Особенности перемещения криоботов в ледяных структурах Европы
The influence of different forms of housing cryobot speed and efficiency of movement them into the ice structures. The problems of cryobot to study the ice surface in Europe
The exploration of icy satellites such as Saturn’s moon Enceladus or Jupiter’s moons Europa and Ganymede is one of the popular branches in modern space research. Each icy body has its own feature: water ice presence on Enceladus, cryo-vulcanism on Ganymede, Europa’s smooth shell. Also conditions on these moons allow speculation about possible life, considering these moons from an astrobiological point of view.
Research in the last decade shows that there should be a deep ocean (the estimated thickness varies up to 100km) under the icy sheet of Europa. The estimated thickness of the ice on Ganymede varies up to 800km. To study this possible ocean and to look for life’s traces, it is necessary to penetrate the icy sheet. This means that special equipment should be designed. On the Earth, similar kinds of probes have been used successfully to study glaciers. Use of such probes enables extrapolation from terrestrial to extraterrestrial application.
There are several ways to penetrate through the ice. The authors consider these possibilities and explain why, in the case of exploration of icy moons, a melting probe is preferred.
Other unsolved problems are in the areas of analyzing how the probe will move in low gravity and low atmospheric pressure; whether the hole formed in the ice will be closed when the probe penetrates far enough or not; what is the influence of the probe’s characteristics on the melting process; and what would be the order of magnitude of the penetration velocity. This study explores the technique based on elasto-plastic theory and so-called “solid water” theory to estimate the melting velocity and to study the melting process. Based on this technique, the authors considered several cases of melting probe motion, estimated the velocity of the melting probe, studied and discussed the influence of different factors, and propose an easy way to optimize the parameters of the probe.
Nowadays planetary bodies' studies are of the great interest. First of all, such space objects are the icy moons of the giant planets like Jupiter and Saturn. Of particular interest is the relatively smooth Europa's surface that is covered by a bands system, valleys, and ridges. To study the planetary icy body in future space missions, one of the problems to solve is the problem of design of a special device, capable to penetrate through the ice, as well as the choice of the landing site of this probe. To select possible landing site analysis of the Europa's surface relief formation is studied. This analysis showed that the compression, extending, shearing, and bending can influence on some arbitrarily separated section of Europe's icy surface. The computer simulation with finite element method (FEM) was performed to see, what types of defects could arise from such effects. Also the problem of melting probe movement through the ice is considered: how the probe will move in low gravity and low atmospheric pressure; whether the hole formed in the ice will be closed when the probe penetrates far enough or not; what is the influence of the probe's characteristics on the melting process; what would be the order of magnitude of the penetration velocity. This study explores the technique based on elasto-plastic theory and so-called “solid water” theory to estimate the melting velocity and to study the melting process. Based on this technique, several cases of melting probe motion are considered, the velocity of the melting probe is estimated, the influence of different factors are studied and discussed, and an easy way to optimize the parameters of the probe is proposed.
In modern space science one of the actual branches is icy satellites explorations. The main interest is concentrated around Jovian’s moons Europa and Ganymede, Saturn’s moons Titan and Enceladus that are covered by thick icy layer according to “Voyager1”, “Voyager2”, “Galileo” and “Cassini” missions. There is a big possibility that under icy shell could be a deep ocean. Also conditions on these satellites allow speculating about possible habitability, and considering these moons from an astrobiological point of view.
One of the possible tasks of planned missions is a subsurface study. For this goal it is necessary to design special equipment that could be suitable for planetary application. One of the possible means is to use a melting probe which operates by melting and moves by gravitational force. Such a probe should be relatively small, should not weight too much and should require not too much energy. In terrestrial case such kind of probe has been successfully used for glaciers study. And it is possible to extrapolate the usage of such probe to extraterrestrial application.
One of the tasks is to estimate melting probe’s penetration velocity. Although there are other unsolved problems such as analyzing how the probe will move in low gravity and low atmospheric pressure; knowing whether hole will be closed or not when probe penetrate thick enough; and considering what order could be a penetration velocity. This study explores two techniques of melting probe’s movement. One of them based on elasto-plastic theory and so-called “solid water” theory, and other one takes phase changing into account. These two techniques allow estimating melting probe’s velocity range and study whole process. Based on these technique several cases of melting probe movement were considered, melting probe’s velocity range estimated, influence of different factors studied and discussed and an easy way to optimize parameters of the melting probe proposed.
This aim of this paper is the interpretation of the results of mechanical testing of materials to determine their properties under hot deformation. As an example, a simulation of rod stretching in superplasticity mode was considered. Comparing obtained data with the analytical solution was conducted.
We discuss the materials associated with the formation of chaotic bands on the ice surface on Europe, a satellite of Jupiter. There are suggestions as to their origin.