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Moessbauer spectroscopy is a powerful tool for the mineralogical analysis of Fe-bearing materials. The miniaturized Moessbauer spectrometer MIMOS II has already been working on the surface of Mars for 6 years as part of the NASA Mars Exploration Rovers mission. The improved version of the instrument is a component of the scientific payload of the Phobos-Grunt mission. The scientific objectives of the instrument are the following: to identify the iron-bearing phases, to determine the quantitative distribution of iron among these phases, and to determine the distribution of iron among its oxidation states.

The exploration of planet moons and minor bodies (Avduevskii et al., 1996) is a basic task for comprehending the nature of the processes occurring in our Solar System. Knowing the current state of the moons, we can better describe their past and look into the future. This knowledge is important, first of all, for understanding the origin of the Solar System. Interest in the Martian moon Phobos has been displayed during recent decades. The interest is caused by some questions to which there have been no answers up until now (Sagdeev et al., 1988; 1989). For example, there is a question regarding the origin of the moon: whether it is an asteroid captured by Mars’ gravitational field or it is an accumulated body in the Martian orbit. In connection with this, it is interesting to conduct studies aimed at answering this question. If Phobos appears to be an asteroid, then investigations regarding the chemical and isotopic compositions of the moon as the primary matter of the Solar System as well as its evolution are of great interest.

We consider a new design of a high-precision three-axial sensor of angular velocities whose sensitive elements are fiber optic gyroscopes using the Sagnac effect. The instrument is designed for measuring the rotation velocity of an orbiting spacecraft (microsatellite) and for performing its attitude control.

The goal of this paper is to summarize the experimental data on the atmosphere of Venus obtained after 1985, when the VIRA (Venus International Reference Atmosphere) or COSPAR model was published. Among the most important results that have appeared since then are the following: measurements of the vertical temperature profile by the VEGA spacecraft with high precision and high altitude resolution; measurements made with balloons of the VEGA spacecraft; radio occultation measurements of Magellan, Venera-15, and Venera-16; and temperature profiles derived from the data of infrared spectrometry obtained by Venera-15. The new result as compared to VIRA is the creation of a model of the atmosphere in the altitude range 55 to 100 km dependent on local time. This model is presented in our paper in tabulated form.

A quartz sensor of small accelerations with a capacitive transducer is designed and produced, allowing one to measure spacecraft accelerations with a resolution of 10–7 m/s2 in the range ±10–1 m/s2. The results of calibration of the sensor by the method of inclinations are presented.

A gas-discharge anemometer is designed for investigating the gas-flow dynamics in wind tunnels, and in experimental and space meteorology. The anemometer allows one to measure simultaneously the magnitude and direction of the gas-flow velocity vector and the gas pressure in the flow. The instrument consists of a gas-discharge chamber, an analyzer of scattered ions, a power supply unit, and a measuring unit. The anemometer weight does not exceed 0.1 kg, and the power consumption does not exceed 0.2 W. The instrument was put through preliminary tests in a wind tunnel that simulated, in particular, the conditions in the boundary layer of the Martian atmosphere and produced a directed gas (air or CO2) flow whose velocity could be varied from 0.5 to 50 m/s at pressures from 0.3 to 1.3 kPa and temperatures from –120 to +20°C. The anemometer sensitivity is no worse than 100 mV/(m/s). The method of calculating the gas-flow velocity on the basis of the measured ion-current distributions is developed.

For experimental testing of a Mars balloon probe in the upper layers of the Earth's atmosphere a specified parachute system was developed, fabricated and tested in 3 high-altitude balloon flights. The balloon volumes were 130000 and 180000 m 3 with the payloads of 500 – 900 kg; the maximum flight altitude reached 32 km. The experiments showed that one-canopy parachute system with the area of 1200 m 2 has certain advantages as compared to the four-canopy system and can be used both in Mars balloon tests in the Earth's stratosphere and as a parachute system of the descent apparatus for investigation of Mars.

On June 11 and 15, 1985 two packages with balloons have been inserted in the atmosphere of Venus from the Soviet VEGA landing modules. This paper summarizes the pressure, temperature, wind illumination and backscattering data from the balloons.

The spectra of Venus thermal radiation obtained in the Fourier-spectrometer experiment on board Venera-15 orbiter are analysed in the spectral ranges covering the √2 (520 cm−1) and √3 (1350 cm−1) SO2 bands and the features of the H2O pure rotation band (250–450 cm−1). The abundances and vertical distributions of these gases in the altitude range 60–65 km are determined. Different types of variations of gas amounts in the atmosphere are discussed.

