共查询到20条相似文献，搜索用时 31 毫秒
1.
Yu. D. Kotov V. N. Yurov E. E. Lupar K. F. Vlasik A. I. Arkhangelsky A. S. Glyanenko I. V. Rubtsov V. V. Kadilin V. G. Tyshkevich 《Solar System Research》2011,45(2):97-122
The NATALYA-2M high-energy radiation spectrometer is an element of the complex of scientific equipment of the CORONAS-PHOTON
satellite. The instrument intended for registering gamma radiation of solar flares in the broad energy range of 0.2–1600 MeV
as well as neutrons of solar origin with energies of 20–300 MeV represents itself as a scintillation spectrometer based on
CsI(Tl) crystals with a total area of 32 × 38 cm2 and the thickness of 18 cm. The spectra and time profiles of the gamma quanta count rates are measured in four subranges:
R (0.2–2 MeV), L (1–18 MeV), M (7–250 MeV), and H (50–1600 MeV). Depending on the gamma radiation energy, the effective area
of the instrument varies within the range from 750 to 900 cm2, and the energy resolution at the Cs-137 line (662 keV) is 10%, it being about 30% at energies higher than 50 MeV. A system
of stabilization based on the signal from the generator of reference light pulses is used to provide stability and automated
adjustment of the parameters of spectrometric modules. The measuring channels of the instrument are calibrated during the
flight using a source of “tagged” gamma quanta on the Co-60 radioactive isotope. Polystyrene scintillation counters are used
to provide protection from the background of charged particles. The “CORONAS-PHOTON” spacecraft (SC) was launched from the
Plesetsk spaceport on January 30, 2009, to a low circular near-Earth orbit (the altitude is 550 km, the inclination is 82.5°).
On February 27, the first scientific data were obtained from the NATALYA-2M instrument. The results of the flight calibration
of the instrument detectors in different energy channels demonstrated good agreement with the ground measurements. The paper
describes the instrument and observational potentials of the NATALYA-2M spectrometer, gives the results of the adjustment
and calibration, and exemplifies the registration of gamma-ray bursts (GRBs)on the orbit. 相似文献
2.
Yuan Ren Pierpaolo Pergola Elena Fantino Bianca Thiere 《Celestial Mechanics and Dynamical Astronomy》2012,112(1):1-21
Over the past three decades, ballistic and impulsive trajectories between libration point orbits (LPOs) in the Sun–Earth–Moon
system have been investigated to a large extent. It is known that coupling invariant manifolds of LPOs of two different circular
restricted three-body problems (i.e., the Sun–Earth and the Earth–Moon systems) can lead to significant mass savings in specific
transfers, such as from a low Earth orbit to the Moon’s vicinity. Previous investigations on this issue mainly considered
the use of impulsive maneuvers along the trajectory. Here we investigate the dynamical effects of replacing impulsive ΔV’s with low-thrust trajectory arcs to connect LPOs using invariant manifold dynamics. Our investigation shows that the use
of low-thrust propulsion in a particular phase of the transfer and the adoption of a more realistic Sun–Earth–Moon four-body
model can provide better and more propellant-efficient solution. For this purpose, methods have been developed to compute
the invariant tori and their manifolds in this dynamical model. 相似文献
3.
The “Fast X-ray Monitor” (BRM) instrument operated in the complex of the scientific instruments onboard the CORONAS-PHOTON
satellite from February 19, 2009, until December 1, 2009. The instrument is intended for the registration of the hard X-ray
radiation of solar flares in the 20–600 keV energy range in six differential energy channels (20–30, 30–40, 40–50, 50–70,
70–130, and 130–600 keV) with temporal resolution to 1 ms. In the instrument, a detector based on the YAP: Ce scintillator
is used; this detector is 70 mm in diameter and 10 mm thick (the decay time is about 28 ns). For the decrease of the back-ground
charge of the detector, the collimator limiting the angle of view of the instrument of value 12° is mounted over the scintillator.
