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1.
The launch of ESA's Rosetta mission, to orbit and land on a comet, has been postponed and the target of the mission may have to change. Uncertainty over the mission provoked extra interest at the RAS discussion meeting in December 2002, as Geraint Jones and Simeon Barber report. 相似文献
2.
The SWOT Mission and Its Capabilities for Land Hydrology 总被引：2，自引：0，他引：2
Sylvain Biancamaria Dennis P. Lettenmaier Tamlin M. Pavelsky 《Surveys in Geophysics》2016,37(2):307-337
3.
The Venus Express mission, currently orbiting Earth's nearest planetary neighbour, has just had its mission extended until the end of 2012 by the European Space Agency (ESA). In December 2010 it will be joined by the Japanese Venus Climate Orbiter, which has similar goals of understanding the atmosphere and climate. In this article Fred Taylor looks at what has been learned so far and what remains mysterious about our nearby twin, with its torrid weather and its global warming issues. 相似文献
4.
Ernst Hauber and Gerhard Neukum present a new perspective on the martian surface on the basis of two years of observations by the High resolution Stereo Camera, part of ESA's Mars Express mission.
All HRSC images shown are copyright ESA/DLR/FU Berlin (G Neukum). 相似文献
All HRSC images shown are copyright ESA/DLR/FU Berlin (G Neukum). 相似文献
5.
The satellite mission GOCE (Gravity Field and Steady-State Ocean Circulation Explorer), the first Core Mission of the Earth Explorer Programme funded by ESA (European Space Agency), is dedicated to the precise modelling of the Earth's gravity field, with its launch planned for 2006. The mathematical models for parameterizing the Earth's gravity field are based on a series expansion into spherical harmonics, yielding a huge number of unknown coefficients. Their computation leads to the solution of very large normal equation systems. An efficient way to handle these equation systems is the so-called semianalytic or lumped coefficients approach, which theoretically requires an uninterrupted, continuous time series of observations, recorded along an exact circular repeat orbit. In this paper the consequences of violating these conditions are analyzed. The effects of an interrupted observation stream onto the estimated spherical harmonic coefficients are demonstrated, and an iterative strategy, which reduces the negative influence depending on the characteristics of the data gaps, is proposed. Additionally, the impact of an imperfectly closing orbit (non-repeat orbit) on the gravity field model is analyzed, and a strategy to minimize the corresponding errors is presented. The applicability of the semianalytic approach also to a joint inversion of satellite-to-satellite tracking data in high-low mode (hl-SST) and satellite gravity gradiometry (SGG) observations is demonstrated, where the analysis of the former component is based on the energy conservation law. Several realistic case studies prove that the semianalytic approach is a feasible tool to generate quick-look gravity solutions, i.e. fast coefficient estimates using only partial data sets. This quick-look analysis shall be able to detect potential distortions of statistical significance (e.g. systematic errors) in the input data, and to give a fast feedback to the GOCE mission control. 相似文献
6.
The ESA Gravity and steady state Ocean and Circulation Explorer, GOCE, mission will utilise the principle of satellite gravity gradiometry to measure the long to medium wavelengths in the static gravity field. Previous studies have demonstrated the low sensitivity of GOCE to ocean tides and to temporal gravity field variations at the seasonal scale. In this study we investigate the sensitivity of satellite gradiometry missions such as GOCE to secular signals due to ice-mass change observed in Greenland and Antarctica. We show that unaccounted ice-mass change signal is likely to increase GOCE-related noise but that the expected present-day polar ice-mass change is below the GOCE sensitivity for an 18-month mission. Furthermore, 2–3 orders of magnitude improvement in the gradiometry in future gradiometer missions is necessary to detect ice-mass change with sufficient accuracy at the spatial resolution of interest. 相似文献
7.
《Journal of Geodynamics》2009,47(3-5):174-181
The Earth’s asthenosphere and lower continental crust can regionally have viscosities that are one to several orders of magnitude smaller than typical mantle viscosities. As a consequence, such shallow low-viscosity layers could induce high-harmonic (spherical harmonics 50–200) gravity and geoid anomalies due to remaining isostasy deviations following Late-Pleistocene glacial isostatic adjustment (GIA). Such high-harmonic geoid and gravity signatures would depend also on the detailed ice and meltwater loading distribution and history.ESA’s Gravity field and steady-state Ocean Circulation Explorer (GOCE) satellite mission, planned for launch in Summer 2008, is designed to map the quasi-static geoid with centimeter accuracy and gravity anomalies with milligal accuracy at a resolution of 100 km or better. This might offer the possibility of detecting gravity and geoid effects of low-viscosity shallow earth layers and differences of the effects of various Pleistocene ice decay scenarios. For example, our predictions show that for a typical low-viscosity crustal zone GOCE should be able to discern differences between ice-load histories down to length scales of about 150 km.One of the major challenges in interpreting such high-harmonic, regional-scale, geoid signatures in GOCE solutions will be to discriminate GIA-signatures from various other solid-earth contributions. It might be of help here that the high-harmonic geoid and gravity signatures form quite characteristic 2D patterns, depending on both ice load and low-viscosity zone model parameters. 相似文献
8.
