Deformation of the Envelope of a Broadband Signal during Propagation through the Martian Ionosphere

The regularities of propagation along the spacecraft-Martian surface-spacecraft path of a broadband Gaussian pulse in the condition of its dispersion distortions are considered in application to the problem of radiowave pulse sounding of the near-surface soil of Mars from onboard a satellite. The Martian night-side ionosphere reduces the energy considerably but does not lead to any distortion of the pulse envelope. At the sounding of a two-layer surface, the ionosphere influence, together with the signal absorption, manifests as the lower limit of the thickness of the upper layer reached for measurements in the scope of the planned experiment [1].     

Using the Subsurface Soil Sounding Radar for Investigating the Structure and Total Electron Content of the Martian Ionosphere

The possibilities of using the Martian soil subsurface sounding radar for investigating the structure of the plasma shell surrounding the planet have been considered. Based on the numerical modeling results and actual soil sounding data, it has been shown that the soil sounding mode of the radio-locating MARSIS radar can be used to assess the structure of the Martian ionosphere. As the emitted signals pass to the planet’s surface, it is possible to use the reflected signals to estimate the total electron content of the Martian ionosphere along the flight track of the spacecraft.     

Exploration of Mars in the SPICAM-IR experiment onboard the Mars-Express spacecraft: 2. Nadir observations: Simultaneous observations of water vapor and O2 glow in the Martian atmosphere

The SPICAM experiment onboard the Mars-Express spacecraft includes sounding the Martian atmosphere in the ultra-violet (118–320 nm) and near IR (1–1.7 μm) ranges. The infrared spectrometer operates in the range of 1–1.7 μm with a resolution of 3.5 cm^?1 in the mode of nadir observations and solar and stellar occulations. This paper is devoted to analyzing the basic results of nadir observations of the infra-red SPICAM channel during the first Martian year of the instrument operation: from January 2004 to November 2005. One of the primary goals of SPICAM-IR is water vapor monitoring in the atmosphere of Mars in the band of 1.37 μm and ozone abundance determination from the day-time airglow of molecular oxygen O₂(a ¹Δ_g) in the band of 1.27 μm. Simultaneous measurements of these minor constituents of the planet are necessary for understanding photochemical processes in the Martian atmosphere. The degree of their anticorrelation and a comparison with the results of photochemical modeling of the atmosphere will contribute to our knowledge of the Martian atmosphere stability.     

Radar sounding of Mars from the orbit of the Mars-Express automatic interplanetary station

On the base of the laser altimetry results obtained using the orbital altimeter MOLA (the MGS mission) and the data of radio occultation experiments of transionospheric sounding of the Mars ionosphere, a method for interpretation of the planet radar sounding data is developed. The proposed method includes a program package for numerical simulation of the process of radiowave propagation through the media under study.     

Influence of anisotropic fluctuations of the ionosphere plasma density on deep radio sounding by a ultra wide band radar with synthesized aperture

The problem of deep sounding of planet interior using ultra wide band radar with synthesized aperture is considered for the case when anisotropic fluctuations of the ionosphere plasma density take place. Modeling is performed for a number of values of the medium and radar characteristic parameters. The degree of influence of mutual orientation of the anisotropy direction of ionospheric fluctuations and of the spacecraft flight trajectory is estimated. It is demonstrated that widening of radar pulses is determined by characteristic spatial scale of ionosphere plasma disturbances in the transverse direction relative to the spacecraft flight trajectory. On the other hand, attenuation of the peak power of the pulses is shown to be determined basically by the longitudinal scale of disturbance correlations.     

On the amplitude of low-frequency signals in the nighttime ionosphere over thunderstorm discharges

It is shown that the origin of anomalous amplitudes of ULF/ELF signals in the topside ionosphere over thunderstorm discharges could be caused by the existence of regions of highly-ionized plasma in the lower ionosphere. The alternating current of the lightning electromagnetic pulse can generate in the region of highly-ionized plasma formed in the lower ionosphere due to the influence of thunderstorm discharges magneto-hydrodynamic waves propagating into the topside ionosphere. On the basis of the suggested model, the estimates of amplitude and duration of the Alfven mode propagating into the topside ionosphere are obtained, which agree with the measurements in rocket experiments over thunderstorms.     

