共查询到20条相似文献,搜索用时 31 毫秒
1.
Thierry Appourchaux Raymond Burston Yanbei Chen Michael Cruise Hansjörg Dittus Bernard Foulon Patrick Gill Laurent Gizon Hugh Klein Sergei Klioner Sergei Kopeikin Hans Krüger Claus Lämmerzahl Alberto Lobo Xinlian Luo Helen Margolis Wei-Tou Ni Antonio Pulido Patón Qiuhe Peng Achim Peters Ernst Rasel Albrecht Rüdiger Étienne Samain Hanns Selig Diana Shaul Timothy Sumner Stephan Theil Pierre Touboul Slava Turyshev Haitao Wang Li Wang Linqing Wen Andreas Wicht Ji Wu Xiaomin Zhang Cheng Zhao 《Experimental Astronomy》2009,23(2):491-527
ASTROD I is a planned interplanetary space mission with multiple goals. The primary aims are: to test general relativity with
an improvement in sensitivity of over three orders of magnitude, improving our understanding of gravity and aiding the development
of a new quantum gravity theory; to measure key solar system parameters with increased accuracy, advancing solar physics and
our knowledge of the solar system; and to measure the time rate of change of the gravitational constant with an order of magnitude
improvement and the anomalous Pioneer acceleration, thereby probing dark matter and dark energy gravitationally. It is an
international project, with major contributions from Europe and China and is envisaged as the first in a series of ASTROD
missions. ASTROD I will consist of one spacecraft carrying a telescope, four lasers, two event timers and a clock. Two-way,
two-wavelength laser pulse ranging will be used between the spacecraft in a solar orbit and deep space laser stations on Earth,
to achieve the ASTROD I goals. A second mission, ASTROD (ASTROD II) is envisaged as a three-spacecraft mission which would
test General Relativity to 1 ppb, enable detection of solar g-modes, measure the solar Lense–Thirring effect to 10 ppm, and
probe gravitational waves at frequencies below the LISA bandwidth. In the third phase (ASTROD III or Super-ASTROD), larger
orbits could be implemented to map the outer solar system and to probe primordial gravitational-waves at frequencies below
the ASTROD II bandwidth.
相似文献
Wei-Tou NiEmail: |
2.
M. Ollivier O. Absil F. Allard J.-P. Berger P. Bordé F. Cassaing B. Chazelas A. Chelli O. Chesneau V. Coudé du Foresto D. Defrère P. Duchon P. Gabor J. Gay E. Herwats S. Jacquinod P. Kern P. Kervella J.-M. Le Duigou A. Léger B. Lopez F. Malbet D. Mourard D. Pelat G. Perrin Y. Rabbia D. Rouan J.-M. Reiss G. Rousset F. Selsis P. Stee J. Surdej 《Experimental Astronomy》2009,23(1):403-434
PEGASE is a mission dedicated to the exploration of the environment (including habitable zone) of young and solar-type stars
(particularly those in the DARWIN catalogue) and the observation of low mass companions around nearby stars. It is a space
interferometer project composed of three free flying spacecraft, respectively featuring two 40 cm siderostats and a beam combiner
working in the visible and near infrared. It has been proposed to ESA as an answer to the first “Cosmic Vision” call for proposals,
as an M mission. The concept also enables full-scale demonstration of space nulling interferometry operation for DARWIN.
相似文献
M. OllivierEmail: |
3.
《Experimental Astronomy》2009,23(1):435-461
As a response to ESA call for mission concepts for its Cosmic Vision 2015–2025 plan, we propose a mission called Darwin. Its primary goal is the study of terrestrial extrasolar planets and the search for life on them. In this paper, we describe
different characteristics of the instrument.
相似文献
Charles S. CockellEmail: |
4.
A. Refregier 《Experimental Astronomy》2009,23(1):17-37
The Dark UNiverse Explorer (DUNE) is a wide-field space imager whose primary goal is the study of dark energy and dark matter
with unprecedented precision. For this purpose, DUNE is optimised for the measurement of weak gravitational lensing but will
also provide complementary measurements of baryonic accoustic oscillations, cluster counts and the Integrated Sachs Wolfe
effect. Immediate auxiliary goals concern the evolution of galaxies, to be studied with unequalled statistical power, the
detailed structure of the Milky Way and nearby galaxies, and the demographics of Earth-mass planets. DUNE is an Medium-class
mission which makes use of readily available components, heritage from other missions, and synergy with ground based facilities
to minimise cost and risks. The payload consists of a 1.2 m telescope with a combined visible/NIR field-of-view of 1 deg2. DUNE will carry out an all-sky survey, ranging from 550 to 1600 nm, in one visible and three NIR bands which will form a
unique legacy for astronomy. DUNE will yield major advances in a broad range of fields in astrophysics including fundamental
cosmology, galaxy evolution, and extrasolar planet search. DUNE was recently selected by ESA as one of the mission concepts
to be studied in its Cosmic Vision programme.
