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1.
Methods for calculating the aerodynamic impact of the Martian atmosphere on the descent module “Exomars-2018” intended for solving the problem of heat protection of the descent module during aerodynamic deceleration are presented. The results of the investigation are also given. The flow field and radiative and convective heat exchange are calculated along the trajectory of the descent module until parachute system activation.  相似文献   

2.
V.G. Istomin  K.V. Grechnev 《Icarus》1976,28(2):155-158
In the descent of the automatic interplanetary station Mars 6, after parachute deployment, an analysis was carried out by means of a mass spectrometer, the analyzer of which was pumped out by a getter-ion pump. Unfortunately, mass spectra were not obtained. But during vehicle descent on a parachute tether, the pump discharge current was registered. The dynamics of the pump current at the end of descent operations imply that an inert gas is a basic component of the Martian atmosphere, along with CO2. Laboratory post-experiment calibrations of other getter-ion pumps, performed with various mixtures of CO2 and argon, result in a probable value of the argon content in the Martian atmosphere of 35 ± 10% by volume.  相似文献   

3.
Ralph D. Lorenz 《Icarus》2006,182(2):559-566
The Huygens probe lost heat to its cold environment during its descent through Titan's atmosphere and after landing. Here I report measurements of the probe's thermal behavior and comparison with ground tests (1) to provide a context for other scientific investigations, such as the release of volatiles from the landing site, and (2) to place constraints on Titan environmental parameters directly, such as the thermal conductivity of the surface material and the strength of winds at the surface. Near-surface winds are constrained to be less than 0.2 m s−1, and probably much less.  相似文献   

4.
A one-dimensional numerical model with a size distribution of aerosol particles in Martian atmosphere is developed. The model incorporates detailed microphysics and turbulent transport. Dust particles suspended in the Martian atmosphere play a role of cloud condensation nuclei. Diurnal cycle of condensational processes is obtained on the basis of GCM temperature profiles. An effective radius of ice particles is 1–2 μm near the lower boundary of cloud layer and 0.2–0.3 μm at the altitude of 50–60 km. These results are consistent with solar infrared occultations by SPICAM experiment on Mars-Express. Near-surface fogs may form under specific conditions. The connections of condensational processes and cloud macroscopic parameters on microphysical properties of aerosol particles are main focus of this paper. In particular, the dependence on variations of cloud condensation nuclei contact parameter is analyzed, taking into account new experimental data of adsorption properties of minerals at low temperatures.  相似文献   

5.
An AOST Fourier spectrometer of the Phobos-Soil project is intended for studying Mars and Phobos by means of measurements of IR radiation spectra of the Martian surface and atmosphere, the Phobos surface, and the spectrum of solar radiation passing through the Martian atmosphere on its limb. The main scientific problems to be solved with the spectrometer on Mars are measurements of methane content, search for minor constituents, and study of diurnal variations in the temperature and atmospheric aerosol. The spectrometer will also study the Martian and Phobos surface both remotely and after landing. The spectral range of the instrument is 2.5?C25 ??m, the best spectral resolution (without apodization) is 0.6 cm?1, and the instantaneous field of view is 2.5°. The recording time of one spectrum is equal to 5 s in solar observations and 50 s in observations of Mars and Phobos. The instrument has self-thermal stabilization and two-axis pointing systems, as well as a built-in radiation source for flight calibration. The spectrometer mass is 4 kg, and power consumption is up to 13 W. Scientific problems, measurement modes, and, briefly, engineering implementation of the experiment are discussed in this work.  相似文献   

6.
Mars-96 mission: Mars exploration with the use of penetrators   总被引：1，自引：0，他引：1  
Within the frames of the Mars-96 Mission the penetrators were first developed for the investigation of the chemical composition and physical properties of the Martian rocks, research into the internal structure of the planet, studying of its surface, atmosphere and climate.The paper briefly describes the penetrator design, the process of its landing and penetration into the Martian surface, items included in the complex scientific instrumentation and their specifications, and principal scientific tasks which can be realized with the use of penetrators.  相似文献   

7.
The paper presents estimates of the occurrence probability of slopes, whose steep surfaces could be dangerous for the landing of the Luna-Glob descent probe (Luna-25) given the baseline of the span between the landing pads (~3.5 m), for five potential landing ellipses. As a rule, digital terrain models built from stereo pairs of high-resolution images (here, the images taken by the Narrow Angle Camera onboard the Lunar Reconnaissance Orbiter (LROC NAC)) are used in such cases. However, the planned landing sites are at high latitudes (67°–74° S), which makes it impossible to build digital terrain models, since the difference in the observation angle of the overlapping images is insufficient at these latitudes. Because of this, to estimate the steepness of slopes, we considered the interrelation between the shaded area percentage in the image and the Sun angle over horizon at the moment of imaging. For five proposed landing ellipses, the LROC NAC images (175 images in total) with a resolution from 0.4 to 1.2 m/pixel were analyzed. From the results of the measurements in each of the ellipses, the dependence of the shaded area percentage on the solar angle were built, which was converted to the occurrence probability of slopes. For this, the data on the Apollo 16 landing region ware used, which is covered by both the LROC NAC images and the digital terrain model with high resolution. As a result, the occurrence probability of slopes with different steepness has been estimated on the baseline of 3.5 m for five landing ellipses according to the steepness categories of <7°, 7°–10°, 10°–15°, 15°–20°, and >20°.  相似文献   

