosphere. Explicit analytical solutions for the aerodynamic
equations of motion can be effectively applied to investigate and control the rocket flight characteristics. Setting the initial
conditions for the speed, re-entering flight-path angle, altitude, atmosphere density, lift and drag coefficients, the nonlinear
differential equations of motion are linearized by a proper choice of the re-entry range angles. After integration, the solutions
are expressed with the Exponential Integral, and Generalized Exponential Integral functions. Theoretical frameworks for proposed
solutions as well as, several numerical examples, are presented. 相似文献
18.
《Planetary and Space Science》2007,55(4):383-400
We studied the stability of aromatic compounds in low Earth orbit environment and describe the scientific results and successful flight of the ORGANICS experiment on-board the BIOPAN V space exposure facility. This experiment investigated the photo stability of large organic molecules in low Earth orbit. Thin films of selected organic molecules, such as polycyclic aromatic hydrocarbons (PAHs) and the fullerene C60 were subjected to the low Earth orbit environment and the samples were monitored before and after flight. PAHs and fullerenes have been proposed as carriers for a number of astronomical absorption and emission features and are also identified in meteorites. Our experiment on BIOPAN V was exposed to a total fluence of 602.45 kJ m−2 for photons in the range 170–280 nm. The experiment was also intended as a hardware test-flight for a long-term exposure experiment (Survival of organics in space) on the EXPOSE facility on the International Space Station (ISS). For the small fluence that was collected during the BIOPAN V experiment we found little evidence of photo-destruction. The results confirm that PAH molecules are very stable compounds in space. The small differences in destruction rates that are expected to arise among the PAH samples as a function of molecular size and structure will only show after the longer irradiation fluences that are expected in the exposure experiment on the ISS. 相似文献
19.
We describe concepts for small space telescopes that are able to provide significant UV science and can be realized with small (but realistic) budgets. The concepts are based on nano-satellites carrying small optics, with no redundancy, without producing intermediate models prior to flight model, and using COTS (custom off-the-shelf) components. We describe a few concepts of deployable optics that could provide large collecting areas and high angular resolution while packaged in the small volume of a nano-satellite. We point out areas where technological development is still required. 相似文献
20.
This paper presents an analysis of interactions between the space shuttle Orbiter and the ionosphere based on thermal plasma data obtained from a Spherical Retarding Potential Analyzer (SRPA) and a Langmuir Probe (LP) flown on the third Space Shuttle flight (STS-3) in March 1982. While previous work on spacecraft-plasma interactions has dealt with wake effects, the present work deals with effects that are seen in ram conditions that have not been previously discussed. One observation is a higher degree of plasma turbulence than has been reported from unmanned spacecraft measurements that manifests itself as a frequency component at 2.2 kHz in the SRPA signal. We also see unusually high number densities of what appear to be ions with a mass of at least 30 or 32 amu and a temperature in the range 2000–3000 K. Coincident with the enhanced molecular ion species we see the temperature of the thermal electrons elevated to above 5000 K. It is hypothesized that these measurements are evidence for a plasma instability resulting from the motion of the outgassing Orbiter through the ionosphere. 相似文献