共查询到20条相似文献，搜索用时 31 毫秒
1.
Problems on designing the air-breathing ramjet electric propulsion thruster for controlling loworbit spacecraft motion are examined in the paper. Information for choosing orbits’ altitudes for reasonable application of an air-breathing ramjet electric propulsion thruster and propellant exhaust velocity is presented. Estimates of the probable increase of gas concentration in the area of air-breathing ramjet ionization are presented. The test results of the thruster are also given. 相似文献
2.
G. D. Racca A. Marini L. Stagnaro J. van Dooren L. di Napoli B. H. Foing R. Lumb J. Volp J. Brinkmann R. Grünagel D. Estublier E. Tremolizzo M. McKay O. Camino J. Schoemaekers M. Hechler M. Khan P. Rathsman G. Andersson K. Anflo S. Berge P. Bodin A. Edfors A. Hussain J. Kugelberg N. Larsson B. Ljung L. Meijer A. Mrtsell T. Nordebck S. Persson F. Sjberg 《Planetary and Space Science》2002,50(14-15)
SMART-1 is the first of the Small Missions for Advanced Research in Technology of the ESA Horizons 2000 scientific programme. The SMART-1 mission is dedicated to testing of new technologies for future cornerstone missions, using Solar-Electric Primary Propulsion (SEPP) in Deep Space. The chosen mission planetary target is the Moon. The target orbit will be polar with the pericentre close to the South-Pole. The pericentre altitude lies between 300 and 2000 km, while the apocentre will extend to about 10,000 km. During the cruise phase, before reaching the Moon, the spacecraft thrusting profile allows extended periods for cruise science. The SMART-1 spacecraft will be launched in the spring of 2003 as an auxiliary passenger on an Ariane 5 and placed into a Geostationary Transfer Orbit (GTO). The expected launch mass is about 370 kg, including 19 kg of payload. The selected type of SEPP is a Hall-effect thruster called PPS-1350. The thruster is used to spiral out of the GTO and for all orbit maneuvers including lunar capture and descent. The trajectory has been optimised by inserting coast arcs and the presence of the Moon's gravitational field is exploited in multiple weak gravity assists.The Development Phase started in October 1999 and is expected to be concluded by a Flight Acceptance Review in January 2003. The short development time for this high technology spacecraft requires a concerted effort by industry, science institutes and ESA centres. This paper describes the mission and the project development status both from a technical and programmatic standpoint. 相似文献
3.
The paper analyzes the possibility for countering ballistic perturbations of the interplanetary transfer trajectory of the spacecraft with electric propulsion (EP) associated with the temporary impossibility of the normal use of the EP in phases of the heliocentric transfer. The main result of the present study is the method for the determination of a new nominal trajectory, at any point of which the allowed duration of the emergency shutdown of electric propulsion is large enough. The numerical analysis is given for one of the possible scenarios of spacecraft injection into the operational heliocentric orbit for solar research. 相似文献
4.
New Challenges to Trajectory Design by the Use of Electric Propulsion and Other New Means of Wandering in the Solar System 总被引：1，自引：0，他引：1
Giuseppe D. Racca 《Celestial Mechanics and Dynamical Astronomy》2003,85(1):1-24
The design of spacecraft trajectories is a crucial part of a space mission design. Often the mission goal is tightly related to the spacecraft trajectory. A geostationary orbit is indeed mandatory for a stationary equatorial position. Visiting a solar system planet implies that a proper trajectory is used to bring the spacecraft from Earth to the vicinity of the planet. The first planetary missions were based on conventional trajectories obtained with chemical engine rockets. The manoeuvres could be considered 'impulsive' and clear limitations to the possible missions were set by the energy required to reach certain orbits. The gravity-assist trajectories opened a new way of wandering through the solar system, by exploiting the gravitational field of some planets. The advent of other propulsion techniques, as electric or ion propulsion and solar sail, opened a new dimension to the planetary trajectory, while at the same time posing new challenges. These 'low thrust' propulsion techniques cannot be considered 'impulsive' anymore and require for their study mathematical techniques which are substantially different from before. The optimisation of such trajectories is also a new field of flight dynamics, which involves complex treatments especially in multi-revolution cases as in a lunar transfer trajectory. One advantage of these trajectories is that they allow to explore regions of space where different bodies gravitationally compete with each other. We can exploit therefore these gravitational perturbations to save fuel or reduce time of flight. The SMART-1 spacecraft, first European mission to the Moon, will test for the first time all these techniques. The paper is a summary report on various activities conducted by the project team in these areas. 相似文献
5.