8.
The most detailed information on the seasonal evolution of water vapor distribution in the Martian atmosphere was obtained by the Mars Atmospheric Water Detector (MAWD), which was a five-channel spectrometer operating aboard the Viking 1 and 2 spacecraft in 1977–1980, and from the very recent observations by the Thermal Emission Spectrometer (TES) on the Mars Global Surveyor spacecraft. The TES results show a considerably larger amount of water vapor near the perihelion of Mars (summer in the southern hemisphere) than the estimates based on the MAWD data for this season, which is characterized by the development of global dust storms. The TES and MAWD instruments operated in different spectral regions (20–50 m and 1.38 m, respectively), and this could result in the aforementioned difference because of the effect of aerosol scattering on the intensity of the H2O bands, which becomes significant at short wavelengths. We considered the effect of aerosol scattering on the water vapor content measured in the 1.38-m band, taking into account the different geometries of observations, and restored the H2O content from the MAWD data with allowance for multiple scattering. We obtained a seasonal and spatial distribution of water vapor that showed better agreement with the TES data and, thus, indicated the stability of the hydrological cycle on Mars. Periodic structures, which could possibly be associated with the influence of the stationary planetary waves, are reliably revealed in the zonal distribution of the atmospheric water vapor. The seasonal variability of the wave structures correlates with variations of the latitude gradient of water vapor. This could indicate that wave processes contribute considerably to the meridional water transport in the Martian atmosphere.Translated from Astronomicheskii Vestnik, Vol. 38, No. 6, 2004, pp. 483–496.Original Russian Text Copyright © 2004 by Fedorova, Rodin, Baklanova.  相似文献   

9.
George Ohring 《Icarus》1975,24(3):388-394
The concept is described of deducing the temperature and constituent profile of a planetary atmosphere from orbiter measurements of the planet's ir limb radiance profile. Expressions are derived for the weighting functions associated with the limb radiance profile for a Goody random band model. Analysis of the weighting functions for the Martian atmosphere indicates that a limb radiance profile in the 15 μm CO2 band can be used to determine the Martian atmospheric temperature profile from 20 to 60 km. Simulation of the Martian limb radiance profile in the rotational water vapor band indicates that Martian water vapor mixing ratios can be inferred from limb radiance observations in a water vapor band.  相似文献   

10.
《Planetary and Space Science》2007,55(13):1949-1958
Data from several Huygens probe housekeeping sensors (an engineering accelerometer and housekeeping temperature sensors) are studied to determine how effectively such nonideal instruments may characterize the density or temperature structure of the atmosphere. While only confirming the results of the dedicated atmospheric structure instrument, this exercise is of relevance to possible future missions to various bodies which might not be equipped with such science-grade sensors able to accurately profile the atmosphere top-to-bottom. It is found that for typical engineering accelerometers with 8-bit resolution, the atmosphere density for ∼4 scale heights above the peak deceleration altitude may be recovered. If, as with Huygens, the peak deceleration exceeds the range of the accelerometers, recovery of an additional scale height or so below the peak is still possible, but relies on accurate total velocity knowledge. Engineering temperature sensors can, with care, be analyzed to recover the temperature structure of at least the lowest ∼30 km of Titan's atmosphere. Fortunately, in the case of Huygens, data from the surface after landing were available to constrain models of heat leaks which offset the observed temperature from that of the ambient air during descent; data from before and during the entry phase on other missions would be similarly useful. When corrections are made for the estimated heat transfer processes, the atmospheric temperature can be recovered to within about 3 K.  相似文献   

11.
Helium concentrations in the Martian atmosphere are estimated assuming that the helium production on Mars, comparable to its production on Earth, via the radioactive decay of uranium and thorium, is in steady state equilibrium with its thermal escape. Although non-thermal losses would tend to reduce the estimated concentrations, these concentrations are not necessarily an upper limit since higher production rates and/or a possibly lower effective exospheric temperature over the solar activity cycle could increase them to even higher values. The computed helium concentration at the Martian exobase (200 km) is 8 × 106 atoms cm?3. Through the lower exosphere, the computed helium concentrations are 30–200 times greater than the Mariner-measured atomic hydrogen concentrations. It follows that helium may be the predominant constituent in the Martian lower exosphere and may well control the orbital lifetime of Mars-orbiting spacecraft. The estimated helium mixing ratio is greater at the Martian turbopause than at the terrestrial turbopause, and the helium column density in the lower Martian atmosphere may be comparable to that on Earth.  相似文献   