Spatial–Temporal Characteristics of Large Scale Disturbances of Electron Density Observed in the Ionospheric F-Region before Strong Earthquakes

The spatial dimensions and temporal dynamics of large scale disturbances of electron density in the ionospheric F-region during the preparatory phase of destructive earthquakes are estimated. The most appropriate data (as far as the moments of satellite passages are concerned) were selected out of more than 300 investigated cases. In order to demonstrate effects at different latitudes, the cases of high-latitude (Alaska), mid-latitude (Central Italy), and low-latitude (New Zealand) earthquakes were considered. Using the data of external vertical sounding of the ionosphere performed by the Alouette-1 and Interkosmos-19 satellites together with the data of vertical sounding of the ionosphere by ground-based instruments, we get for the first time with reasonable accuracy the spatial characteristics of precursors in the ionosphere. It is shown that seismic ionospheric disturbances are strongly time-dependent before the beginning of the main shock. Seismic ionospheric disturbances are generated weakly several days before the first shock, but at that moment the disturbed region is located not above the epicenter, but rather a little displaced from it. As the moment of the earthquake approaches, the disturbance covers more and more space; moreover, its value also increases. Several hours after the shock the disturbance migrates in the reverse order. Under some conditions, the disturbances may appear not only above epicenter regions. They can be transferred along the magnetic field lines into conjugate regions in the opposite hemisphere.     

Variations in the Parameters of Radio Waves in the Earth’s High-Latitude Ionosphere on the Satellite–Satellite Paths during the Geomagnetic Storm of June 22–23, 2015

Cosmic Research - This paper analyzes the results of about 100 radio occultation sessions of sounding of the high-latitude (>65 °N) lower ionosphere of the Earth’s Northern...     

Electromagnetic sounding of planets from a low-orbiting probe

Is it theoretically possible to perform magnetotelluric sounding in order to determine the conductivity of a planet’s interior based on the registration of variable electric and magnetic fields on a low-orbiting space probe? In this case, fast magnetosonic (FMS) waves in the planetary magnetosphere can play the role of sounding waves. It has been indicated that the registration of FMS-wave impedance (the ratio of the electric and magnetic components) onboard the probe actually makes it possible to estimate the planetary conductivity for a planet with a magnetosphere and ionosphere.     

On the Accuracy of the Conjugation of High-Orbit Satellites with Small-Scale Regions in the Ionosphere

The degree of uncertainty that arises when mapping high-orbit satellites of the Cluster type into the ionosphere using three geomagnetic field models (T89, T98, and T01) has been estimated. Studies have shown that uncertainty is minimal in situations when a satellite in the daytime is above the equatorial plane of the magnetosphere at the distance of no more than 5 R_E from the Earth’s surface and is projected into the ionosphere of the northern hemisphere. In this case, the dimensions of the uncertainty region are about 50 km, and the arbitrariness of the choice of the model for projecting does not play a decisive role in organizing satellite support based on optical observations when studying such large-scale phenomena as, e.g., WTS, as well as heating experiments at the EISCAT heating facility for the artificial modification of the ionosphere and the generation of artificial fluctuations in the VLF band. In all other cases, the uncertainty in determining the position of the base of the field line on which the satellite is located is large, and additional information is required to correctly compare the satellite with the object in the ionosphere.     

The Martian and extraterrestrial UV radiation environment. Part II: further considerations on materials and design criteria for artificial ecosystems.

Ultraviolet radiation is an important natural physical influence on organism function and ecosystem interactions. The UV radiation fluxes in extraterrestrial environments are substantially different from those experienced on Earth. On Mars, the moon and in Earth orbit they are more biologically detrimental than on Earth. Based on previously presented fluxes and biologically weighted irradiances, this paper considers in more detail measures to mitigate UV radiation damage and methods to modify extraterrestrial UV radiation environments in artificial ecosystems that use natural sunlight. The transmission characteristics of a Martian material that will mimic the terrestrial UV radiation environment are presented. Transmissivity characteristics of other Martian and lunar materials are described. Manufacturing processes for the production of plastics and glass on the lunar and Martian surface are presented with special emphasis on photobiological requirements. Novel UV absorbing configurations are suggested.     