Large disturbances in the interplanetary medium were observed by several spacecraft during a period of enhanced solar activity in early February 1986. The locations of six solar flares and the spacecraft considered here encompassed more than 100° of heliolongitude. These flares during the minimum of cycle 21 set the stage for an extensive multi-spacecraft comparison performed with a two-dimensional, magnetohydrodynamic (MHD) numerical experiment. The plasma instruments on the European Space Agency (ESA)'s GIOTTO spacecraft, on its way to encounter Comet Halley in March 1986, made measurements of the solar wind for up to 8 hours per day during February. We compare solar wind measurements from the Johnstone Plasma Analyzer (JPA) experiment on GIOTTO with the MHD simulation of the interplanetary medium throughout these events. Using plasma data obtained by the IMP-8 satellite in addition, it appears that an extended period of high solar wind speed is required as well as the simulated flares to represent the interplanetary medium in this case. We also compare the plasma and magnetometer data from VEGA-1 with the MHD simulation. This comparison tends to support an interpretation that the major solar wind changes at both GIOTTO and VEGA-1 on 8 February, 1986 were due to a shock from a W05° solar flare on 6 February, 1986 (06:25 UT). The numerical experiment is considered, qualitatively, to resemble the observations at the former spacecraft, but it has less success at the latter one. 相似文献
6.
The problem of optimizing the interplanetary trajectories of a spacecraft (SC) with a solar electric propulsion system (SEPS) is examined. The problem of investigating the permissible power minimum of the solar electric propulsion power plant required for a successful flight is studied. Permissible ranges of thrust and exhaust velocity are analyzed for the given range of flight time and final mass of the spacecraft. The optimization is performed according to Portnyagin’s maximum principle, and the continuation method is used for reducing the boundary problem of maximal principle to the Cauchy problem and to study the solution/ parameters dependence. Such a combination results in the robust algorithm that reduces the problem of trajectory optimization to the numerical integration of differential equations by the continuation method. 相似文献
7.
P. Pergola K. Geurts C. Casaregola M. Andrenucci 《Celestial Mechanics and Dynamical Astronomy》2009,105(1-3):19-32
Application of low thrust propulsion to interconnect ballistic trajectories on invariant manifolds associated with multiple circular restricted three body systems has been investigated. Sun-planet three body models have been coupled to compute the two ballistic trajectories, where electric propulsion is used to interconnect these trajectories as no direct intersection in the Poincarè sections exists. The ability of a low thrust to provide the energy change required to transit the spacecraft between two systems has been assessed for some Earth to Mars transfers. The approach followed consists in a planetary escape on the unstable manifold starting from a periodic orbit around one of the two collinear libration points near the secondary body. Following the planetary escape and the subsequent coasting phase, the electric thruster is activated and executes an ad-hoc thrusting phase. The complete transfer design, composed of the three discussed phases, and possible applications to Earth–Mars missions is developed where the results are outlined in this paper. 相似文献
8.
Doppler tracking of an interplanetary spacecraft near solar conjunction is strongly affected by the plasma in the solar corona, the main competitive contribution in measurements of the gravitational deflection of light rays. With the simultaneous availability of carriers in X band and Ka band for interplanetary communications, the plasma contribution to the corona can be accurately eliminated and measured. If, as in the Cassini mission, three different observables are available, this can be done in two ways: one deals with the total plasma content in the electric approximation, even in the ionosphere and interplanetary space; another is limited to the corona, but has access to subtler effects, like the magnetic correction to the refractive index. This technique will allow important progress in the radio investigation of the solar corona. 相似文献
9.
V. M. Kulkov Yu. G. Egorov A. M. Krainov A. E. Shakhanov R. V. Elnikov 《Solar System Research》2016,50(7):533-539
Aspects of the design of small spacecraft with electric propulsion power plants for investigating minor bodies in the Solar System are examined. The results of design and ballistic analysis of transfer into an orbit of terrestrial asteroids using electric propulsion thrusters are given. The possible concept design of the spacecraft is determined and the structure of a small spacecraft with an electric propulsion power plant is presented. Parameters of the electric propulsion power plant of a small spacecraft for a flight to the minor bodies of the Solar System are estimated. 相似文献
10.
《Planetary and Space Science》1987,35(1):61-70
A double probe instrument with a probe separation of 42 m was used aboard the geostationary spacecraft GEOS-2 to measure the ambient electric field. The probes contained built-in pre-amplifiers and were current biased in order to clamp their surface potential near to the local plasma potential while the spacecraft surfaces floated at a more positive potential. Depending on the plasma density, the potential difference ranges between 1 V (dense plasma, Ne > 10cm−3) and more than 10 V (tenuous plasma, Ne < 3 cm−3). In the case of the more tenuous plasma, photoelectrons emitted from the probes tend to be picked up by the more positive potential of the wire booms. The net current of this electron flow depends on the spin orientation of the wire booms with respect to the Sun. It occurrs in the data as a spurious signal and was already earlier found to be a function of the spacecraft potential. With data from quiet magnetospheric conditions (Kp ⩽ 2) the long-term variation of the spurious signal was investigated. It turned out to be constant during the initial 3 y of the mission. Afterwards, as from 1981, it became smaller and did so for the following 2 y. In 1983, the end of the 5-y period of available data, it had vanished. The cause of the drop is suggested to be a consequence of the partial removal of the conductive surface layer of the wire booms by sputter effects. Expressions were derived that yield more accurate correction of the data. A valuable by-product of this work is the statistical relation of spacecraft potential and total electron flux. 相似文献
11.
