High temperature, wireless seismometer sensor for Venus
Space agency mission plans state the need to measure the seismic activity on Venus. Because of the high temperature on Venus (462°C average surface temperature) and the difficulty in placing and wiring multiple sensors using robots, a high temperature, wireless sensor using a wide bandgap semiconductor is an attractive option. This paper presents the description and proof of concept measurements of a high temperature, wireless seismometer sensor for Venus. A variation in inductance of a coil caused by the movement of an aluminum probe held in the coil and attached to a balanced leaf-spring seismometer causes a variation of 700 Hz in the transmitted signal from the oscillator/sensor system at 426°C. This result indicates that the concept may be used on Venus.
The geophysical research program for Venus landing station
Classes of Scientific research tasks. 1.Tectonic activity and solar tides.2 Venus seismic activity.3. Internal structure. 4 Volcanic activity. 5 Structure of a micro seismic field and seismic noise. 6 Dynamic, acoustic and electromagnetic processes in an atmosphere. 7 Mechanical and acoustic characteristics of a ground, electric conductivity. 8 Thermal deep stream. Methods and Instruments apply for decisions of tasks (1-8). 1. Registration of seism acoustic waves, micro seismic fields etc. The equipment: 3-th axial componential seismometer established on Venus surface and which can function on temperature condition ~500 C o . Common weight (mechanical system + electronics block inside station) 0,8 kg; Consume power 50 mW; Dimensions-10x10x10 sm; Mode of functioning – event recorded, i.e. on excess of a signal on an input in system. The 1-axial high-frequency seismometer established either inside station, or outside of; dump in shockproof variant in separate micropenetrator is possible: Common weight a seismometer + electronics 0,250 kg; together with micropenetrator, a radioisotope power source and local telemetry 3,0 3,5 kg; overloads 3.000 g.Consume power ~ 10 mW. 2. Registration of dynamic processes in an atmosphere. Two specialized devices of micro phonic type external and internal accommodation: General weight 0,1 kg; Consume power 5 mW. 3. Recording of electromagnetic processes in an atmosphere. The mode of reception onboard is possible. 4. Research of properties of a ground. Installation of several send-receive electric and ultrasonic sources in a ground part of a landing ring in weight 0,05 kg. 5. Thermal heat deep streamonly with micropenetrator using. Expedition expected research results. Full performance of seismic experiments will allow receiving the following preliminary results: The conclusion about a level of tectonic activity of Venus: seismisity, volcanic activity, it is possible about seism tectonic currents. Preliminary qualitatively authentic model of an internal structure of Venus: a corn, a mantle, a crust. To start of Venus atmosphere dust research. To start determine of a property soil parameters. To determine the thermal flow from deep structure and geochemical composition of a crust and the top Venus mantle. To determine and update some solar system parameters and planets origin models. Testing priority advanced methods and technologies for research of Solar system bodies. Transmission space technologies for needs a scientific and technical industry complex.
A Thermochemical Study of Equilibrium Relations during Metamorphism of Siliceous Carbonate Rocks
The stability relations of a number of mineral assemblages formed by metamorphism of siliceous dolomites, magnesites, and calcites are defined by the use of thermochemical data. The calculated equilibrium curves are in excellent agreement with available experimental determinations. Possible deviations of reaction temperatures in nature from the theoretical curves are discussed, and the theoretical curves are shown always to give maximum P, T-values for any given reaction. The sequence of reactions occurring during progressive "equilibrium" metamorphism of siliceous carbonates differs from the Bowen (1940)-Tilley (1951a) reaction series in that diopside becomes stable before forsterite and wollastonite before periclase. The calculated sequence is in excellent agreement with field observations in areas of regional metamorphism. The Bowen-Tilley series appears to be a result of the metastable persistence of mineral assemblages above their equilibrium reaction curves. The P, T time-conditions in the various metamorphic facies are discussed, and a "petrogenetic grid" is constructed to establish limits on the CO₂ pressures necessary if the assemblage calcite-quartz is to remain stable in the amphibolite and granulite facies. Some calculations on the thermal history of contact aureoles around small basaltic intrusions are presented in an appendix.