ALBERT

Description: A refinement was obtained in the earth's gravitational field using satellite and surface data. In addition to a more complete treatment of data previously employed on 27 satellites, the new satellite solution (Goddard Earth Model 7) includes 64,000 laser measurements taken on 7 satellites during the international satellite geodesy experiment (ISAGEX) program. The GEM 7, containing 400 harmonic terms, is complete through degree and order 16. The companion solution GEM 8 combines the same satellite data as in GEM 7 with surface gravimetry over 39% of the earth. The GEM 8 is complete to degree and order 25. Extensive tests on data independent of the solution show that the undulation of the geoidal surface computed by GEM 7 has an accuracy of about 3m (rms). The overall accuracy of the geoid estimated by GEM 8 is estimated to be about 4-1/4m (rms), an improvement of almost 1m over previous solutions.

Description: Evaluation of numerous data from different methods of measurement and theories applied in high-pressure physics shows that the strain energy of a monophase system, which represents the low- or a high-pressure phase of a hydrostatically compressed substance mostly relevant to planetary physics, approximates to a term proportional to the square of an auxiliary function of the volumetric contraction, the bulk modulus and its successive partial derivatives with respect to pressure at the initial state of the thermodynamical system. From this it follows that new-defined polynomial equations in the initial values of the bulk modulus and its pressure derivatives must be satisfied, which is checked for many elements, halides, oxides, minerals, and rocks. Using a suitably chosen auxiliary function, the strain energy, pressure, bulk modulus and its first pressure derivative at any equilibrium state of the monophase system are represented by approximation functions of the volumetric contraction as well as the initial values of the bulk modulus and its derivatives. The information content of these functional relations called Model N if they include derivatives of the bulk modulus only up to the order N surpasses, already in the cases N = 1 end N = 2, that of other relations hitherto used for interpreting the compressional behaviour of different substances. Model 1 is discussed on the base of more than 70 substances with various compressional properties, among them stishovite and solid hydrogene, proved to be suitable, in particular, for the physics of the interiors of the Earth and of terrestrial planets. Considering the reliability of the data material available, Model 1 is pointed out to predict experimental values from the tested substances for volumetric contractions down to about 0.5 with a relative error between 1 % and 5 %. Model 2, extending the information volume of Model 1, turns out to be appropriate for volumetric contractions less than 0.5 as is the case in the interiors of the Jovian planets. For practical use of both models tables and graphs of sensitivities and errors of significant quantities are presented. In case data from shock-wave experiments on rocks and minerals are available, Model 1 is used for identification of crystal structures of high-pressure phases. As a result, for the majority of high-pressure phases the compressional behaviour differs from that of the corresponding oxide mixtures. For some substances new conclusions on their crystal structures can be drawn.

Description: 1. Introduction 2. Basic relations 3. Approximations for the equation of state 4. The conditions of the auxiliary variable 5. Development of Model 1 and Model 2 6. Practical analysis of the models 6. 1. Preliminaries 6.2. The parameters "0 and "1 6.3. Intercomparison of different forms of the equation of state 6.4. The parameter n2 6.5. Problems of accuracy 6.6. Discussion of [x,P]-data of elements 6.7. Discussion of [x,P]-data of halides 6.8. Discussion of [x,P]-data of oxides, minerals, and rocks 6.9. On the "interpolating equations of state" 7. Conclusion 8. Tables and Figures References

Description: Zur Wahrung der Einheitlichkeit und Richtigkeit geodätischer Längenbestimmungen wurde ein neues Interferometer entwickelt. Bei ersten Messungen auf der .Nordhälfte der Standardbasis Potsdam hat es sich bewährt. Untersuchungen und Messungen gaben Aufschluß über die Eigenschaften des Maßsystems. Das Gerät ist ein modifiziertes VÄISÄLÄ-Interferometer. Es verbindet die Vorteile des in der Praxis bewährten optischen Grundprinzips der Erzeugung von Interferenzen durch FRAUNHOFERsche Beugung am Doppelspalt mit einigen Neuerungen. Zu diesen gehören ein Verfahren des Streckenaufbaus, bei dem alle Spiegel während des Meßvorganges stehen bleiben können, die Verwendung eines .Ausgangsnormals mit planparallelen Endflächen und die Streckenübertragung zu den geodätischen Festlegungen mit Hilfe von Lotstäben.