12.
《Icarus》2002,159(2):433-438
Spacecraft have successfully landed on the Moon, Venus, and Mars, and have penetrated the atmosphere of Jupiter. On 2001 February 12, the Near-Earth Asteroid Rendezvous (NEAR) Shoemaker spacecraft landed on the surface of the asteroid (433) Eros after a year of observations in orbit about the asteroid. NEAR Shoemaker was not designed to land on an asteroid, complicating the design of operations needed to accomplish this feat. However, the NEAR Shoemaker team wanted to attempt a landing after the year of orbital operations that consumed most of the remaining spacecraft fuel, operations funding, and planned Deep Space Network tracking. This would be a fitting end to the mission, and it would be possible to obtain images at much greater resolution during the descent than could be obtained from orbit. The operations were more successful than the NEAR Shoemaker team had hoped, obtaining 70 high-resolution images during the descent and two weeks of gamma-ray spectrometer data from the surface after the successful soft landing.  相似文献   

13.
Parameterization of the spectral dependence of the optical characteristics of Martian aerosols has been proposed for processing the results of measurements of outgoing radiation. A method for retrieving the altitude profiles of the microphysical characteristics of Martian aerosols from the limb spectrometry of the OMEGA instrument of the Mars Express mission have been developed. For one of the observational sessions, the altitude profiles of the concentration and the modal radius of the size distribution function of aerosol particles retrieved with the proposed parameterization are presented. For the purpose of the interpretation of the data acquired from the optical remote sensing of planetary atmospheres, we consider how the spectral dependence of aerosol optical characteristics, in particular the volume coefficients of aerosol scattering and absorption and the phase function, can be parameterized in a specified, probably wide, spectral range. The method of such a parameterization has been proposed for the cases of a fixed chemical composition of the aerosol materials dominating in the atmosphere. It has been shown that these cases allow the required spectral dependences to be presented as a function of a small number of parameters, for which the parameters of the size distribution function of aerosol particles can be successfully used. However, since such direct calculations of the aerosol characteristics require an inadmissibly long period of time for the tasks of interpretation of the remote sensing data, an algorithm for organizing the parameterization function as a special, preliminary generated computer database has been suggested. This database provides the continuity in the dependence on the parameters, the specified computation accuracy, and the required output speed of the results. As a specific application, the parameterization of the spectral dependence of the optical characteristics of the Martian aerosols has been proposed for the tasks of processing the results of measurements of outgoing radiation. As a result, the method for retrieving the altitude profiles of the microphysical characteristics of Martian aerosols from the limb spectrometric measurements of the OMEGA instrument of the Mars Express mission has been developed. For one of the observational sessions, the altitude profiles of the concentration and the modal radius of the size distribution function of aerosol particles retrieved with the proposed parameterization are presented.  相似文献   

14.
The paper considers mathematical support for calculation of the aerodynamics and flight trajectory of descent vehicles (DV) during entry into the Martian atmosphere. The study of aerodynamics of a segmental and conical DV is given under various reentry conditions. The paper presents comparison of computational results of the aerodynamic properties of the DV of the ExoMars project with wind tunnel test data of DV models.  相似文献   

15.
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16.
W.G. Egan  T. Hilgeman  L.L. Smith 《Icarus》1978,35(2):209-226
Medium spectral resolution (20 cm?1) infrared measurements of the Martian disk made between 2900 and 5600 cm?1 from the NASA Lear Airborne Observatory have been successfully compared with predictions derived from a model of the Martian soil and atmosphere. Modeling of the Martian atmosphere permitted the extraction of Martian soil reflectance in the CO2 bands centered at 3657 cm?1. Three previously considered acceptable Martian soil analogs, limonite, montmorillonite, and basalt, were analyzed to determine the optical complex indices of refraction in the same range as the airborne observations, for mathematical modeling. A characteristic surface particle size ～1 to 3 μm diameter is indicated. It is concluded that the Martian soil surface near-infrared optical properties are consistent with a soil composition similar to montmorillonite or limonite, mixed with a basalt.  相似文献   