The effective area of the detector amounts to 27.7 cm2 (at the X-ray radiation energy 80 keV), and the dead time of the detector is 1 μs. Over the operation onboard the CORONAS-PHOTON
satellite, the BRM instrument has registered gamma ray burst series and, perhaps, one solar flare of the class C1.3 on October
26, 2009. 相似文献
4.
Yu. I. Denisov V. V. Kalegaev I. N. Myagkova M. I. Panasyuk 《Solar System Research》2011,45(3):206-211
This paper describes the design and principles of operation of the Electron-M-PESCA instrument, provides a specification of
the information system to store and access the measurement results registered with Electron-M-PESCA, and evaluates the prospects
of applying this system to assess the radiation conditions in the near-Earth space. It presents an analysis of the increase
in relativistic electron flows with energies of 1–4 MeV registered in Earth’s outer radiation belt in the middle of March
2009 after weak magnetic disturbances caused by the approach of a high-speed solar wind flow as an example of on-line analysis
of research information obtained with Electron-M-PESCA. 相似文献
5.
Position and velocity perturbations for the determination of geopotential from space geodetic measurements 总被引：10，自引：0，他引：10
Peiliang Xu 《Celestial Mechanics and Dynamical Astronomy》2008,100(3):231-249
Although space geodetic observing systems have been advanced recently to such a revolutionary level that low Earth Orbiting
(LEO) satellites can now be tracked almost continuously and at the unprecedented high accuracy, none of the three basic methods
for mapping the Earth’s gravity field, namely, Kaula linear perturbation, the numerical integration method and the orbit energy-based
method, could meet the demand of these challenging data. Some theoretical effort has been made in order to establish comparable
mathematical modellings for these measurements, notably by Mayer-Gürr et al. (J Geod 78:462–480, 2005). Although the numerical
integration method has been routinely used to produce models of the Earth’s gravity field, for example, from recent satellite
gravity missions CHAMP and GRACE, the modelling error of the method increases with the increase of the length of an arc. In
order to best exploit the almost continuity and unprecedented high accuracy provided by modern space observing technology
for the determination of the Earth’s gravity field, we propose using measured orbits as approximate values and derive the
corresponding coordinate and velocity perturbations. The perturbations derived are quasi-linear, linear and of second-order
approximation. Unlike conventional perturbation techniques which are only valid in the vicinity of reference mean values,
our coordinate and velocity perturbations are mathematically valid uniformly through a whole orbital arc of any length. In
particular, the derived coordinate and velocity perturbations are free of singularity due to the critical inclination and
resonance inherent in the solution of artificial satellite motion by using various types of orbital elements. We then transform
the coordinate and velocity perturbations into those of the six Keplerian orbital elements. For completeness, we also briefly
outline how to use the derived coordinate and velocity perturbations to establish observation equations of space geodetic
measurements for the determination of geopotential. 相似文献
6.
Synoptic maps of white-light coronal brightness from SOHO/LASCO C2 and distributions of solar wind velocity obtained from
interplanetary scintillation are studied. Regions with velocity V≈300 – 450 km s−1 and increased density N>10 cm−3, typical of the “slow” solar wind originating from the belt and chains of streamers, are shown to exist at Earth’s orbit,
between the fast solar wind flows (with a maximum velocity V
max ≈450 – 800 km s−1). The belt and chains of streamers are the main sources of the “slow” solar wind. As the sources of “slow” solar wind, the
contribution from the chains of streamers may be comparable to that from the streamer belt. 相似文献
7.
In the present paper the equations of the orbital motion of the major planets and the Moon and the equations of the three–axial
rigid Earth’s rotation in Euler parameters are reduced to the secular system describing the evolution of the planetary and
lunar orbits (independent of the Earth’s rotation) and the evolution of the Earth’s rotation (depending on the planetary and
lunar evolution). Hence, the theory of the Earth’s rotation can be presented by means of the series in powers of the evolutionary
variables with quasi-periodic coefficients with respect to the planetary–lunar mean longitudes. This form of the Earth’s rotation
problem is compatible with the general planetary theory involving the separation of the short–period and long–period variables
and avoiding the appearance of the non–physical secular terms. 相似文献
8.