本文首先概要地介绍了国际与日共存（International Living With a Star, ILWS）计划的目的、组织机构及ILWS第一次和第二次工作会议的情况.中国国家航天局于2003年4月正式参加了ILWS计划,并参加第一次和第二次工作会议.中方代表在会上提出了中国参加ILWS的建议,报告了中国新提出的“空间风暴探测计划”.现双星计划已被列为2006年以前的ILWS项目,“空间风暴探测计划”已被列为ILWS第一阶段的重要项目.本文概要地介绍了空间风暴探测计划项目的需求,主要目标和研究内容,有效载荷、轨道方案以及空间风暴计划的进度计划等. 相似文献
9.
GRACE重力卫星任务即将结束,后续GRACE Follow-On卫星计划于2017年发射,在此期间,迫切需要一个新的卫星计划继续对全球时变重力场进行连续监测,以保证时变重力场信息时间序列的连贯性.SWARM计划包括三颗轨道高为300~500 km的近极轨卫星星座,类似于三颗CHAMP卫星,具有接替时变重力场探测的潜力.本文首先分析SWARM(模拟)、CHAMP、GRACE反演至60阶时变重力场球谐系数的误差特性及不同高斯平滑半径对高频误差的抑制效果,然后分别利用SWARM、CHAMP、GRACE的时变重力场模型恢复全球质量变化,结果表明,SWARM模拟观测数据的高频误差低于CHAMP观测数据,探测时变重力场的整体精度优于CHAMP,略低于GRACE探测精度;其次,对比2003年1月—2009年12月期间CHAMP(hl-SST)和GRACE(ll-SST)时变重力场模型反演格陵兰岛冰盖质量变化趋势,结果显示,CHAMP数据得到格陵兰岛冰盖质量变化趋势为-50.2±2.0 Gt/a,GRACE所得结果为-41.2±1.6 Gt/a,两者相差21.8%;最后,对比2000年1月—2004年12月间SWARM模拟数据和"真实"模型数据反演的格陵兰岛冰盖质量变化趋势,结果表明,两者相差19.2%.本文研究表明,利用SWARM hl-SST数据探测时变重力场可以达到20%相对精度水平,有潜力用于填补GRACE和GRACE Follow-On期间探测地球时变重力场的空白. 相似文献
10.
M. Ablain J. F. Legeais P. Prandi M. Marcos L. Fenoglio-Marc H. B. Dieng J. Benveniste A. Cazenave 《Surveys in Geophysics》2017,38(1):7-31
Since the beginning of the 1990s, sea level is routinely measured using high-precision satellite altimetry. Over the past ~25 years, several groups worldwide involved in processing the satellite altimetry data regularly provide updates of sea level time series at global and regional scales. Here we present an ongoing effort supported by the European Space Agency (ESA) Climate Change Initiative Programme for improving the altimetry-based sea level products. Two main objectives characterize this enterprise: (1) to make use of ESA missions (ERS-1 and 2 and Envisat) in addition to the so-called ‘reference’ missions like TOPEX/Poseidon and the Jason series in the computation of the sea level time series, and (2) to improve all processing steps in order to meet the Global Climate Observing System (GCOS) accuracy requirements defined for a set of 50 Essential Climate Variables, sea level being one of them. We show that improved geophysical corrections, dedicated processing algorithms, reduction of instrumental bias and drifts, and careful linkage between missions led to improved sea level products. Regarding the long-term trend, the new global mean sea level record accuracy now approaches the GCOS requirements (of ~0.3 mm/year). Regional trend uncertainty has been reduced by a factor of ~2, but orbital and wet tropospheric corrections errors still prevent fully reaching the GCOS accuracy requirement. Similarly at the interannual time scale, the global mean sea level still displays 2–4 mm errors that are not yet fully understood. The recent launch of new altimetry missions (Sentinel-3, Jason-3) and the inclusion of data from currently flying missions (e.g., CryoSat, SARAL/AltiKa) may provide further improvements to this important climate record. 相似文献
11.