相似文献
A. RefregierEmail: |
5.
T. Appourchaux P. Liewer M. Watt D. Alexander V. Andretta F. Auchère P. D’Arrigo J. Ayon T. Corbard S. Fineschi W. Finsterle L. Floyd G. Garbe L. Gizon D. Hassler L. Harra A. Kosovichev J. Leibacher M. Leipold N. Murphy M. Maksimovic V. Martinez-Pillet B. S. A. Matthews R. Mewaldt D. Moses J. Newmark S. Régnier W. Schmutz D. Socker D. Spadaro M. Stuttard C. Trosseille R. Ulrich M. Velli A. Vourlidas C. R. Wimmer-Schweingruber T. Zurbuchen 《Experimental Astronomy》2009,23(3):1079-1117
The POLAR Investigation of the Sun (POLARIS) mission uses a combination of a gravity assist and solar sail propulsion to place
a spacecraft in a 0.48 AU circular orbit around the Sun with an inclination of 75° with respect to solar equator. This challenging
orbit is made possible by the challenging development of solar sail propulsion. This first extended view of the high-latitude
regions of the Sun will enable crucial observations not possible from the ecliptic viewpoint or from Solar Orbiter. While
Solar Orbiter would give the first glimpse of the high latitude magnetic field and flows to probe the solar dynamo, it does
not have sufficient viewing of the polar regions to achieve POLARIS’s primary objective: determining the relation between
the magnetism and dynamics of the Sun’s polar regions and the solar cycle.
相似文献
T. AppourchauxEmail: |
6.
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: |
7.
《Experimental Astronomy》2009,23(1):39-66
We describe the scientific motivations, the mission concept and the instrumentation of SPACE, a class-M mission proposed for concept study at the first call of the ESA Cosmic-Vision 2015–2025 planning cycle. SPACE aims to produce the largest three-dimensional evolutionary map of the Universe over the past 10 billion years by taking near-IR
spectra and measuring redshifts for more than half a billion galaxies at 0 < z < 2 down to AB~23 over 3π sr of the sky. In addition, SPACE will also target a smaller sky field, performing a deep spectroscopic survey of millions of galaxies to AB~26 and at 2 < z < 10 +. These goals are unreachable with ground-based observations due to the ≈500 times higher sky background (see e.g.
Aldering, LBNL report number LBNL-51157, 2001). To achieve the main science objectives, SPACE will use a 1.5 m diameter Ritchey-Chretien telescope equipped with a set of arrays of Digital Micro-mirror Devices covering
a total field of view of 0.4 deg2, and will perform large-multiplexing multi-object spectroscopy (e.g. ≈6000 targets per pointing) at a spectral resolution
of R~400 as well as diffraction-limited imaging with continuous coverage from 0.8 to 1.8 μm. Owing to the depth, redshift
range, volume coverage and quality of its spectra, SPACE will reveal with unique sensitivity most of the fundamental cosmological signatures, including the power spectrum of density
fluctuations and its turnover. SPACE will also place high accuracy constraints on the dark energy equation of state parameter and its evolution by measuring the
baryonic acoustic oscillations imprinted when matter and radiation decoupled, the distance-luminosity relation of cosmological
supernovae, the evolution of the cosmic expansion rate, the growth rate of cosmic large-scale structure, and high-z galaxy clusters. The datasets from the SPACE mission will represent a long lasting legacy for the whole astronomical community whose data will be mined for many years
to come.
相似文献
A. CimattiEmail: |
8.
《Experimental Astronomy》2009,23(1):277-302
The Molecular Hydrogen Explorer, H2EX, was proposed in response to the ESA 2015 - 2025 Cosmic Vision Call as a medium class space mission with NASA and CSA participations.
The mission, conceived to understand the formation of galaxies, stars and planets from molecular hydrogen, is designed to
observe the first rotational lines of the H2 molecule (28.2, 17.0, 12.3 and 9.7 μm) over a wide field, and at high spectral resolution. H2EX can provide an inventory of warm (≥ 100 K) molecular gas in a broad variety of objects, including nearby young star clusters,
galactic molecular clouds, active galactic nuclei, local and distant galaxies. The rich array of molecular, atomic and ionic
lines, as well as solid state features available in the 8 to 29 μm spectral range brings additional science dimensions to
H2EX. We present the optical and mechanical design of the H2EX payload based on an innovative Imaging Fourier Transform Spectrometer fed by a 1.2 m telescope. The 20’×20’ field of view
is imaged on two 1024×1024 Si:As detectors. The maximum resolution of 0.032 cm − 1 (full width at half maximum) means a velocity resolution of 10 km s − 1 for the 0 – 0 S(3) line at 9.7 μm. This instrument offers the large field of view necessary to survey extended emission in
the Galaxy and local Universe galaxies as well as to perform unbiased extragalactic and circumstellar disks surveys. The high
spectral resolution makes H2EX uniquely suited to study the dynamics of H2 in all these environments. The mission plan is made of seven wide-field spectro-imaging legacy programs, from the cosmic
web to galactic young star clusters, within a nominal two years mission. The payload has been designed to re-use the Planck platform and passive cooling design.
