Astrodynamical Space Test of Relativity using Optical Devices I (ASTROD I)—a class-M fundamental physics mission proposal for cosmic vision 2015–2025: 2010 Update

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 3 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 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.For this mission, accurate pulse timing with an ultra-stable clock, and a drag-free spacecraft with reliable inertial sensor are required. T2L2 has demonstrated the required accurate pulse timing; rubidium clock on board Galileo has mostly demonstrated the required clock stability; the accelerometer on board GOCE has paved the way for achieving the reliable inertial sensor; the demonstration of LISA Pathfinder will provide an excellent platform for the implementation of the ASTROD I drag-free spacecraft. These European activities comprise the pillars for building up the mission and make the technologies needed ready. A second mission, ASTROD or ASTROD-GW (depending on the results of ASTROD I), is envisaged as a three-spacecraft mission which, in the case of ASTROD, would test General Relativity to one part per billion, enable detection of solar g-modes, measure the solar Lense-Thirring effect to 10 parts per million, and probe gravitational waves at frequencies below the LISA bandwidth, or in the case of ASTROD-GW, would be dedicated to probe gravitational waves at frequencies below the LISA bandwidth to 100?nHz and to detect solar g-mode oscillations. In the third phase (Super-ASTROD), larger orbits could be implemented to map the outer solar system and to probe primordial gravitational-waves at frequencies below the ASTROD bandwidth. This paper on ASTROD I is based on our 2010 proposal submitted for the ESA call for class-M mission proposals, and is a sequel and an update to our previous paper (Appouchaux et al., Exp Astron 23:491?C527, 2009; designated as Paper I) which was based on our last proposal submitted for the 2007 ESA call. In this paper, we present our orbit selection with one Venus swing-by together with orbit simulation. In Paper I, our orbit choice is with two Venus swing-bys. The present choice takes shorter time (about 250?days) to reach the opposite side of the Sun. We also present a preliminary design of the optical bench, and elaborate on the solar physics goals with the radiation monitor payload. We discuss telescope size, trade-offs of drag-free sensitivities, thermal issues and present an outlook.     

Relativistic astrometry

Concepts of relativistic astrometry — such as Weyl's stellar compass or the concept of flat-space plus forces — are discussed. To visualize effects from light deflection pictures showing the stellar sky as seen from the vicinity of a strongly gravitating source are presented.Communication presented at the International Conference on Astrometric Binaries, held on 13–15 June, 1984, at the Remeis-Sternwarte Bamberg, Germany, to commemorate the 200th anniversary of the birth of Friedrich Wilhelm Bessel (1784–1846).     

Über Schwankungen von Mächtigkeit und Dichte ostalpiner Firnfelder

Zusammenfassung Mächtigkeit und Dichte ostalpiner Firnschneefelder schwanken im Jahresablauf innerhalb weiter Grenzen. In den Jahresfirnschichten herrschen aus glazialklimatischen Gründen im Winter die geringsten und am Ende des Spätsommers die größten Dichten. Ungewöhnliche Witterungseinflüsse bewirkten, daß im Februar 1949 komprimiertere Schneedecken als im Herbst 1948 lagen. Die einzelnen Jahresfirnrücklagen 1948 bis 1950 ergaben Ende August/Anfang September mittlere Dichten von 0,51, 0,68 und 0,68. Unterhalb der Firndecke 1949/50 verdichteten sich die Firnüberschüsse von 1948/49 und 1947/48 im Durchschnitt auf 0,78 bzw. 0,79. Als Auswirkung verschieden häufiger und intensiver Durchfeuchtung wurde im Sommer und Herbst in der Nivalregion eine deutliche Abnahme der Dichte mit wachsender Meereshöhe erkannt. Südgerichtete Firnfelder deuteten mit maximaler Dichte unterschiedlichen Strahlungseinfluß auf verschiedene Expositionen an. In winterlichen Monaten verdichteten sich Firndecken in windgeschützteren Lagen weniger stark als sehr windexponierte Firnflächen. Im Vertikalaufbau der Jahresfirnlagen ließ sich im Winter eine recht unregelmäßige Dichtezunahme mit der Tiefe und in ihren tiefsten Schichten eine deutliche Abnahme beobachten.

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Summary Thickness and density of glacial snow-fields in the Eastern Alps vary, in the course of a year, within wide limits. It is due to glacial climate that the yearly snow-layers show a minimum of density in winter and a maximum in the latter part of summer. However, caused by extraordinary weather conditions, the snow-covers were more compressed in February 1949 than in autumn 1948. The yearly residues of snow from 1948 to 1950 showed, at the end of August and the beginning of September, average densities of 0,51, 0,68 and 0,68 respectively. Below the snow-cover of 1949/50 the surplus quantities of snow from 1948/49 and 1947/48 were condensed on the average to 0,78 and 0,79 respectively. As the snow-region was soaked more or less frequently and intensively, an obvious decrease of density with altitude was found in summer and autumn. The maximum densities of snow-fields exposed in southern directions indicate the various effects of radiation in different expositions. During the winter months, snow-covers situated so as to be more or less protected from wind were condensed less than those open to windeffect. The vertical structure of the yearly layers shows a rather irregular increase of density with depth in winter, whereas in the deepest layers a distinct increase could be observed.