The BOSS and BIOMEX space experiments on the EXPOSE-R2 mission: Endurance of the desert cyanobacterium Chroococcidiopsis under simulated space vacuum,Martian atmosphere,UVC radiation and temperature extremes.

The proposed space experiments BOSS (Biofilm Organisms Surfing Space) and BIOMEX (BIOlogy and Mars experiment) will take place on the space exposure facility EXPOSE-R2 on the International Space Station (ISS), which is set to be launched in 2014. In BOSS the hypothesis to be tested is that microorganisms grown as biofilms, hence embedded in self-produced extracellular polymeric substances, are more tolerant to space and Martian conditions compared to their planktonic counterparts. Various microbial biofilms have been developed including those obtained from the cyanobacterium Chroococcidiopsis isolated from hot and cold deserts. The prime objective of BIOMEX is to evaluate to what extent biomolecules are resistant to, and can maintain their stability under, space and Mars-like conditions; therefore a variety of pigments and cell components are under investigation to establish a biosignature data base; e.g. a Raman spectral library to be used for extraterrestrial life biosignatures. The secondary objective of BIOMEX is to investigate the endurance of extremophiles, focusing on their interactions with Lunar and Martian mineral analogues. Ground-based studies are currently being carried out in the framework of EVTs (Experiment Verification Tests) by exposing selected organisms to space and Martian simulations. Results on a desert strain of Chroococcidiopsis obtained from the first set of EVT, e.g. space vacuum, Mars atmosphere, UVC radiation, temperature cycles and extremes, suggested that dried biofilms exhibited an enhanced survival compared to planktonic lifestyle. Moreover the protection provided by a Martian mineral analogue (S-MRS) to the sub-cellular integrities of Chroococcidiopsis against UVC radiation supports the endurance of this cyanobacterium under extraterrestrial conditions and its relevance in the development of life detection strategies.     

Multi-frequency doppler radio sounding of the ionosphere in the “Equatorial trigger” experiment

Results of processing the data of multi-frequency Doppler sounding of the low-latitude ionosphere are presented. Interesting features in the behavior of time variations of the Doppler frequency shift are found. These features are interpreted as manifestations of wave disturbances in the ionospheric plasma density.     

Aladdin mission concept

Aladdin, one of five Concept Study winners for NASA's Discovery AO98-OSS-04, was a mission to obtain samples from the two Martian moons using several unique mission design and sample collection techniques. The mission design enabled sample return from two bodies at the relatively low cost of a Discovery-class mission. It featured a phasing orbit, multiple flybys of the Martian moons, and a short overall mission duration. The phasing orbit greatly reduced the post-launch Δv requirement, thus permitting the use of a Delta II launch vehicle. Multiple moon flybys provided ample opportunities for sample collection and science observations. The short overall mission duration reduced program costs. Aladdin's sample collection, unlike traditional sample collection methods, used a “launch-and-catch” technique to obtain samples. Projectiles would be launched to the moon's surface during a close flyby and the ejected particles gathered for Earth return and analysis. This innovative technique, the Aladdin mission, and the possible extension of the technique to other bodies are described.     

Space charge sheath formation in a magnetized plasma flow around space bodies

Space charge sheath formation in a magnetized plasma flow around space bodies is considered for the cases of high surface conductivity, free electron emission, dipole magnetic field. The results are applied to explain different phenomena in the ionosphere and magnetosphere of the Earth and planets such as polar aurora and kilometric radiation of the Earth and decametric radiation of the Jovian satellite Io.     

Venus Express: Scientific goals, instrumentation, and scenario of the mission

The first European mission to Venus (Venus Express) is described. It is based on a repeated use of the Mars Express design with minor modifications dictated in the main by more severe thermal environment at Venus. The main scientific task of the mission is global exploration of the Venusian atmosphere, circumplanetary plasma, and the planet surface from an orbiting spacecraft. The Venus Express payload includes seven instruments, five of which are inherited from the missions Mars Express and Rosetta. Two instruments were specially designed for Venus Express. The advantages of Venus Express in comparison with previous missions are in using advanced instrumentation and methods of remote sounding, as well as a spacecraft with a broad spectrum of capabilities of orbital observations.     

Martian polar expeditions: problems and solutions.