S. Schiller G. M. Tino P. Gill C. Salomon U. Sterr E. Peik A. Nevsky A. Görlitz D. Svehla G. Ferrari N. Poli L. Lusanna H. Klein H. Margolis P. Lemonde P. Laurent G. Santarelli A. Clairon W. Ertmer E. Rasel J. Müller L. Iorio C. Lämmerzahl H. Dittus E. Gill M. Rothacher F. Flechner U. Schreiber V. Flambaum Wei-Tou Ni Liang Liu Xuzong Chen Jingbiao Chen Kelin Gao L. Cacciapuoti R. Holzwarth M. P. Heß W. Schäfer 《Experimental Astronomy》2009,23(2):573-610
The Einstein Gravity Explorer mission (EGE) is devoted to a precise measurement of the properties of space-time using atomic
clocks. It tests one of the most fundamental predictions of Einstein’s Theory of General Relativity, the gravitational redshift,
and thereby searches for hints of quantum effects in gravity, exploring one of the most important and challenging frontiers
in fundamental physics. The primary mission goal is the measurement of the gravitational redshift with an accuracy up to a
factor 104 higher than the best current result. The mission is based on a satellite carrying cold atom-based clocks. The payload includes
a cesium microwave clock (PHARAO), an optical clock, a femtosecond frequency comb, as well as precise microwave time transfer
systems between space and ground. The tick rates of the clocks are continuously compared with each other, and nearly continuously
with clocks on earth, during the course of the 3-year mission. The highly elliptic orbit of the satellite is optimized for
the scientific goals, providing a large variation in the gravitational potential between perigee and apogee. Besides the fundamental
physics results, as secondary goals EGE will establish a global reference frame for the Earth’s gravitational potential and
will allow a new approach to mapping Earth’s gravity field with very high spatial resolution. The mission was proposed as
a class-M mission to ESA’s Cosmic Vision Program 2015–2025.
相似文献
| S. SchillerEmail: |
9.
D. J. Scheeres 《Celestial Mechanics and Dynamical Astronomy》1998,70(2):75-98
Starting from the four-body problem a generalization of both the restricted three-body problem and the Hill three-body problem
is derived. The model is time periodic and contains two parameters: the mass ratio ν of the restricted three-body problem
and the period parameter m of the Hill Variation orbit. In the proper coordinate frames the restricted three-body problem
is recovered as m → 0 and the classical Hill three-body problem is recovered as ν → 0. This model also predicts motions described
by earlier researchers using specific models of the Earth–Moon–Sun system. An application of the current model to the motion
of a spacecraft in the Sun perturbed Earth–Moon system is made using Hill's Variation orbit for the motion of the Earth–Moon
system. The model is general enough to apply to the motion of an infinitesimal mass under the influence of any two primaries
which orbit a larger mass.
Using the model, numerical investigations of the structure of motions around the geometric position of the triangular Lagrange
points are performed. Values of the parameter ν range in the neighborhood of the Earth–Moon value as the parameter m increases
from 0 to 0.195 at which point the Hill Variation orbit becomes unstable. Two families of planar periodic orbits are studied
in detail as the parameters m and ν vary. These families contain stable and unstable members in the plane and all have the
out-of-plane stability. The stable and unstable manifolds of the unstable periodic orbits are computed and found to be trapped
in a geometric area of phase space over long periods of time for ranges of the parameter values including the Earth–Moon–Sun
system.
This model is derived from the general four-body problem by rigorous application of the Hill and restricted approximations.
The validity of the Hill approximation is discussed in light of the actual geometry of the Earth–Moon–Sun system.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
10.
11.