17.
A theoretical reconstruction of the history of Martian volatiles indicates that Mars probably possessed a substantial reducing atmosphere at the outset of its history and that its present tenous and more oxidized atmosphere is the result of extensive chemical evolution. As a consequence, it is probable that Martian atmospheric chemical conditions, now hostile with respect to abiotic organic synthesis in the gas phase, were initially favorable. Evidence indicating the chronology and degradational history of Martian surface features, surface mineralogy, bulk volatile content, internal mass distribution, and thermal history suggests that Mars catastrophically developed a substantial reducing atmosphere as the result of rapid accretion. This atmosphere probably persisted—despite the direct and indirect effects of hydrogen escape—for a geologically short time interval during, and immediately following, Martian accretion. That was the only portion of Martian history when the atmospheric environment could have been chemically suited for organic synthesis in the gas phase. Subsequent gradual degrassing of the Martian interior throughout Martian history could not sustain a reducing atmosphere due to the low intensity of planet-wide orogenic activity and the short atmospheric mean residence time of hydrogen on Mars. During the post-accretion history of Mars, the combined effects of planetary hydrogen escape, solar-wind sweeping, and reincorporation of volatiles into the Martian surface produced and maintained the present atmosphere.  相似文献   

18.
The hydrogen isotopic composition of planetary reservoirs can provide key constraints on the origin and history of water on planets. The sources of water and the hydrological evolution of Mars may be inferred from the hydrogen isotopic compositions of mineral phases in Martian meteorites, which are currently the only samples of Mars available for Earth‐based laboratory investigations. Previous studies have shown that δD values in minerals in the Martian meteorites span a large range of ?250 to +6000‰. The highest hydrogen isotope ratios likely represent a Martian atmospheric component: either interaction with a reservoir in equilibrium with the Martian atmosphere (such as crustal water), or direct incorporation of the Martian atmosphere due to shock processes. The lowest δD values may represent those of the Martian mantle, but it has also been suggested that these values may represent terrestrial contamination in Martian meteorites. Here we report the hydrogen isotopic compositions and water contents of a variety of phases (merrillites, maskelynites, olivines, and an olivine‐hosted melt inclusion) in Tissint, the latest Martian meteorite fall that was minimally exposed to the terrestrial environment. We compared traditional sample preparation techniques with anhydrous sample preparation methods, to evaluate their effects on hydrogen isotopes, and find that for severely shocked meteorites like Tissint, the traditional sample preparation techniques increase water content and alter the D/H ratios toward more terrestrial‐like values. In the anhydrously prepared Tissint sample, we see a large range of δD values, most likely resulting from a combination of processes including magmatic degassing, secondary alteration by crustal fluids, shock‐related fractionation, and implantation of Martian atmosphere. Based on these data, our best estimate of the δD value for the Martian depleted mantle is ?116 ± 94‰, which is the lowest value measured in a phase in the anhydrously prepared section of Tissint. This value is similar to that of the terrestrial upper mantle, suggesting that water on Mars and Earth was derived from similar sources. The water contents of phases in Tissint are highly variable, and have been affected by secondary processes. Considering the H2O abundances reported here in the driest phases (most likely representing primary igneous compositions) and appropriate partition coefficients, we estimate the H2O content of the Tissint parent magma to be ≤0.2 wt%.  相似文献   

19.
The isotopic composition of carbon dioxide in the Martian atmosphere from the measurements of Mars Science Laboratory have been used to estimate the relative abundances of CO2 isotopologues in the Martian atmosphere. Concurrently, this study has revealed long-standing errors in the amounts of some of low-abundance CO2 isotopologues in the Earth’s atmosphere in the databases of spectroscopic parameters of gases (HITRAN, etc.).  相似文献   

20.
Clouds and hazes composed of sulfuric acid are observed to exist or postulated to have once existed on each of the terrestrial planets with atmospheres in our solar system. Venus today maintains a global cover of clouds composed of a sulfuric acid/water solution that extends in altitude from roughly 50 km to roughly 80 km. Terrestrial polar stratospheric clouds (PSCs) form on stratospheric sulfuric acid aerosols, and both PSCs and stratospheric aerosols play a critical role in the formation of the ozone hole. Stratospheric aerosols can modify the climate when they are enhanced following volcanic eruptions, and are a current focus for geoengineering studies. Rain is made more acidic by sulfuric acid originating from sulfur dioxide generated by industry on Earth. Analysis of the sulfur content of Martian rocks has led to the hypothesis that an early Martian atmosphere, rich in SO2 and H2O, could support a sulfur-infused hydrological cycle. Here we consider the plausibility of frozen sulfuric acid in the upper clouds of Venus, which could lead to lightning generation, with implications for observations by the European Space Agency's Venus Express and the Japan Aerospace Exploration Agency's Venus Climate Orbiter (also known as Akatsuki). We also present simulations of a sulfur-rich early Martian atmosphere. We find that about 40 cm/yr of precipitation having a pH of about 2.0 could fall in an early Martian atmosphere, assuming a surface temperature of 273 K, and SO2 generation rates consistent with the formation of Tharsis. This modeled acid rain is a powerful sink for SO2, quickly removing it and preventing it from having a significant greenhouse effect.  相似文献   

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