相似文献
J. P. Maillard (Corresponding author)Email: |
9.
XMM-Newton is a major X-ray observatory of the European Space Agency (ESA). Its observing time is open to astronomers from the whole scientific community on a peer reviewed competitive basis. The Science Operations Centre, located at ESA’s premises in Villafranca del Castillo, Spain, is responsible for the instrument operations, as well as for all the tasks related to facilitating the scientific exploitation of the data which the mission has been producing since its launch in December 1999. Among them, one may list:
Everyone can be an XMM-Newton observer. So far, astronomers from 36 countries submitted observing programs. Public data can be accessed by every scientist in the world through the XMM-Newton Science Archive (XSA).Despite all these efforts, one can’t help noticing an asymmetric level of scientific exploitation in the realm of X-ray astronomy between developing and developed countries. The latter have traditionally enjoyed the comparative advantage of deeper know-how, deriving from direct experience in hardware and mission development. The XMM-Newton Science Operations Centre’s efforts act to alleviate this situation through, for example, increasing the usage of the web for data and information dissemination, as well as by supporting actively such initiatives as the COSPAR Capacity-Building Workshops, specifically designed to create long-lasting bridges between researchers in developing and developed countries. 相似文献
• | distribution of scientific data in different formats, from raw telemetry, up to processed and calibrated high-level science products, such as images, spectra, source lists, etc; |
• | development and distribution of dedicated science analysis software, as well as of continuously updated instrument calibration; |
• | regular organisation of training workshops (free of cost), for potential users of XMM-Newton data, where the procedures and techniques to successfully reduce and analyze XMM-Newton data are introduced; |
• | access to the data through state-of-the-art, in-house-developed archival facilities, either through the Internet or via CD-ROM; |
• | continuously updated documentation on all aspects of spacecraft and instrument operations, data reduction and analysis; |
• | maintenance of a comprehensive set of project web pages; |
• | a competent and responsive HelpDesk, providing dedicated support to individual XMM-Newton users. |
10.
K. B. Bhatnagar Usha Gupta Rashmi Bhardwaj 《Celestial Mechanics and Dynamical Astronomy》1994,59(4):345-374
The non-linear stability of the libration pointL
4 in the restricted problem has been studied when there are perturbations in the potentials between the bodies. It is seen that the pointL
4 is stable for all mass ratios in the range of linear stability except for three mass ratios depending upon the perturbing functions. The theory is applied to the following four cases:
相似文献
(i) | There are no perturbations in the potentials (classical problem). |
(ii) | Only the bigger primary is an oblate spheroid whose axis of symmetry is perpendicular to the plane of relative motion (circular) of the primaries. |
(iii) | Both the primaries are oblate spheroids whose axes of symmetry are perpendicular to the plane of relative motion (circular) of the primaries. |
(iv) | The primaries are spherical in shape and the bigger is a source of radiation. |
11.
The main goal of this paper is to compare the relative importance of destruction by tides vs. destruction by mergers, in order to assess if tidal destruction of galaxies in clusters is a viable scenario for explaining
the origin of intracluster stars. We have designed a simple algorithm for simulating the evolution of isolated clusters. The
distribution of galaxies in the cluster is evolved using a direct gravitational N-body algorithm combined with a subgrid treatment of physical processes such as mergers, tidal disruption, and galaxy harassment.
Using this algorithm, we have performed a total of 148 simulations. Our main results are:
相似文献
– | destruction of dwarf galaxies by mergers dominates over destruction by tides, and |
– | the destruction of galaxies by tides is sufficient to explain the observed intracluster light in clusters. |
12.