This paper investigates the orbit radial stabilization of a two-craft virtual Coulomb structure about circular orbits and
at Earth–Moon libration points. A generic Lyapunov feedback controller is designed for asymptotically stabilizing an orbit
radial configuration about circular orbits and collinear libration points. The new feedback controller at the libration points
is provided as a generic control law in which circular Earth orbit control form a special case. This control law can withstand
differential solar perturbation effects on the two-craft formation. Electrostatic Coulomb forces acting in the longitudinal
direction control the relative distance between the two satellites and inertial electric propulsion thrusting acting in the
transverse directions control the in-plane and out-of-plane attitude motions. The electrostatic virtual tether between the
two craft is capable of both tensile and compressive forces. Using the Lyapunov’s second method the feedback control law guarantees
closed loop stability. Numerical simulations using the non-linear control law are presented for circular orbits and at an
Earth–Moon collinear libration point. 相似文献
12.
Using trajectory calculations of cosmic rays in the geomagnetic field, the changes of vertical cutoff rigidities in the past
are discussed. The computations are done for selected positions at the Earth’s surface using the IGRF model data for 1900–2000.
The contour maps of vertical cutoff rigidities using the set of ten Gauss coefficients for the period of years between 0 and
1600 are obtained. The trends in long-term variability of cutoffs at different positions on the Earth’s surface are described. 相似文献
13.
Thomas N. Woods Phillip C. Chamberlin W. K. Peterson R. R. Meier Phil G. Richards Douglas J. Strickland Gang Lu Liying Qian Stanley C. Solomon B. A. Iijima A. J. Mannucci B. T. Tsurutani 《Solar physics》2008,250(2):235-267
Solar soft X-ray (XUV) radiation is highly variable on all time scales and strongly affects Earth’s ionosphere and upper atmosphere;
consequently, the solar XUV irradiance is important for atmospheric studies and for space weather applications. Although there
have been several recent measurements of the solar XUV irradiance, detailed understanding of the solar XUV irradiance, especially
its variability during flares, has been hampered by the broad bands measured in the XUV range. In particular, the simple conversion
of the XUV photometer signal into irradiance, in which a static solar spectrum is assumed, overestimates the flare variations
by more than a factor of two as compared to the atmospheric response to the flares. To address this deficiency in the simple
conversion, an improved algorithm using CHIANTI spectral models has been developed to process the XUV Photometer System (XPS)
measurements with its broadband photometers. Model spectra representative of quiet Sun, active region, and flares are combined
to match the signals from the XPS and produce spectra from 0.1 to 40 nm in 0.1-nm intervals for the XPS Level 4 data product.
The two XPS instruments are aboard NASA’s Solar Radiation and Climate Experiment (SORCE) and Thermosphere, Ionosphere, Mesosphere, Energetics, and Dynamics (TIMED) satellites. In addition, the XPS responsivities have been updated for the latest XPS data processing version. The
new XPS results are consistent with daily variations from the previous simple conversion technique used for XPS and are also
consistent with spectral measurements made at wavelengths longer than 27 nm. Most importantly, the XPS flare variations are
reduced by factors of 2 – 4 at wavelengths shorter than 14 nm and are more consistent, for the first time, with atmospheric
response to solar flares. Along with the details of the new XPS algorithm, several comparisons to dayglow and photoelectron
measurements and model results are also presented to help verify the accuracy of the new XUV irradiance spectra. 相似文献
14.
In addition to the detection of an asteroid moon or a binary asteroid, the knowledge of the satellite’s true orbit is of high importance to derive fundamental physical parameters of the binary system such as its mass and to shed light on its possible formation history and dynamical evolution (prograde/retrograde orbit, large/small eccentricity or inclination, etc.). A new methodology for preliminary orbit determination of binary asteroids – and visual binaries in general – is proposed. It is based on Thiele–Innes method combined with a ‘trial and error’ Monte-Carlo technique. This method provides the full set of solutions (bundle of orbits, with the 7 orbital elements) even for a reduced number of observations. The mass is a direct by-product of this orbit determination, from which one can next infer the bulk-density and porosity. In addition to the bundle of orbits, the method provides the marginal probability densities of the foreseen parameters. Such error analysis – since it avoids linear approximation – can be of importance for the prediction of the satellite’s position in the plane-of-sky during future stellar occultations or subsequent observations, but also for the analysis of the orbit’s secular evolution. After briefly describing the method, we present the algorithm and its application to some practical cases, with particular emphasis on asteroids binaries and applications on orbital evolution. 相似文献
15.
