Solar System Research最新文献

The lidar device as part of the meteorological complex of the ExoMars-2022 landing platform is designed to study Martian aerosol, the planetary boundary layer, and small-scale atmospheric turbulence. A miniature lidar based on a pulsed semiconductor laser and an avalanche photodiode in the photon counting mode will make it possible to obtain aerosol backscattering profiles along a vertical path from 10 to 1500 m during the day and from 15 to 10 000 m at night. In the passive mode, the sky brightness is measured in a narrow spectral range and in a narrow solid angle with a frequency of up to hundreds of hertz. The measured fluctuations can provide information about the turbulence of the daytime atmosphere and its relation to dust activity. In the paper we considered the scientific tasks of the experiment, the program of measurements on the surface of Mars and described in detail the components of the equipment and the features of their work.

The accelerometers and the angular velocity sensor, which are part of the meteorological complex of the ExoMars-2022 landing platform (LP), are designed to measure the acceleration during the deceleration of the lander in the Martian atmosphere. Based on the data, the main parameters of the Martian atmosphere are calculated: density, pressure, and temperature. After landing, the sensors are used to determine the acceleration on the surface and vibration effects on the lander of various nature. The sensors are activated prior to entry into the atmosphere and operate during the entire descent until landing. After landing, a long-term monitoring is carried out to identify vibration effects from the atmosphere and the surface. In the paper we consider the scientific problems solved by the sensors, describe the measurement program and consider in detail the design of the sensors and their characteristics.

A method has been developed for estimating the probability of an asteroid impact on the Earth. The method is based on the detection of impact orbit tubes in the initial confidence region, taking into account the nonlinearity in the problem of orbit determination. The method consists in sequential iteration of level surfaces of the minimized function and conditionally minimizing the distance from the asteroid to the Earth on them in some considered approach of the asteroid to the Earth. An approximate method has been developed for calculating the confidence level at any point in the initial region with a noticeable nonlinearity in the orbit determination problem. The impact risk is estimated by applying this method to the identified tube of impact orbits. The method has been tested for a number of potentially dangerous asteroids in their expected approaches to Earth.

The ExoMars programme has the objective to answer to the question of whether life ever existed on Mars. The second mission comprising the Rosalind Franklin rover and Kazachok Surface Platform was designed to focus specifically on the characterization of the environmental parameters which can play an important role for the existence of life on the surface of the planet. One of these parameters is the magnetic field because of its ability of shielding the solar and cosmic radiation. For such characterization, the scientific suite of the Surface Platform counts with two instruments: the Anisotropic MagnetoResistance (AMR) and the MArtIan Ground ElectromagneTic (MAIGRET) instruments. The AMR goal is to characterize both the surface and subsurface and the time-varying magnetic fields, related to the crustal and the external fields respectively, at the ExoMars landing site in Oxia Planum. The operation to achieve these goals includes two phases, the first phase corresponding to the lander descent and the second phase in which the instrument is deployed on the surface. In this work, we simulate the first operations phase using synthetic magnetic field models, assuming that the different crustal units at the landing site might be magnetized. We also perform measurements in our laboratory to simulate the second phase operation of the instrument on the Martian surface. We discuss the capability of interpretation of the instrument, based on the available information of the landing site and the results from our models.

The main focus of the present research work is to analyze the non-linear stability of the triangular equilibrium points ({{mathcal{L}}_{4}}) and ({{mathcal{L}}_{5}}) in the restricted three-body problem (R3BP). The condition of stability has been found out under the influence of the heterogeneous primary and a radiating finite-straight segment secondary and also under the effect by Coriolis as well as Centrifugal forces. This piece of research has been done by doing the normalization of the Hamiltonian in order to attained the Birkhoff’s normal form of the Hamiltonian, since normal forms of Hamiltonian are important to study the non-linear stability of equilibrium points. The conditions of KAM Theorem have been examined in the presence of resonance cases (omega _{1}^{'} = 2omega _{2}^{'}) and (omega _{1}^{'} = 3omega _{2}^{'}) and found that these conditions have been failed for three values of mass ratios ({{mu }_{1}},) ({{mu }_{2}}) and ({{mu }_{3}}.) Except these three values, ({{mathcal{L}}_{4}}) and ({{mathcal{L}}_{5}}) are stable in non-linear sense within the range of linear stability (0 < mu < {{mu }_{c}},) where ({{mu }_{c}}) is the critical value of mass parameter (mu .) Consequently, in the presence of above mentioned purturbations the triangular equilibrium points are unstable for these three values of mass ratios.

This research studies the O₂ (a¹Δ_g) nightglow distribution in 1.27 μm to understand the dynamics of the atmosphere of Venus. Several factors were considered in the retrieval process, such as thermal emission of the lower atmosphere, reflection by the clouds. Results show deviation from SS-AS circulation mode: the area where horizontal flows from the dayside converge and where oxygen recombines and emits shifts from the midnight to 22–23 hours local time. This shift is caused by solar-induced thermal tide on Venus nightside. Some conclusions about the upper mesosphere dynamics are also presented.

Estimates of the size of the feeding zone of the planet Proxima Centauri c have been made at initial orbital eccentricities of planetesimals equal to 0.02 or 0.15. The research is based on the results of modeling of the evolution of planetesimals’ orbits under the influence of the star and planets Proxima Centauri c and b. The considered time interval reached a billion years. It was found that after the accumulation of the planet Proxima Centauri c some planetesimals may have continued to move in stable elliptical orbits within its feeding zone, largely cleared of planetesimals. Usually such planetesimals can move in some resonances with the planet (Proxima Centauri c), for example, in the resonances 1 : 1 (as Jupiter Trojans), 5 : 4 and 3 : 4 and usually have small eccentricities. Some planetesimals that moved for a long time (1–2 million years) along chaotic orbits fell into the resonances 5 : 2 and 3 : 10 with the planet Proxima Centauri c and moved in them for at least tens of millions of years.