The Earth's gravitational potential is now usually expressed in terms of a double series of tesseral harmonics with several hundred terms, up to order and degree at least 20. The harmonics of order 14 can be evaluated by analysing changes in satellite orbits which experience 14th-order resonance, when the track over the Earth repeats after 14 revolutions.In this paper we describe our first evaluation of individual 14th-order coefficients in the geopotential from analysis of the variations in inclination and eccentricity of satellite orbits passing through 14th-order resonance under the action of air drag. Using results from eleven satellites, we find the following values for normalized coefficients of harmonics of order 14 and degree l, C?l, 14 and S?l, 14, for l=14, 154. 22:
109C? | 109S?l,14 | |
- | - | - |
14 | ?38.5 ±2.9 | ?7.8 ±2.2 |
15 | 4.5 ±1.1 | ?23.8 ±0.3 |
16 | ?22.3 ±3.6 | ?36.0 ±3.8 |
17 | ?15.0 ±2.6 | 16.8 ±1.2 |
18 | ?24.0±4.9 | ?3.2 ±3.7 |
19 | ?1.6 ±2.8 | ?7.6 ±1.0 |
20 | 8.8 ±5.8 | ?15.4 ±4.6 |
21 | 18.2 ±3.6 | ?10.6 ±1.9 |
22 | ?14.5 ±8.1 | 9.9 ±6.4 |
| - the r.m.s. difference between the positions is 1.1 cm; |
| - the r.m.s. difference between the ranges is 0.5 cm. |
14.
The purpose of this paper is to find correlation between OI 6300 Å line intensity with solar and ionospheric parameters. A critical study have been made and the following important results are obtained:
相似文献
(i) | Solar flare index plays more important role for the emissions of 6300 Å line than other solar parameters. |
(ii) | Intensity of 6300 Å line increases linearly with the increase of solar flare index. |
(iii) | Virtual height plays more important role than critical frequency for the emission of 6300 Å line-intensity. |
(iv) | Possible explanation of this type of variation is also presented. |
15.
Doreen M. C. Walker 《Planetary and Space Science》1975,23(12):1573-1579
Explorer 1, 1958α, ths first U.S. artificial satellite, was launched on 1 February 1958 and remained in orbit for 12 years. In this paper theoretical curves have been fitted to the values of inclination, giving three values of the average atmospheric rotation rate at heights of 350–400 km, and latitudes 0–20°:
Feb 1958 to mid 1960 | 1.5 rev/day | |
Mid 1960 to Dec 1967 | 1.2 rev/day | |
Jan 1968 to Mar 1970 | 1.3 rev/day |
(1) | Eleven years, 6 and 3 months for the solar wind streamers, which have solar flares as sources. |
(2) | Fourteen years and 36, 24, 12, 6, 4, 3 months for the number of solar wind streamers, which have coronal holes as sources. |
(3) | Sixteen years for the total number of solar wind streamers. |
17.
When a satellite orbit decaying slowly under the action of air drag experiences 15th-order resonance with the Earth's gravitational field, so that the ground track repeats after 15 rev, the orbital inclination suffers appreciable changes due to the perturbations from the harmonics in the geopotential of order 15 and odd degree (15,17,19 …). In this paper the changes in inclination at resonance of 11 satellites at inclinations between 30° and 90° have been analysed to determine values of the geopotential coefficients of order 15 and degree and in the usual notation. The recommended solution, going up to l = 31, is:
l | 109C?l,15 | 109S?l,15 |
15 | ?21.5 ± 0.9 | ?8.4 ± 0.9 |
17 | 4.4 ± 1.6 | 9.0 ± 1.5 |
19 | ?15.6 ± 2.6 | ?14.1 ± 2.7 |
21 | 10.4 ± 3.0 | 7.3 ± 3.5 |
23 | 22.5 ± 2.8 | 1.2 ± 4.4 |
25 | ?0.9 ± 4.7 | ?3.8 ± 5.3 |
27 | ?11.2 ±3.3 | 9.1 ± 3.2 |
29 | ?20.5 ± 5.4 | ?1.2 ± 6.1 |
31 | 17.7 ± 6.6 | ?1.0 ± 7.1 |
l | 109C?l,15 | 109S?l,15 |
15 | ?23.5 ± 0.8 | ?7.7 ± 0.8 |
17 | 6.3 ± 1.5 | 5.6 ± 1.5 |
19 | ?25.1 ± 2.5 | ?7.3 ± 2.3 |
21 | 27.8 ± 3.6 | ?0.7 ± 3.4 |
23 | 17.1 ± 4.1 | 13.9 ± 4.8 |
25 | ?1.1 ± 3.0 | 8.5 ± 4.2 |
27 | 10.0 ± 3.3 | 6.7 ± 2.7 |
29 | ?9.4 ± 3.5 | 0.1 ± 4.7 |
31 | 10.1 ± 5.4 | 3.8 ± 5.6 |
33 | 1.1 ± 5.7 | 3.1 ± 5.8 |
109 | 109 | |
16 | ?13.7 ± 1.3 | ?18.5 ± 2.7 |
18 | ?42.3 ± 1.8 | ?34.7 ± 3.4 |
20 | 10.5 ± 3.1 | 29.8 ± 5.2 |
22 | ?8.6 ± 3.8 | ?20.2 ± 7.4 |
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