The power-limited solar electric propulsion system is considered more practical in mission design. An accurate mathematical model of the propulsion system, based on experimental data of the power generation system, is used in this paper. An indirect method is used to deal with the time-optimal and fuel-optimal control problems, in which the solar electric propulsion system is described using a finite number of operation points, which are characterized by different pairs of thruster input power. In order to guarantee the integral accuracy for the discrete power-limited problem, a power operation detection technique is embedded in the fourth-order Runge-Kutta algorithm with fixed step. Moreover, the logarithmic homotopy method and normalization technique are employed to overcome the difficulties caused by using indirect methods. Three numerical simulations with actual propulsion systems are given to substantiate the feasibility and efficiency of the proposed method. 相似文献
12.
We studied the causes of recurrent geomagnetic activity by analyzing interplanetary magnetic field and plasma data from Earth-orbiting spacecraft in the interval from November 1973 to February 1974. This interval includes the start of two long sequences of geomagnetic activity and two corresponding corotating interplanetary streams. In general, the geomagnetic activity was related to an electric field which was primarily due to two factors: (1) the ordered, mesoscale pattern of the stream itself and (2) random, smaller-scale fluctuations in the southward component of the interplanetary magnetic field Bz. The geomagnetic activity in each recurrent sequence consisted of two successive stages. The first stage was usually the most intense and it occurred during the passage of the interaction region at the front of a stream. It was related to a V × B electric field which was large primarily because the amplitude of the fluctuations in Bz was large in the interaction region. It is suggested that these large amplitudes of Bz were primarily produced in the interplanetary medium by compression of ambient fluctuations as the stream steepened in transit to 1 A.U. The second stage of geomagnetic activity immediately following the first was associated with the highest speeds in the stream. It was, among other things, related to a V × B electric field which was large mainly because of the high speeds. 相似文献
13.
G. Le Chat A. Zaslavsky N. Meyer-Vernet K. Issautier S. Belheouane F. Pantellini M. Maksimovic I. Zouganelis S. D. Bale J. C. Kasper 《Solar physics》2013,286(2):549-559
New measurements using radio and plasma-wave instruments in interplanetary space have shown that nanometer-scale dust, or nanodust, is a significant contributor to the total mass in interplanetary space. Better measurements of nanodust will allow us to determine where it comes from and the extent to which it interacts with the solar wind. When one of these nanodust grains impacts a spacecraft, it creates an expanding plasma cloud, which perturbs the photoelectron currents. This leads to a voltage pulse between the spacecraft body and the antenna. Nanodust has a high charge/mass ratio, and therefore can be accelerated by the interplanetary magnetic field to the speed of the solar wind: significantly faster than the Keplerian orbital speeds of heavier dust. The amplitude of the signal induced by a dust grain grows much more strongly with speed than with mass of the dust particle. As a result, nanodust can produce a strong signal despite its low mass. The WAVES instruments on the twin Solar TErrestrial RElations Observatory spacecraft have observed interplanetary nanodust particles since shortly after their launch in 2006. After describing a new and improved analysis of the last five years of STEREO/WAVES Low Frequency Receiver data, we present a statistical survey of the nanodust characteristics, namely the rise time of the pulse voltage and the flux of nanodust. We show that previous measurements and interplanetary dust models agree with this survey. The temporal variations of the nanodust flux are also discussed. 相似文献
14.
《Planetary and Space Science》1999,47(8-9):1029-1050
We predict the amount of cometary, interplanetary, and interstellar cosmic dust that is to be measured by the Cometary and Interstellar Dust Analyzer (CIDA) and the aerogel collector on board the Stardust spacecraft during its fly-by of comet P⧸Wild 2 and during the interplanetary cruise phase. We give the dust flux on the spacecraft during the encounter with the comet using both, a radially symmetric and an axially symmetric coma model. At closest approach, we predict a total dust flux of 1060 m−2 s−1 for the radially symmetric case and 1065 m−2 s−1 for the axially symmetric case. This prediction is based on an observation of the comet at a heliocentric distance of 1.7 AU. We reproduce the measurements of the Giotto and VEGA missions to comet P⧸Halley using the same model as for the Stardust predictions. The planned measurements of interstellar dust by Stardust have been triggered by the discovery of interstellar dust impacts in the data collected by the Ulysses and Galileo dust detector. Using the Ulysses and Galileo measurements we predict that 25 interstellar particles, mainly with masses of about 10−12 g, will hit the target of the CIDA experiment. The interstellar side of the aerogel collector will contain 120 interstellar particles, 40 of which with sizes greater than 1 μm. Furthermore, we investigate the contamination of the CIDA and collector measurements by interplanetary particles during the cruise phase. 相似文献
15.
