共查询到20条相似文献，搜索用时 23 毫秒
1.
Bert L. A. Vermeersen 《Earth, Moon, and Planets》2004,94(1-2):31-40
Examples from four main categories of solid-earth deformation processes are discussed for which the GOCE and GRACE satellite
gravity missions will not provide a high enough spatial or temporal resolution or a sufficient accuracy. Quasi-static and
episodic solid-earth deformation would benefit from a new satellite gravity mission that would provide a higher combined spatial
and temporal resolution. Seismic and core periodic motions would benefit from a new satellite mission that would be able to
detect gravity variations with a higher temporal resolution combined with very high accuracies. 相似文献
2.
After GRACE and GOCE there will still be need and room for improvement of the knowledge (1) of the static gravity field at
spatial scales between 40 km and 100 km, and (2) of the time varying gravity field at scales smaller than 500 km. This is
shown based on the analysis of spectral signal power of various gravity field components and on the comparison with current
knowledge and expected performance of GRACE and GOCE. Both, accuracy and resolution can be improved by future dedicated gravity
satellite missions. For applications in geodesy, the spectral omission error due to the limited spatial resolution of a gravity
satellite mission is a limiting factor. The recommended strategy is to extend as far as possible the spatial resolution of
future missions, and to improve at the same time the modelling of the very small scale components using terrestrial gravity
information and topographic models.We discuss the geodetic needs in improved gravity models in the areas of precise height
systems, GNSS levelling, inertial navigation and precise orbit determination. Today global height systems with a 1 cm accuracy
are required for sea level and ocean circulation studies. This can be achieved by a future satellite mission with higher spatial
resolution in combination with improved local and regional gravity field modelling. A similar strategy could improve the very
economic method of determination of physical heights by GNSS levelling from the decimeter to the centimeter level. In inertial
vehicle navigation, in particular in sub-marine, aircraft and missile guidance, any improvement of global gravity field models
would help to improve reliability and the radius of operation. 相似文献
3.
The importance of an accurate model of the Moon gravity field has been assessed for future navigation missions orbiting and/or
landing on the Moon, in order to use our natural satellite as an intermediate base for next solar system observations and
exploration as well as for lunar resources mapping and exploitation. One of the main scientific goals of MAGIA mission, whose
Phase A study has been recently funded by the Italian Space Agency (ASI), is the mapping of lunar gravitational anomalies,
and in particular those on the hidden side of the Moon, with an accuracy of 1 mGal RMS at lunar surface in the global solution
of the gravitational field up to degree and order 80. MAGIA gravimetric experiment is performed into two phases: the first
one, along which the main satellite shall perform remote sensing of the Moon surface, foresees the use of Precise Orbit Determination
(POD) data available from ground tracking of the main satellite for the determination of the long wavelength components of
gravitational field. Improvement in the accuracy of POD results are expected by the use of ISA, the Italian accelerometer
on board the main satellite. Additional gravitational data from recent missions, like Kaguya/Selene, could be used in order
to enhance the accuracy of such results. In the second phase the medium/short wavelength components of gravitational field
shall be obtained through a low-to-low (GRACE-like) Satellite-to-Satellite Tracking (SST) experiment. POD data shall be acquired
during the whole mission duration, while the SST data shall be available after the remote sensing phase, when the sub-satellite
shall be released from the main one and both satellites shall be left in a free-fall dynamics in the gravity field of the
Moon. SST range-rate data between the two satellites shall be measured through an inter-satellite link with accuracy compliant
with current state of art space qualified technology. SST processing and gravitational anomalies retrieval shall benefit from
a second ISA accelerometer on the sub-satellite in order to decouple lunar gravitational signal from other accelerations.
Experiment performance analysis shows that the stated scientific requirements can be achieved with a low mass and low cost
sub-satellite, with a SST gravimetric mission of just few months. 相似文献
4.
R. Rummel 《Earth, Moon, and Planets》2004,94(1-2):3-11
Precise global geoid and gravity anomaly information serves essentially three different kinds of applications in Earth sciences:
gravity and geoid anomalies reflect density anomalies in oceanic and continental lithosphere and the mantle; dynamic ocean
topography as derived from the combination of satellite altimetry and a global geoid model can be directly transformed into
a global map of ocean surface circulation; any redistribution or exchange of mass in Earth system results in temporal gravity
and geoid changes. After completion of the dedicated gravity satellite missions GRACE and GOCE a high standard of global gravity
determination, both of the static and of the time varying field will be attained. Thus, it is the right time to investigate
the future needs for improvements in the various fields of Earth sciences and to define the right strategy for future gravity
field satellite missions. 相似文献
5.