A relatively simple eye-safe compact lidar with full solid state elements for measuring the aerosol backscatter coefficient and cloud height has been developed and tested. The lidar produces detailed the backscatter coefficient profiles within a hundred meters in daytime with a signal-to-noise ratio of 1:20. An important feature of this instrument is its ability to measure backscatter and extinction coefficient, cloud and invisible atmospheric layers height with its reflectivity, and background quantum flow, simultaneously. By using the direct relationship between backscattering, extinction, and liquid water content these measurements can be converted to the meteovisibility and aerosol mass loading in fog and clouds. >

Measurements of angular velocities in the cloud layer of the Venusian atmosphere from photographs in the ultra-violet range [1, 2], from the Doppler shift in spectroscopic data [3] and, then, from radio measurements of signals of the USSR [4] and USA descending vehicles, entering the atmosphere, have shown that the atmosphere of Venus, as a whole, rotates in the same direction, as the planet itself (the retrograde rotation), but more than ten times faster. The planet’s period of rotation is about 240 terrestrial days, and the period of rotation of the atmosphere’s upper layers equals four days, approximately. Measurements performed by descending vehicles have shown that the angular velocity of wind has, basically, zonal retrograde direction at all altitudes and at various latitudes. This fact was also confirmed during the flight of two aerostat probes with duration of two terrestrial days for each. It turns out that the following amusing fact takes place: the whole atmosphere rotates faster than the planetary surface, and it should transfer the angular momentum to the planet due to friction. This implies that a constant external moment of forces should act upon the atmosphere for maintaining its fast rotation. Several models of origination of the external momentum were suggested [5], but none of them provides necessary velocities of the cloud layer. A model of formation of the external moment of forces acting upon the cloud layer is considered in this paper. The model explains superrotation and the appearance of retrograde rotation of the atmosphere. During the planet lifetime the retrograde momentum has transferred from the atmosphere to the solid surface and could result in retrograde rotation of the planet itself. The model is based on the experimentally confirmed

A relatively simple eye-safe compact solid-state lidar for measuring the aerosol backscatter coefficient and cloud height has been developed and tested. The performance of the laser radar based on the semiconductor laser and Single Photon Avalanche Diode as a receiver are discussed. The lidar produces detailed the backscatter coefficient profiles within a hundred meters in daytime with a signal-to-noise ratio of 1:20. By using the direct relationship between backscattering, extinction, and liquid water content these measurements can be converted to the meteovisibility and aerosol mass loading in fog and clouds. Indoor and outdoor data are presented.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Infrared spectra of Venus measured by means of the Fourier spectrometer aboard Venera 15 orbiter were used for retrievals of temperature profiles of the atmosphere in the altitude range from 60 to 95 km. Monotonous profiles are typical for latitudes lower than 60° latitude, but on the dayside near the equator some traces of the upper atmospheric inversion were found in the profiles. At latitudes greater than 60°N the profiles contain an isothermal or inversional part between 10 and 100 hPa pressure levels. Temperature profiles inside the “warm dipole” maxima are the same as outside of this region and consequently these optical properties should be explained only by peculiarities of cloud structure there.

A planned experiment to obtain range and Doppler data with the Phobos 2 Lander on the surface of the Martian satellite Phobos is described. With the successful insertion on January 29, 1989 of Phobos 2 into Mars orbit, it is anticipated that the Lander will be placed on the surface of Phobos in April 1989. Depending on the longevity of the Lander, range and Doppler data for a period of from one to several years are expected. Because these data are of value in performing solar-system tests of general relativity, the current accuracy of the relevant relativity tests using Deep Space Network data from the Mariner-9 orbiter of Mars in 1971 and from the Viking Landers in 1976-1982 is reviewed. The expected improvement from data anticipated during the Phobos 2 Lander Mission is also discussed; most important will be an improved sensitivity to any time variation in the gravitational 'constant' as measured in atomic units.

Fourier spectrometers for the investigation of infrared spectra of Venus were installed on the recent Soviet orbiters “Venera-15” and “Venera-16”. Many spectra with reliable absolute calibration were obtained in the 280–1500 cm −1 region with a spectral resolution of 5 cm −1 (ground based processing) and about 7 cm −1 (preoprocessed on board) and a spatial resolution of about 100 km at the Venusian cloud top level. Bands of CO 2 , H 2 O, H 2 SO 4 and SO 2 are identified. The 15 μm-CO 2 - fundamental band was used for retrieval of altitude dependent temperature profiles. There are significant differences in the cloud structure above 60 km for distinct regions of Venus, demonstrated by differences in the spectra.