The European SMART-1 mission to the Moon, primarily a testbed for innovative technologies, was launched in September 2003 and will reach the Moon in 2005. On board are several scientific instruments, including the point-spectrometer SMART-1 Infrared Spectrometer (SIR). Taking into account the capabilities of the SMART-1 mission and the SIR instrument in particular, as well as the open questions in lunar science, a selection of targets for SIR observations has been compiled. SIR can address at least five topics: (1) Surface/regolith processes; (2) Lunar volcanism; (3) Lunar crust structure; (4) Search for spectral signatures of ices at the lunar poles; and (5) Ground truth and study of geometric effects on the spectral shape. For each topic we will discuss specific observation modes, necessary to achieve our scientific goals. The majority of SIR targets will be observed in the nadir-tracking mode. More than 100 targets, which require off-nadir pointing and off-nadir tracking, are planned. It is expected that results of SIR observations will significantly increase our understanding of the Moon. Since the exact arrival date and the orbital parameters of the SMART-1 spacecraft are not known yet, a more detailed planning of the scientific observations will follow in the near future. 相似文献
16.
17.
S.K Dunkin M GrandeI Casanova V FernandesD.J Heather B KellettK Muinonen S.S RussellR Browning N WalthamD Parker B KentC.H Perry B SwinyardA Perry J FeradayC Howe K PhillipsG McBride J HuovelinP Muhli P.J HakalaO Vilhu N ThomasD Hughes H AlleyneM Grady R LundinS Barabash D BakerP.E Clark C.D MurrayJ Guest L.C d'UstonS Maurice B FoingA Christou C OwenP Charles J LaukkanenH Koskinen M KatoK Sipila S NenonenM Holmstrom N BhandariR Elphic D Lawrence 《Planetary and Space Science》2003,51(6):435-442
The D-CIXS X-ray spectrometer on ESA's SMART-1 mission will provide the first global coverage of the lunar surface in X-rays, providing absolute measurements of elemental abundances. The instrument will be able to detect elemental Fe, Mg, Al and Si under normal solar conditions and several other elements during solar flare events. These data will allow for advances in several areas of lunar science, including an improved estimate of the bulk composition of the Moon, detailed observations of the lateral and vertical nature of the crust, chemical observations of the maria, investigations into the lunar regolith, and mapping of potential lunar resources. In combination with information to be obtained by the other instruments on SMART-1 and the data already provided by the Clementine and Lunar Prospector missions, this information will allow for a more detailed look at some of the fundamental questions that remain regarding the origin and evolution of the Moon. 相似文献
18.
K. Muinonen Yu. Shkuratov A. Ovcharenko J. Piironen D. Stankevich O. Miloslavskaya S. Kaasalainen J. -L. Josset 《Planetary and Space Science》2002,50(14-15)
The lunar surface reveals a sharp opposition effect, which is to be explained by the shadowing and coherent backscattering mechanisms. Generalizing the radiative transfer theory via Monte Carlo methods, we are carrying out studies of backscattering in regolith-like scattering media. We have also started systematic laboratory measurements of structural simulators of lunar regolith. The SMART-1 AMIE and D-CIXS/XSM experiments provide us a unique opportunity for a simultaneous multiwavelength study of the lunar regolith close to opposition, since the SMART-1 spacecraft will pass over several different types of lunar surface at zero phase angles. Results of our theoretical and laboratory investigations can be used as a basis to interpret the SMART-1 AMIE and D-CIXS/XSM experiments. In particular, it seems to be possible to estimate regional variations of regolith particle volume fraction and their size. A short review of observational, experimental and theoretical works is also presented here. 相似文献
19.
The employment of a large area Phase Fresnel Lens (PFL) in a gamma-ray telescope offers the potential to image astrophysical phenomena with micro-arcsecond (μ′′) angular resolution [1]. In order to assess the feasibility of this concept, two detailed studies have been conducted of formation flying missions in which a Fresnel lens capable of focussing gamma-rays and the associated detector are carried on two spacecraft separated by up to 106 km. These studies were performed at the NASA Goddard Space Flight Center Integrated Mission Design Center (IMDC) which developed spacecraft, orbital dynamics, and mission profiles. The results of the studies indicated that the missions are challenging but could be accomplished with technologies available currently or in the near term. The findings of the original studies have been updated taking account of recent advances in ion thruster propulsion technology. 相似文献