J. Flury 《Earth, Moon, and Planets》2004,94(1-2):83-91
An overview of advances in ice research which can be expected from future satellite gravity missions is given. We compare
present and expected future accuracies of the ice mass balance of Antarctica which might be constrained to 0.1–0.3 mm/year
of sea level equivalent by satellite gravity data. A key issue for the understanding of ice mass balance is the separation
of secular and interannual variations. For this aim, one would strongly benefit from longer uninterrupted time series of gravity
field variations (10 years or more). An accuracy of 0.01 mm/year for geoid time variability with a spatial resolution of 100
km would improve the separability of ice mass balance from mass change due to glacial isostatic adjustment and enable the
determination of regional variations in ice mass balance within the ice sheets. Thereby the determination of ice compaction
is critical for the exploitation of such high accuracy data. A further benefit of improved gravity field models from future
satellite missions would be the improvement of the height reference in the polar areas, which is important for the study of
coastal ice processes. Sea ice thickness determination and modelling of ice bottom topography could be improved as well. 相似文献
6.
Ernst J. O. Schrama 《Earth, Moon, and Planets》2004,94(1-2):143-163
Purpose of this article is to demonstrate the effect of background geophysical corrections on a follow-on gravity mission.
We investigate the quality of two effects, tides and atmospheric pressure variations, which both act as a surface load on
the lithosphere. In both cases direct gravitational attraction of the mass variations and the secondary potential caused by
the deformation of the lithosphere are sensed by a gravity mission. In order to assess the current situation we have simulated
GRACE range-rate errors which are caused by differences in present day tide and atmospheric pressure correction models. Both
geophysical correction models are capable of generating range-rate errors up to 10 μm/s and affect the quality of the recovered temporal and static gravity fields. Unlike missions such as TOPEX/Poseidon where
tides can be estimated with the altimeter, current gravity missions are only to some degree capable of resolving these (geo)physical
limitations. One of the reasons is the use of high inclination low earth orbits without a repeating ground track strategy.
The consequence is that we will face a contamination of the gravity solution, both in the static and the time variable part.
In the conclusions of this paper we provide suggestions for improving this situation, in particular in view of follow-on gravity
missions after GRACE and GOCE, which claim an improved capability of estimating temporal variations in the Earth’s gravity
field. 相似文献
7.
8.
Riccardo Claudi 《Astrophysics and Space Science》2010,328(1-2):319-323
The satellite PLATO represents a new challenge for future investigations of exoplanets and oscillations of stars. It is one of the proposed missions of ESA COSMIC VISION 2015–2025 and it is scheduled for launch in 2017. The goal of the mission is a full characterization of the planet star systems with an asteroseismic analysis of the host stars. The PLATO Payload Consortium (PPLC) includes several European countries which are employed in the assessment study of the mission. Thanks to the high precision photometry, PLATO is thought to be able to detect planets and oscillations within a large sample of targets. 相似文献
9.
John C. Niehoff 《Icarus》1977,31(4):430-438
The recent discovery of 1976 AA has renewed interest in the possibility of modest asteroid sample-return missions. Such ventures may be logical precursors to more complex round-trip planetary missions. Both manned and unmanned mission requirements are assessed for two Apollo-Amor objects: 1976 AA and 1973 EC. It is shown that the propulsion requirements of 1-yr manned missions to either target are excessive, i.e., more than 20 Shuttle launches would be required. However, a low-energy 3-yr unmanned round-trip mission to 1973 EC has also been found, which requires only one Shuttle launch with a recoverable upperstage. It is apparent from these results that the discovery of a short-period low-obliquity object could have a profound impact on man's initial ventures beyond Earth-Moon space. 相似文献
10.
Giancarmine Fasano Marco D’Errico 《Celestial Mechanics and Dynamical Astronomy》2009,105(1-3):113-139
While trajectory design for single satellite Earth observation missions is usually performed by means of analytical and relatively simple models of orbital dynamics including the main perturbations for the considered cases, most literature on formation flying dynamics is devoted to control issues rather than mission design. This work aims at bridging the gap between mission requirements and relative dynamics in multi-platform missions by means of an analytical model that describes relative motion for satellites moving on near circular low Earth orbits. The development is based on the orbital parameters approach and both the cases of close and large formations are taken into account. Secular Earth oblateness effects are included in the derivation. Modeling accuracy, when compared to a nonlinear model with two body and J2 forces, is shown to be of the order of 0.1% of relative coordinates for timescales of hundreds of orbits. An example of formation design is briefly described shaping a two-satellite formation on the basis of geometric requirements for synthetic aperture radar interferometry. 相似文献
11.