The VEGA balloons made in situ measurements of pressure, temperature, vertical wind velocity, ambient light, frequency of lightning, and cloud particle backscatter. Both balloons encountered highly variable atmospheric conditions, with periods of intense vertical winds occurring sporadically throughout their flights. Downward winds as large as 3.5 meters per second occasionally forced the balloons to descend as much as 2.5 kilometers below their equilibrium float altitudes. Large variations, in pressure, temperature, ambient light level, and cloud particle backscatter (VEGA-1 only) correlated well during these excursions, indicating that these properties were strong functions of altitude in those parts of the middle cloud layer sampled by the balloons.

Thermal structure measurements obtained by the two VEGA balloons show the Venus middle cloud layer to be generally adiabatic. Temperatures measured by the two balloons at locations roughly symmetric about the equator differed by about 6.5 kelvins at a given pressure. The VEGA-2 temperatures were about 2.5 kelvins cooler and those of VEGA-1 about 4 kelvins warmer than temperatures measured by the Pioneer Venus Large Probe at these levels. Data taken by the VEGA-2 lander as it passed through the middle cloud agreed with those of the VEGA-2 balloon. Study of individual frames of the balloon data suggests the presence of multiple discrete air masses that are internally adiabatic but lie on slightly different adiabats. These adiabats, for a given balloon, can differ in temperature by as much as 1 kelvin at a given pressure.

A global array of 20 radio observatories was used to measure the three-dimensional position and velocity of the two meteorological balloons that were injected into the equatorial region of the Venus atmosphere near Venus midnight by the VEGA spacecraft on 11 and 15 June 1985. Initial analysis of only radial velocities indicates that each balloon was blown westward about 11,500 kilometers (8,000 kilometers on the night side) by zonal winds with a mean speed of about 70 meters per second. Excursions of the data from a model of constant zonal velocity were generally less than 3 meters per second; however, a much larger variation was evident near the end of the flight of the second balloon. Consistent systematic trends in the residuals for both balloons indicate the possibility of a solar-fixed atmospheric feature. Rapid variations in balloon velocity were often detected within a single transmission (330 seconds); however, they may represent not only atmospheric motions but also self-induced aerodynamic motions of the balloon.

Both VEGA balloons encountered vertical winds with typical velocities of 1 to 2 meters per second. These values are consistent with those estimated from mixing length theory of thermal convection. However, small-scale temperature fluctuations for each balloon were sometimes larger than predicted. The approximate 6.5-kelvin difference in temperature consistently seen between VEGA-1 and VEGA-2 is probably due to synoptic or planetary-scale nonaxisymmetric disturbances that propagate westward with respect to the planet. There is also evidence from Doppler data for the existence of solar-fixed nonaxisymmetric motions that may be thermal tides. Surface topography may influence atmospheric motions experienced by the VEGA-2 balloon.

International audience; The VEGA Venus balloon radio transmissions received on Earth were used to measure the motion of the balloons and to obtain the data recorded by onboard sensors measuring atmospheric characteristics. Thus the balloons themselves, the gondolas, the onboard sensors, and the radio transmission system were all components of the experiment. A description of these elements is given, and a few details of data sampling and formatting are discussed.

A global array of 20 radio observatories was used to measure the three-dimensional position and velocity of the two meteorological balloons that were injected into the equatorial region of the Venus atmosphere by the VEGA spacecraft.

In June 1985, two instrumented balloons were placed in the atmosphere of Venus as part of the VEGA mission. Each balloon traveled about 30 percent of the way around the planet at a float altitude near 54 kilometers. In situ sensors measured pressure, temperature, vertical wind velocity, cloud particle backscatter, ambient light level, and frequency of lightning. A ground-based network of 20 radio antennas tracked the balloons by very long baseline interferometry (VLBI) techniques to monitor the Venus winds. The history, organization, and principal characteristics of this international balloon experiment are described.

Fourier spectrometers aboard the Venera 15 and 16 orbiters measured the outgoing spectral radiance of Venus in the 250–1600-cm−1 (Venera 15) and 400–1600-cm−1 (Venera 16) regions with a spectral resolution of 5–7 cm−1 depending on the data handling procedure. This paper gives a short description of the experimental design and discusses those aspects that can be suitably tackled by wide range spectral measurements. Different Venusian regions can be characterized by typical and significantly different radiance and brightness temperature spectra based on the magnitude of brightness temperatures and also on secondary spectral signatures caused by H2SO4 bands as well as isotopic and hot CO2 bands. At least five groups can be identified, one typical for equatorial regions, one for mid-latitudes, and three for the subpolar and polar regions. Estimates of H2O and SO2 abundances were obtained (∼30 ppm at 58 km and ∼2 ppm at 65 km, respectively). SO2 is first identified in the infrared by our measurements. A detailed comparison between computed and measured spectra for the transition zone between mid-latitudes and the cold subpolar region gives arguments that the cloud top is situated within the temperature inversion and not above or below it.