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Résumé Dans les Alpes orientales l'épaisseur et la densité des névés glaciaires varient entre de larges limites; pour des raisons de climatologie glaciaire, les couches annuelles présentent leur densité minimum en hiver et maximum à la fin de l'été. Des conditions de temps exceptionnelles ont eu pour effet qu'en février 1949 il y avait des couches de neige plus comprimées qu'en automne 1948. Les restes neigeux annuels des névés glaciaires 1948–1950 ont fourni à la fin d'août ou au commencement de septembre des densités moyennes de 0,51, 0,68 et 0,68. Au-dessous de la couche du névé 1949/50 les excédents restants de 1948/49 et 1947/48 ont accru leur densité jusqu'à 0,78 et 0,79 respectivement. On a observé en été et en automne dans la région nivale, une nette diminution de la densité avec l'altitude, conséquence d'une humidification plus ou moins fréquente et intense. Les champs de névé exposés au Sud indiquent par leur densité maximum des effects variables du rayonnement dans des expositions différentes. Pendant les mois d'hiver les couches de névé des endroits situés à l'abri du vent voient leur densité augmenter moins fortement que celles des endroits très exposés au vent. En ce qui concerne la structure verticale des couches de névé annuelles, on constate en hiver un accroissement, très, irrégulier de la densité avec la profondeur, et dans les couches les plus profondes une nette diminution.

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Mit 1 Textabbildung.     

Glacier response in the European Alps to Heinrich Event 1 cooling: the Gschnitz stadial

The Gschnitz stadial was a period of regionally extensive glacier advance in the European Alps that lies temporally between the breakdown of the Last Glacial Maximum piedmont lobes and the beginning of the Bølling warm interval. Moraines of the Gschnitz stadial are found in medium to small catchments, are steep‐walled and blocky, and reflect a snowline lowering of 650–700 m in comparison to the Little Ice Age reference snowline. ¹⁰Be surface exposure dating of boulders from the moraine at the type locality at Trins (Gschnitz valley, Tyrol, Austria) shows that it stabilised no later than 15 400 ± 1400 yr ago. The overall morphological situation and the long reaction time of the glacier suggest that the climatic downturn lasted about 500 ± 300 yr, indicating that the Gschnitz cold period began approximately 15 900 ± 1400 yr ago, if not somewhat earlier. This is consistent with published radiocarbon dates that imply that the stadial occurred sometime between 15 400 ¹⁴C yr BP (18 020–19 100 cal. yr) and 13 250 ¹⁴C yr BP (15 360–16 015 cal. yr). A palaeoclimatic interpretation of the Gschnitz glacier based on a simple glacier flow model and statistical glacier‐climate models shows that precipitation was about one‐third of modern‐day precipitation and summer temperatures were about 10 K lower than today. In comparison, during the Younger Dryas, precipitation in this area was only about 10% less and T_s (summer temperature) was only 3.5–4 K lower than modern values. Based on the age of the moraine and the cold and dry climate at that time, we suggest that the Gschnitz stadial was the response of Alpine glaciers to cooling of the North Atlantic Ocean associated with Heinrich Event 1. Copyright © 2005 John Wiley & Sons, Ltd.     

Backstripping dip-slip fault histories: apparent slip rates for the Miocene of the Vienna Basin

Backstripped basement subsidence histories from both the hanging wall and the footwall blocks adjacent to synsedimentary normal faults can be used to reconstruct the sense of fault motion through time and to quantify the vertical component of fault slip. Consequently, apparent dip-slip rates of faults can be calculated for each stratigraphic interval and times of increased fault activity can be distinguished. An application of this method to well data along a transect through the central part of the Miocene Vienna Basin indicates that two distinct phases of faulting occurred during the Karpatian, with rates as high as 3000 m Myr⁻¹. Changes in the sense of movements during the early Karpatian and the earliest Badenian indicate a major rearrangement in the fault patterns. During the early Sarmatian another short pulse of dip-slip is recorded along the investigated faults.     

Ecotopic and ontogenetic trophic variation in mojarras (Pisces: Gerreidae)

Seven species of mojarras (Gerreidae) were collected from three stations in the Indian River lagoon near the Sebastian Inlet, Florida over an eighteen month period to study spatial and temporal variations in occurrence and feeding habits. Two major habitats common to this area were represented in the study; a sandy beach and a seagrass flat. Of the 2,899 gerreids collected,Eucinostomus gula represented 67% and was found primarily in theHalodule seagrass site. The next most abundant species,E. argenteus (11%),E. jonesi andE. lefroyi (each 10%), were found most frequently at the inlet site.Diapterus auratus, E. melanopterus, andGerres cinereus were captured infrequently and were considered incidental. Prey items found included amphipods, bivalves, copepods, fish eggs, foraminifera, isopods, nematodes, ostracods, polychaetes and crustacean parts. Significant amounts of sand and unidentifiable amorphous debris were also included in the gut content analysis. Little interspecific variation in diet was found among the four major species examined. The general shift seen from a diet composed primarily of copepods and other crustaceans to one of polychaetes suggests an intraspecific ontogenetic progression. Spatial variations in diet composition were also indicated between the two major habitats. Feeding analyses showed gerreids to be diurnal feeders with the greatest consumption (total gut content weight) occurring at dusk.