This paper presents a Hamiltonian approach to modelling spacecraft motion relative to a circular reference orbit based on
a derivation of canonical coordinates for the relative state-space dynamics. The Hamiltonian formulation facilitates the modelling
of high-order terms and orbital perturbations within the context of the Clohessy–Wiltshire solution. First, the Hamiltonian
is partitioned into a linear term and a high-order term. The Hamilton–Jacobi equations are solved for the linear part by separation,
and new constants for the relative motions are obtained, called epicyclic elements. The influence of higher order terms and
perturbations, such as Earth’s oblateness, are incorporated into the analysis by a variation of parameters procedure. As an
example, closed-form solutions for J2-invariant orbits are obtained. 相似文献
16.
O. V. Dudnik P. Podgorski J. Sylwester S. Gburek M. Kowalinski M. Siarkowski S. Plocieniak J. Bakala 《Solar System Research》2012,46(2):160-169
A joint analysis is carried out of data obtained with the help of the solar X-ray SphinX spectrophotometer and the electron
and proton satellite telescope STEP-F in May 2009 in the course of the scientific space experiment CORONAS-PHOTON. In order
to determine the energies and particle types, in the analysis of spectrophotometer records data are used on the intensities
of electrons, protons, and secondary γ-radiation, obtained by the STEP-F telescope, which was located in close proximity to
the SphinX spectrophotometer. The identical reaction of both instruments is noted at the intersection of regions of the Brazilian
magnetic anomaly and the Earth’s radiation belts. It is shown that large area photodiodes, serving as sensors of the X-ray
spectrometer, reliably record electron fluxes of low and intermediate energies, as well as fluxes of the secondary gamma radiation
from construction materials of detector modules, the TESIS instrument complex, and the spacecraft itself. The dynamics of
electron fluxes, recorded by the SphinX spectrophotometer in the vicinity of a weak geomagnetic storm, supplements the information
about the processes of radial diffusion of electrons, which was studied using the STEP-F telescope. 相似文献
17.
Michael Efroimsky 《Celestial Mechanics and Dynamical Astronomy》2005,91(1-2):75-108
It was believed until very recently that a near-equatorial satellite would always keep up with the planet’s equator (with
oscillations in inclination, but without a secular drift). As explained in Efroimsky and Goldreich [Astronomy & Astrophysics (2004) Vol. 415, pp. 1187–1199], this misconception originated from a wrong interpretation of a (mathematically correct)
result obtained in terms of non-osculating orbital elements. A similar analysis carried out in the language of osculating
elements will endow the planetary equations with some extra terms caused by the planet’s obliquity change. Some of these terms
will be non-trivial, in that they will not be amendments to the disturbing function. Due to the extra terms, the variations
of a planet’s obliquity may cause a secular drift of its satellite orbit inclination. In this article we set out the analytical
formalism for our study of this drift. We demonstrate that, in the case of uniform precession, the drift will be extremely
slow, because the first-order terms responsible for the drift will be short-period and, thus, will have vanishing orbital
averages (as anticipated 40 years ago by Peter Goldreich), while the secular terms will be of the second order only. However,
it turns out that variations of the planetary precession make the first-order terms secular. For example, the planetary nutations
will resonate with the satellite’s orbital frequency and, thereby, may instigate a secular drift. A detailed study of this
process will be offered in a subsequent publication, while here we work out the required mathematical formalism and point
out the key aspects of the dynamics.
In this article, as well as in (Efroimsky 2004), we use the word ‘‘precession’’ in its most general sense which embraces the
entire spectrum of changes of the spin-axis orientation -- from the long-term variations down to the Chandler Wobble down
to nutations and to the polar wonder. 相似文献
18.
