The Juno Waves Investigation

Jupiter is the source of the strongest planetary radio emissions in the solar system. Variations in these emissions are symptomatic of the dynamics of Jupiter’s magnetosphere and some have been directly associated with Jupiter’s auroras. The strongest radio emissions are associated with Io’s interaction with Jupiter’s magnetic field. In addition, plasma waves are thought to play important roles in the acceleration of energetic particles in the magnetosphere, some of which impact Jupiter’s upper atmosphere generating the auroras. Since the exploration of Jupiter’s polar magnetosphere is a major objective of the Juno mission, it is appropriate that a radio and plasma wave investigation is included in Juno’s payload. This paper describes the Waves instrument and the science it is to pursue as part of the Juno mission.     

Geomagnetic Observations for Main Field Studies: From Ground to Space

Direct measurements of the geomagnetic field have been made for more than 400 years, beginning with individual determinations of the angle between geographic and magnetic North. This was followed by the start of continuous time series of full vector measurements at geomagnetic observatories and the beginning of geomagnetic repeat stations surveys in the 19th century. In the second half of the 20th century, true global coverage with geomagnetic field measurements was accomplished by magnetometer payloads on low-Earth-orbiting satellites. This article describes the procedures and instruments for magnetic field measurements on ground and in space and covers geomagnetic observatories, repeat stations, automatic observatories, satellites and historic observations. Special emphasis is laid on the global network of geomagnetic observatories.     

Optimimal control of CNC machine operating regimes

In this paper, a mathematical model of labor-intensity and a method of searching for optimal control of operating conditions in machining arbitrarily configurated parts with the use of CNC machines are considered. Also given is an example of the process optimization..     

Analysis of structural elements made of composite materials with defects

The paper presents an improved technique and the results of strength analysis for the aircraft structural elements with a structural defect like an arbitrary shape delamination.     

Analysis of the spacecraft vertical landing dynamics on the platform with crash legs

This paper proposes a novel landing gear for spacecraft that allows a weight reduction due to using deformable crash legs. Numerical simulation of the landing process was performed.     

Flux and isotopic composition of helium in the ancient solar wind

The isotopic composition and concentrations of helium are investigated in 9 samples taken from different depths of a soil column delivered by the Luna-24 mission. It is demonstrated that, with allowance made for random errors, the isotopic composition of helium remains invariable. The concentrations of helium are subject to considerable variations, the increases and decreases relative to the average value reaching a factor of 1.5–2. Assuming that the full length of the soil column was formed due to long-term accumulation of lunar clastic rocks (regolith), based on measurements of cosmogenic isotopes, a method of determining the rate of regolith accumulation has been developed, as well as a method of determining the age of the column soil samples. It is found that the rate of regolith accumulation is variable, and it changes over the column length within the limits (0.2–0.8 cm)/10⁶ years. The range of the time for formation of the investigated part of the column is 100–600 million years. The observed decreases of concentration (at 250 and 600 million years) can be associated with both solar and lunar processes. In particular, a possibility of diffusion losses of helium due to the mechanism of jump-like diffusion is discussed, and diffusion parameters are found. A comparison of time periods of the observed variations in the solar wind with paleontological epochs and periods is made.     

Active debris removal of multiple priority targets

Today’s space debris environment shows major concentrations of objects within distinct orbital regions for nearly all size regimes. The most critical region is found at orbital altitudes near 800 km with high declinations. Within this region many satellites are operated in so called sun-synchronous orbits (SSO). Among those, there are Earth observation, communication and weather satellites. Due to the orbital geometry in SSO, head-on encounters with relative velocities of about 15 km/s are most probable and would thus result in highly energetic collisions, which are often referred to as catastrophic collisions, leading to the complete fragmentation of the participating objects. So called feedback collisions can then be triggered by the newly generated fragments, thus leading to a further population increase in the affected orbital region. This effect is known as the Kessler syndrome.     

Cosmic-Ray Energy Spectra and Time Variations in the Local Interstellar Medium: Constraints and Uncertainties

The spectra of galactic cosmic rays that are observed inside the heliosphere result from the interaction of the spectra present in the local interstellar medium with the structured but turbulent magnetic field carried by the solar wind. Observational tests of solar modulation theory depend on comparisons between spectra inside and outside the heliosphere. Our knowledge of the local interstellar spectra are indirect, using extrapolations of interplanetary spectra measured at high energies where solar modulation effects are minimal and modeling of the physical processes that occur during particle acceleration and transport in the interstellar medium. The resulting estimates of the interstellar spectra can also be checked against observations of the effects that cosmic rays have on the chemistry of the interstellar medium and on the production of the diffuse galactic gamma-ray background. I review the present understanding of the local galactic cosmic-ray spectra, emphasizing the constraints set by observations and the uncertainties that remain.     

Buckling of composite panels: A criterion for optimum stiffener design

In this paper a linear, closed-form analysis of the buckling behavior of an orthotropic plate with elastic clamping and edge reinforcement under uniform compressive load is presented. This is a typical structural situation found in aerospace engineering for instance as stiffeners in wings or the fuselage. All governing equations are transformed in a dimensionless system using common characteristic quantities to gain good analytical access. The buckling behavior is analyzed and generic buckling diagrams are presented. The solutions show excellent agreement with results from literature and numerical analyses.The minimum bending stiffness of the edge reinforcement needed to withstand buckling is examined and a minimum stiffness criterion is presented. Furthermore an absolute minimum bending stiffness is found which is sufficient to enable the reinforcement to act as a near-rigid support for arbitrarily long plates. These criteria are of interest for optimized lightweight design of stringers and stiffeners.