Lunar occultation can be considered of interest for future missions dedicated to X-ray astronomy only if instruments with a large enough collecting area are used. In this case, observations of the numerous, faint X-ray sources occulted by the moon during a typical satellite lifetime of several years, can, in principle, add good source positioning as a free bonus to a high-throughput, medium-imaging mission. In the practical case of the EPIC instrument aboard the XMM ESA satellite, a simple calculation shows the potential usefulness of this technique. 相似文献
12.
P. Legrand 《Earth, Moon, and Planets》2004,94(1-2):57-71
The quasi-permanent sea surface slope, i.e. the signature of oceanic currents that does not vanish when dynamic topography
observations are averaged over a long period of time, will be resolved up to spatial scales of about 100 km by the GOCE space
gravity mission. However, estimates of the quasi-permanent ocean dynamic topography, derived qualitatively either from models
or from observations, indicate that some non-negligible residual signal remains below 100 km in areas of strong surface currents
like the core of the Gulf Stream. One therefore expects that future missions can improve our knowledge of the ocean circulation
in these areas. However, the potential improvements are small compared to the improvements expected from GOCE itself. 相似文献
13.
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
14.
木星探测轨道分析与设计 总被引：3，自引：0，他引：3
研究了与木星探测相关的轨道设计问题.重点关注木星探测轨道与火星、金星等类地行星探测轨道的不同及由此带来的轨道设计难点.首先分析了绕木星探测任务轨道的选择.建立近似模型讨论了向木星飞行需要借助多颗行星的多次引力辅助,对地木转移的多种行星引力辅助序列,使用粒子群算法搜索了2020年至2025年之间的燃料最省飞行方案并对比得到了向木星飞行较好的引力辅助方式为金星-地球-地球引力辅助.结合多任务探测,研究了航天器在飞向木星途中穿越主小行星带飞越探测小行星的轨道设计.最后,给出2023年发射完整的结合引力辅助与小行星多次飞越的木星探测轨道设计算例. 相似文献
15.
S. Turck-Chièze P. Lamy C. Carr P. H. Carton A. Chevalier I. Dandouras J. M. Defise S. Dewitte T. Dudok de Wit J. P. Halain S. Hasan J. F. Hochedez T. Horbury P. Levacher M. Meissonier N. Murphy P. Rochus A. Ruzmaikin W. Schmutz G. Thuillier S. Vivès 《Experimental Astronomy》2009,23(3):1017-1055
The DynaMICCS mission is designed to probe and understand the dynamics of crucial regions of the Sun that determine solar
variability, including the previously unexplored inner core, the radiative/convective zone interface layers, the photosphere/chromosphere
layers and the low corona. The mission delivers data and knowledge that no other known mission provides for understanding
space weather and space climate and for advancing stellar physics (internal dynamics) and fundamental physics (neutrino properties,
atomic physics, gravitational moments...). The science objectives are achieved using Doppler and magnetic measurements of
the solar surface, helioseismic and coronographic measurements, solar irradiance at different wavelengths and in-situ measurements
of plasma/energetic particles/magnetic fields. The DynaMICCS payload uses an original concept studied by Thalès Alenia Space
in the framework of the CNES call for formation flying missions: an external occultation of the solar light is obtained by
putting an occulter spacecraft 150 m (or more) in front of a second spacecraft. The occulter spacecraft, a LEO platform of
the mini sat class, e.g. PROTEUS, type carries the helioseismic and irradiance instruments and the formation flying technologies.
The latter spacecraft of the same type carries a visible and infrared coronagraph for a unique observation of the solar corona
and instrumentation for the study of the solar wind and imagers. This mission must guarantee long (one 11-year solar cycle)
and continuous observations (duty cycle > 94%) of signals that can be very weak (the gravity mode detection supposes the measurement
of velocity smaller than 1 mm/s). This assumes no interruption in observation and very stable thermal conditions. The preferred
orbit therefore is the L1 orbit, which fits these requirements very well and is also an attractive environment for the spacecraft
due to its low radiation and low perturbation (solar pressure) environment. This mission is secured by instrumental R and
D activities during the present and coming years. Some prototypes of different instruments are already built (GOLFNG, SDM)
and the performances will be checked before launch on the ground or in space through planned missions of CNES and PROBA ESA
missions (PICARD, LYRA, maybe ASPIICS). 相似文献
16.
