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Force-System Resultants and Equilibrium
Published in Richard C. Dorf, The Engineering Handbook, 2018
Every spacecraft must be able to survive in several environments. All those built on earth must be able to survive the earth’s atmosphere or be protected from it. The Earth’s standard atmosphere is described in Chapter 198, and atmosphere models for other planets are available in NASA literature. The launch environment, characterized by vibration, noise, g-loads, aerodynamic loads, transition from air to vacuum, and so on, constitutes a major test for spacecraft. The space environment presents another set of problems for the designer. Hard vacuum, radiation, and temperature extremes are common to all missions. Spacecraft that fly through or beyond the Van Allen radiation belts experience more severe radiation hazards than those spacecraft that stay inside the Van Allen belts. For manned spacecraft, extended flight beyond the protection of the Van Allen belts implies special crew radiation shielding. Orbital debris is also a hazard that must be considered.
Nucleosynthesis, Cosmic Radiation, and the Universe
Published in Ivan G. Draganić, Zorica D. Draganić, Jean-Pierre Adloff, Radiation and Radioactivity on Earth and Beyond, 2020
Ivan G. Draganić, Zorica D. Draganić, Jean-Pierre Adloff
The maximum energy of a solar ray is of the order of 0.1 gigaelectronvolt, or even higher in the case of exceptionally strong flares. On the average, however, the energies of typical solar protons are lower and are found mainly in the kiloelectronvolt range. These particles cannot penetrate the atmosphere and therefore do not reach the surface of the Earth. Part of the solar wind remains trapped in the Earth’s magnetic field and forms the outer Van Allen radiation belt. Other, more energetic solar protons, penetrate the upper atmosphere and accumulate in narrow zones in the region of the Earth’s magnetic poles, producing the well-known auroral displays.
Terra, Our Earth
Published in Thomas Hockey, Jennifer Lynn Bartlett, Daniel C. Boice, Solar System, 2021
Thomas Hockey, Jennifer Bartlett, Daniel Boice
Energetic particles trapped by the terrestrial magnetic field are harmful radiation. Zones around the Earth with dense concentrations of this radiation are named the Van Allen Radiation Belts, after American physicist James Van Allen 〈1914–2006〉 who discovered them using a radiation detector aboard the first US artificial satellite, Explorer 1, in 1958. They have practical significance. Astronauts traveling to the Moon, for instance, must not spend too much time in these Belts lest they suffer from biological damage by radiation exposure (Figure 7.10).
Quantitative effects of cyclotron resonance on the coupling of ULF with VLF and langmuir waves
Published in Waves in Random and Complex Media, 2021
Asif Shah, Shahzad Mahmood, Saeed Ur Rehman
To evaluate the role of electron cyclotron resonance on the turbulent coupling of ULF, VLF and Langmuir waves, the coupling coefficients and dispersion coefficients are determined for various sets of pitch angles and kinetic energies of the resonant electrons. Figure 1 shows the equatorial magnetic field strength with distance from center of Earth. In the inner Van-Allen radiation belt (, here the distances are described in terms of Earth's radius denoted by ), the magnetic field varies from and it ranges from 400 to 120 nT in the outer Van-Allen radiation belt (). The magnetic field strength varies from 30 to 1 nT in the magneto tail region (). In the following figures, the ambient magnetic field values are mostly comparable to those in the magneto tail. Therefore, the findings of this work are applicable to wave–wave and wave-particle resonant couplings in the magneto tail region of Earth's magnetosphere.