Neil Arnold 《Astronomy& Geophysics》2004,45(1):1.27-1.28
The London MIST meeting in November covered current research using satellites to investigate planetary environments across the solar system, including our own. Earth-bound instruments, GPS and modelling also came under discussion, as did a series of results from the Cluster mission. Neil Arnold reports. 相似文献
12.
Georg F. Zellmer Tobias P. Fischer Chang-Hwa Chen 《Journal of Volcanology and Geothermal Research》2008
In this introduction, recent progress in the study of the evolution, transfer and release of magmas and volcanic gases is briefly reviewed, based on discussions at the MAG2007 international conference held in Taipei, Taiwan, in April 2007. The meeting pooled the diverse expertise of igneous and volcanic gas geochemists. This special issue, which presents six case studies covering a range of topics from variations in mantle source compositions to the nature of volcanic degassing, reflects that diversity. 相似文献
13.
Mike Hapgood 《Astronomy& Geophysics》2002,43(1):1.26-1.26
On 9 November 2001 RAS hosted the first UK meeting to discuss results from Cluster, itself the first mission to explore the Earth's magnetosphere with four identically instrumented spacecraft – and thus fully resolve the complex spatial and temporal variations of the plasmas that fill space around the Earth. Mike Hapgood reports. 相似文献
14.
The European Gravity Field and Steady-State Ocean Circulation Explorer Satellite Mission Its Impact on Geophysics 总被引：1，自引：0，他引：1
J. A. Johannessen G. Balmino C. Le Provost R. Rummel R. Sabadini H. Sünkel C.C. Tscherning P. Visser P. Woodworth C. Hughes P. Legrand N. Sneeuw F. Perosanz M. Aguirre-Martinez H. Rebhan M. Drinkwater 《Surveys in Geophysics》2003,24(4):339-386
Current knowledge of the Earth's gravity field and its geoid, as derived from various observing techniques and sources, is incomplete. Within a reasonable time, substantial improvement will come by exploiting new approaches based on spaceborne gravity observation. Among these, the European Space Agency (ESA) Gravity field and steady-state Ocean Circulation Explorer (GOCE) satellite mission concept has been conceived and designed taking into account multi-disciplinary research objectives in solid Earth physics, oceanography and geodesy. Based on the unique capability of a gravity gradiometer combined with satellite-to-satellite high-low tracking techniques, an accurate and detailed global model of the Earth's gravity field and its corresponding geoid will be recovered. The importance of this is demonstrated by a series of realistic simulation experiments. In particular, the quantitative impact of the new and accurate gravity field and geoid is examined in studies of tectonic composition and motion, Glaciological Isostatic Adjustment, ocean mesoscale variability, water mass transport, and unification of height systems. Improved knowledge in each of these fields will also ensure the accumulation of new understanding of past and present sea-level changes. 相似文献
15.
《Astronomy& Geophysics》2008,49(1):1.09-1.12
Ian Crawford, Mahesh Anand, Andrew Ball and Katherine Joy report on a UK community meeting on lunar exploration, held at the Open University on 24 and 25 September 2007. 相似文献
16.
A field reconnaissance mission was led to the areas affected by the disaster caused by the Magnitude 7.9 earthquake event
of 15/08/2007 near the city of Pisco in Peru. The main objectives of the mission were to collect data and make observations
leading to improvements in design methods and techniques for strengthening and retrofit, and to assist the phase of reconstruction.
The mission focused on the behaviour of non-engineered structures, in particular those of adobe constructions. The findings
of the mission confirmed that most of the damage was observed on adobe houses constructed with traditional non anti-seismic
techniques which either collapsed or nearly collapsed, causing 519 deaths, 1,366 injuries and more than 58,000 houses destroyed.
The mission also confirmed that buildings constructed according to modern earthquake resistant design standards performed
with no evident damage. All the parties contacted during the mission, especially the EC Delegation, showed particular interest
in the results of the present mission report, which will be taken into consideration when planning the reconstruction phase,
especially of the most distant rural areas, where close collaboration between the Governmental Institutions, International
Organizations, Universities and NGO’s, will be needed to assist the population for the adoption of earthquake resistant designs
in the reconstruction of the destroyed houses. 相似文献
17.