Michael Efroimsky 《Celestial Mechanics and Dynamical Astronomy》2006,96(3-4):259-288
We continue the study undertaken in Efroimsky [Celest. Mech. Dyn. Astron. 91, 75–108 (2005a)] where we explored the influence of spin-axis variations of an oblate planet on satellite orbits. Near-equatorial satellites had long been believed to keep up with the oblate primary’s equator in the cause of its spin-axis variations. As demonstrated by Efroimsky and Goldreich [Astron. Astrophys. 415, 1187–1199 (2004)], this opinion had stemmed from an inexact interpretation of a correct result by Goldreich [Astron. J. 70, 5–9 (1965)]. Although Goldreich [Astron. J. 70, 5–9 (1965)] mentioned that his result (preservation of the initial inclination, up to small oscillations about the moving equatorial plane) was obtained for non-osculating inclination, his admonition had been persistently ignored for forty years. It was explained in Efroimsky and Goldreich [Astron. Astrophys. 415, 1187–1199 (2004)] that the equator precession influences the osculating inclination of a satellite orbit already in the first order over the perturbation caused by a transition from an inertial to an equatorial coordinate system. It was later shown in Efroimsky [Celest. Mech. Dyn. Astron. 91, 75–108 (2005a)] that the secular part of the inclination is affected only in the second order. This fact, anticipated by Goldreich [Astron. J. 70, 5–9 (1965)], remains valid for a constant rate of the precession. It turns out that non-uniform variations of the planetary spin state generate changes in the osculating elements, that are linear in , where is the planetary equator’s total precession rate that includes the equinoctial precession, nutation, the Chandler wobble, and the polar wander. We work out a formalism which will help us to determine if these factors cause a drift of a satellite orbit away from the evolving planetary equator.By “precession,” in its most general sense, we mean any change of the direction of the spin axis of the planet—from its long-term variations down to nutations down to the Chandler wobble and polar wander. 相似文献
19.
The possibility of using a trap with ultracold neutrons as a detector of dark matter particles with long-range forces is considered.
The main advantage of the proposed method lies in the possibility of detecting a recoil energy of ∼10−7 eV. Constraints on the parameters of an interaction potential of the form φ (r) = ae
−r/b
/r between dark matter particles and a neutron are presented at various dark matter densities on Earth. The assumption about
the long-range interaction of dark matter particles and ordinary matter is shown to lead to a significant increase in the
elastic scattering cross section at low energies. As a consequence, it becomes possible to capture and accumulate dark matter
in the Earth’s gravitational field. The accumulated dark matter in the Earth’s gravitational field is roughly estimated. The
first experimental constraints on the existence of dark matter with long-range forces on Earth are presented. 相似文献
20.
This paper reports on the detection of a satellite around the principal nucleus of comet Hale-Bopp. As shown elsewhere, a
successful morphological model for the comet's dust coma necessitates the postulation of overlapping jet activity from a comet
pair. The satellite has been detected digitally on images taken with the Hubble Space Telescope's Wide Field Planetary Camera
2 in the planetary mode on five days in May–October 1996. An average satellite-to-primary signal ratio is 0.21 ± 0.03, which
implies that the satellite is ∼30 km in diameter, assuming the main nucleus is ∼70 km across. To avoid collision, the separation
distance must exceed 50–60 km at all times. The satellite's projected distances on the images vary from 160 to 210 km, or
0.06 to 0.10 arcsec. The satellite was not detected in October 1995, presumably because of its subpixel separation from the
primary. The radius of the gravitational sphere of action of the principal nucleus 70 km in diameter is 370–540 km at perihelion,
increasing linearly with the Sun's distance: the satellite appears to be in a fairly stable orbit. Its orbital period at ∼180
km is expected to be ∼2–3 days, much shorter than the intervals between the HST observations. If the main nucleus should be
no more than 42 km across, Weaver et al.'s upper limit, the satellite's orbit could become unstable, with the object drifting
away from the main nucleus after perihelion. Potentially relevant ground-based detections of close companions are reported.
Efforts to determine the satellite's orbit and the total mass of the system will get under way in the near future.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献