The Martian polar ice caps are regions of substantial scientific interest, being the most dynamic regions of Mars. They are volatile sinks and thus closely linked to Martian climatic conditions. Because of their scale and the precedent set by the past history of polar exploration on Earth, it is likely that an age of polar exploration will emerge on the surface of Mars after the establishment of a capable support structure at lower latitudes. Expeditions might be launched either from a lower latitude base camp or from a human-tended polar base. Based on previously presented expeditionary routes to the Martian poles, in this paper a "spiral in-spiral out" unsupported transpolar assault on the Martian north geographical pole is used as a Reference expedition to propose new types of equipment for the human polar exploration of Mars. Martian polar "ball" tents and "hover" modifications to the Nansen sledge for sledging on CO2-containing water ice substrates under low atmospheric pressures are suggested as elements for the success of these endeavours.Other challenges faced by these expeditions are quantitatively and qualitatively addressed.     

“嫦娥三号”探测器月尘环境分析及试验要求

"嫦娥三号"是我国首个成功实施地外天体表面就位探测的航天器,在其研制过程中充分考虑了月面环境对探测器的影响,开展了针对性设计及地面验证工作。文章综述了探测器针对月尘环境方面的设计因素,总结了月面月尘激扬的因素及其相关数值分析工作,对月尘验证试验的设计及条件制定进行了说明。相关结果或工作思路可为后续月面探测器及火星表面探测器的研制提供参考。     

Electromagnetic Pulse in the Magnetosphere Generated by Impulsive Current near the Lower Boundary of the Ionosphere

A solution to the problem of current spreading is constructed in the case of relaxation of electric charges, which have arisen in the mesosphere for one reason or other. These currents penetrate into the conductive region with anisotropic conductivity of the D- and E-layers of the ionosphere, being transformed to a MHD-wave that propagates into the magnetosphere. Based on this solution, the form and spectrum of the generated MHD signal are calculated for Alfvenic and magnetosonic modes coming out to the ionosphere and magnetosphere. Electric charges and currents can arise, for example, in the space between a thunderstorm cloud and the ionosphere, or between the shock wave from a ground explosion and the ionosphere. Some signal parameters accepted in the model are close to those expected for high-altitude electric discharges of the Red Sprite type. The conditions are determined under which the Alfven impulse with an amplitude of up to 100 nT propagates in the magnetosphere above high-altitude discharge of this type. Such an impulse was recorded by the AUREOL-3 satellite after the ground explosion MASSA-1. Recently, this impulse was hypothesized to originate as a result of a high-altitude electric discharge. The hypothesis on a similar MHD pulse allows one to explain in a semiquantitative way the short burst of electron field-aligned acceleration observed by the DE-2 satellite over the Debbie hurricane. The high-altitude atmospheric discharge of this type can be a powerful, though short-time and local, source of electrons with kiloelectronvolt energies at low and middle latitudes. One could expect that such an effect causes a modified character of the so-called Trimpi-effect (a short-term disturbance of propagation of VLF waves in the ionosphere), and thus, it can be observable.     

The Influence of artificial plasma irregularities on the propagation of VLF waves in the Earth’s magnetosphere

In the framework of the approximation of geometric optics, the peculiarities of VLF-wave propagation in the Earth’s ionosphere and magnetosphere during the creation of large-scale artificial plasma irregularities by heating facilities such as HAARP and “Sura” in the ionosphere are studied. For calculation of ray trajectories, the profile of the concentration and ion composition of plasma is taken by calculating the SAMI2 ionospheric model, which was modified to take the influence on the ionosphere of the HF emissions of heating facilities into account. As a result of the influence of the heating facilities on the ionosphere, a region could occur with an increased plasma concentration that is stretched out along the geomagnetic field (up to heights on the order of the Earth’s radius) with small dimensions across the field (～1°). The ray trajectories of waves that propagate from heights of about 100 km from different initial points in the region where such a disturbance has been created with different initial inclination angles of the wave normal are studied in this paper. Both lightning discharges and modulated HF heating of the ionosphere could be the sources of such waves. It is shown on the basis of the performed analysis that the presence of such disturbances in density can lead to a substantial changes in wave-propagation trajectories, in particular, to efficient channeling of VLF waves in the disturbance region and an increase in the interval of the initial propagation angles of waves, which can reach the ionosphere in the opposite hemisphere.