Penhill Farm is an Earlier Stone Age (ESA) Acheulean archaeological site located within the southeastern Cape coastal region of South Africa. Although ESA artifacts have been known for this region since the 1950s, limited archaeological work and an inability to date the terrace context sites have prevented understanding the technological progression from the ESA to Middle Stone Age (MSA) and their placement within the Stone Age chronology of South Africa. Here we use cosmogenic 26Al and 10Be to reveal a two-stage depositional history for a stone tool assemblage recovered from a debris flow deposit, with artifacts dating to ca. 1.1 Ma (million years) incorporated into a debris flow dating to ca. 0.6 Ma, thereby constraining the Penhill Farm Acheulean occupation to the Early Pleistocene. 相似文献
18.
A Wavelet-Based Assessment of Topographic-Isostatic Reductions for GOCE Gravity Gradients 总被引：3，自引：2，他引：1
Gravity gradient measurements from ESA’s satellite mission Gravity field and steady-state Ocean Circulation Explorer (GOCE) contain significant high- and mid-frequency signal components, which are primarily caused by the attraction of the Earth’s topographic and isostatic masses. In order to mitigate the resulting numerical instability of a harmonic downward continuation, the observed gradients can be smoothed with respect to topographic-isostatic effects using a remove–compute–restore technique. For this reason, topographic-isostatic reductions are calculated by forward modeling that employs the advanced Rock–Water–Ice methodology. The basis of this approach is a three-layer decomposition of the topography with variable density values and a modified Airy–Heiskanen isostatic concept incorporating a depth model of the Mohorovi?i? discontinuity. Moreover, tesseroid bodies are utilized for mass discretization and arranged on an ellipsoidal reference surface. To evaluate the degree of smoothing via topographic-isostatic reduction of GOCE gravity gradients, a wavelet-based assessment is presented in this paper and compared with statistical inferences in the space domain. Using the Morlet wavelet, continuous wavelet transforms are applied to measured GOCE gravity gradients before and after reducing topographic-isostatic signals. By analyzing a representative data set in the Himalayan region, an employment of the reductions leads to significantly smoothed gradients. In addition, smoothing effects that are invisible in the space domain can be detected in wavelet scalograms, making a wavelet-based spectral analysis a powerful tool. 相似文献
19.
Martin Füllekrug Declan Diver Jean-Louis Pinçon Alan D. R. Phelps Anne Bourdon Christiane Helling Elisabeth Blanc Farideh Honary R. Giles Harrison Jean-André Sauvaud Jean-Baptiste Renard Mark Lester Michael Rycroft Mike Kosch Richard B. Horne Serge Soula Stéphane Gaffet 《Surveys in Geophysics》2013,34(1):1-41
The French government has committed to launch the satellite TARANIS to study transient coupling processes between the Earth’s atmosphere and near-Earth space. The prime objective of TARANIS is to detect energetic charged particles and hard radiation emanating from thunderclouds. The British Nobel prize winner C.T.R. Wilson predicted lightning discharges from the top of thunderclouds into space almost a century ago. However, new experiments have only recently confirmed energetic discharge processes which transfer energy from the top of thunderclouds into the upper atmosphere and near-Earth space; they are now denoted as transient luminous events, terrestrial gamma-ray flashes and relativistic electron beams. This meeting report builds on the current state of scientific knowledge on the physics of plasmas in the laboratory and naturally occurring plasmas in the Earth’s atmosphere to propose areas of future research. The report specifically reflects presentations delivered by the members of a novel Franco-British collaboration during a meeting at the French Embassy in London held in November 2011. The scientific subjects of the report tackle ionization processes leading to electrical discharge processes, observations of transient luminous events, electromagnetic emissions, energetic charged particles and their impact on the Earth’s atmosphere. The importance of future research in this area for science and society, and towards spacecraft protection, is emphasized. 相似文献
20.
《Journal of Atmospheric and Solar》2000,62(14):1251-1255
We report here preliminary results of a mission analysis for a space weather monitoring system that provides continuous transmission of solar wind conditions 0.10 A.U. upstream from Earth. The system is based on four platforms that are phased into eccentric heliocentric orbits but, from the perspective of a fixed Sun–Earth line, the spacecraft appear to orbit Earth. This system offers a 10× improvement in reporting solar wind plasma and magnetic field characteristics beyond similar platforms located at the Lagrangian L-1 point. We describe launch and energy considerations, along with a preliminary analysis of communication requirements. The Space Weather Diamond offers significant potential for scientific insight into problems requiring coordinated observations from multiple vantage points by providing the ability to separate spatial from temporal variations. We discuss examples for payloads including both in situ and remote sensing instrumentation. 相似文献