Delta-v requirements for earth co-orbital rendezvous missions 总被引：1，自引：0，他引：1
Earth co-orbital asteroids present advantages as potential targets for future asteroid rendezvous missions. Their prolonged proximity to Earth facilitates communication, while their Earth-like orbits mean a steady flux of solar power and no significant periodic heating and cooling of the spacecraft throughout the course of the mission. Theoretical studies show that low-inclination co-orbital orbits are more stable than high-inclination orbits. As inclination is the most significant indicator of low delta-v rendezvous orbits, there is the potential for a large population of easily accessible asteroids, with favorable engineering requirements. This study first looks at phase-independent rendezvous orbits to a large number of objects, then looks in more detail at the phase-dependent orbits to the most favorable objects. While rendezvous orbits to co-orbital objects do not have a low delta-v necessarily, some objects present energy requirements significantly less than previous rendezvous missions. Currently we find no ideal co-orbital asteroids for rendezvous missions, although theoretical Earth Trojans present very low-energy requirements for rendezvous. 相似文献
17.
Sandip K. Chakrabarti Ritabrata Sarkar Debashis Bhowmick Arnab Bhattacharya 《Experimental Astronomy》2017,43(3):311-338
Indian Centre for Space Physics has taken a novel strategy to study low energy cosmic rays and astrophysical X-ray sources which involve very light weight payloads up to about five kilograms on board a single or multiple balloons which are used for meteorological purposes. The mission duration could be anywhere from 3-12 hours. Our strategy provides extreme flexibility in mission preparation and its operation using a very economical budget. There are several limitations but our innovative approach has been able to extract significant amount of scientific data out of these missions. So far, over one hundred missions have been completed by us to near space and a wealth of data has been collected. The payloads are recovered and are used again. Scientific data is stored on board computer and the atmospheric data or payload location is sent to ground in real time. Since each mission is different, we present here the general strategy for a typical payload and provide some results we obtained in some of these missions. 相似文献
18.
Glenn S. Orton 《Earth, Moon, and Planets》2009,105(2-4):143-152
This report presents both a retrospective of ground-based support for spacecraft missions to the outer solar system and a perspective of support for future missions. Past support is reviewed in a series of case studies involving the author. The most basic support is essential, providing the mission with information without which the planned science would not have been accomplished. Another is critical, without which science would have been returned, but missing a key element in its understanding. Some observations are enabling by accomplishing one aspect of an experiment which would otherwise not have been possible. Other observations provide a perspective of the planet as a whole which is not available to instruments with narrow fields of view and limited spatial coverage, sometimes motivating a re-prioritizing of experiment objectives. Ground-based support is also capable of providing spectral coverage not present in the complement of spacecraft instruments. Earth-based observations also have the capability of filling in gaps of spacecraft coverage of atmospheric phenomena, as well as providing surveillance of longer-term behavior than the coverage available to the mission. Future missions benefiting from ground-based support would include the Juno mission to Jupiter in the next decade, a flagship-class mission to the Jupiter or to the Saturn systems currently under consideration, and possible intermediate-class missions which might be proposed in NASA’s New Frontiers category. One of the principal benefits of future 30 m-class giant telescopes would be to improve the spatial resolution of maps of temperature and composition which are derived from observations of thermal emission at mid-infrared and longer wavelengths. In many situations, this spatial resolution is competitive with those of the relevant instruments on the spacecraft themselves. 相似文献
19.
R. Rummel 《Earth, Moon, and Planets》2004,94(1-2):103-111
Planetology serves the understanding on the one hand of the solar system and on the other hand, for investigating similarities
and differences, of our own planet. While observational evidence about the outer planets is very limited, substantial datasets
exist for the terrestrial planets. Radar and optical images and detailed models of gravity and topography give an impressive
insight into the history, composition and dynamics of moon and planets. However, there exists still significant lack of data.
It is therefore recommended to equip all future satellite missions to the moon and to planets with full tensor gravity gradiometers
and radar altimeters. 相似文献
20.
The most significant findings about the Moon obtained by spacecraft so far, have resulted from measurements of gravity, electromagnetic properties, seismicity, mechanical properties, geologic features, composition, ages, and the lunar environment. A number of major lunar questions remain to be answered. Other properties, measurable with spacecraft, which may provide data critical to answering these questions include geometrical shape, motions, and heat flow. In this paper specific measurements that should provide critical data for each of these questions are identified, with some candidate techniques. Among the suggested techniques that have not yet been used are very long baseline interferometry (Earth-Moon baseline), gravity gradiometry, elemental analysis by neutron interactions, and remotely-controlled on-Moon microscopy.Different kinds of missions are suitable for the different measurements: lunar orbiters, soft-landers, long-range surface traverses, and sample return to Earth are all needed. The choice of manned vs remotely-controlled missions does not depend on scientific requirements but on other considerations. Both manned and remotely-controlled techniques have been used for orbiters, landers, and sample return, neither for a long-range traverse.Paper presented to the NATO Advanced Study Institute on Lunar Studies, Patras, Greece, September 1971. 相似文献