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Thermal and Mechanical Design
Published in Shen-En Qian, Hyperspectral Satellites and System Design, 2020
Hyperspectral satellites are three-axis stabilized spacecraft. The same basic approach to thermal control for this kind spacecraft can be used to hyperspectral satellites, though radioactive heating may be necessary. For instance, the spacecraft is insulated from the space environment with MLI blankets, and radiator areas with low solar absorption and high infrared emittance are provided to dissipate waste heat. Wavelength-dependent surface finishes or coatings are adopted for various thermal control purposes. Solar reflector materials, including white paints, or silver- or aluminum-backed Teflon are used to minimize absorbed solar energy. Inside a spacecraft black paints are commonly used if it is desired to exchange energy with the compartment or other devices. Components mounted inside the spacecraft on the shelves, panels, and structures radiate their waste heat to the outside walls of the spacecraft, where the heat is dissipated to space.
Compendium of NASA’s COTS Radiation Test Data
Published in John D. Cressler, H. Alan Mantooth, Extreme Environment Electronics, 2017
NASA spacecraft are subjected to a harsh space environment that includes exposure to various types of ionizing radiation. Long-term exposure to radiation has been known to affect the function of the spacecraft electronics. As a result, flight parts must be tolerant to radiation-induced TID and DD effects or parts must be mitigated by shielding or other methods to reduce radiation effects.
National Security Space
Published in M. Ann Garrison Darrin, Patrick A. Stadter, Aerospace Project Management Handbook, 2017
Space as a domain, has several unique characteristics that must be addressed when planning for operations:To date, there are no geographical boundaries in space. International law does not extend a nation’s territorial sovereignty up to Earth orbit. Therefore, nations enjoy unimpeded satellite over flight of other nations in space.Movement in space is governed by orbital mechanics. Satellite orbits must follow certain orbital parameters due to the laws of physics. A satellite’s orbit can be customized to best satisfy a satellite’s mission. Once a satellite’s orbit is selected, it is not usually changed because any change of orbit maneuvers can deplete propellant, which can significantly degrade the performance or life-span of a system.The space environment, itself, can be a significant limiting factor affecting the performance and life-span of any operational spacecraft. Apart from the threat of meteorites, almost many hazards to space capabilities come from the sun. The various phenomena resulting from the sun’s activity are collectively termed “space weather” and manifest as increased radiation dosages, electromagnetic noise, ionospheric interference, or prolonged impact by energetic charged particles. Solar flares charged particles, cosmic rays, the Van Allen radiation belts, and other natural phenomena in space can affect communications, navigation accuracy, sensor performance, and even cause electronic failure.Operational satellites are under constant threat of impact by space debris. Space debris includes a myriad of phenomena including orbiting particulates left behind during a satellite’s lifetime, debris from satellite explosion, or impacts, orbiting “trash” such as rocket bodies or natural objects such as meteoroids. Collisions with space debris can damage or utterly destroy space systems.Space-based assets depend on the electromagnetic spectrum (EMS) as their sole means for transmitting and receiving information and/or signals. The electromagnetic frequency bands that satellites use are fixed during development and cannot be changed after launch. It is vital that the U.S. forces achieve EMS control to ensure freedom of action for space assets [3].
A Review of Vapor Chambers
Published in Heat Transfer Engineering, 2019
Murat Bulut, Satish G. Kandlikar, Nedim Sozbir
A space environment is different from a terrestrial environment, because it differs in such elements as the vacuum condition, zero gravity, vibration and shock, etc. Light-weight, high performance, low cost, reliability, etc., are also priorities for the really important design parameters not only for HPs but also VCs in space applications. Therefore, researchers involved in space application are more attentive not only to improving technology but also to making sure that the technology will survive in a space environment for a long time without any problems.
Irradiation effects of 6 mev-electrons on optical and electrical properties of TiO2/Al2o3 multilayer thin films
Published in Radiation Effects and Defects in Solids, 2021
P. Laha, S. K. Mahapatra, I. Banerjee, V. N. Bhoraskar
Multilayer, transparent optical coatings play an important role in the development of efficient, light weight, flexible solar power arrays for future space applications (1–3). Thin-film coatings act as protective layers to protect substrates against damage from hazardous space environment. In recent years, the aeronautics and space research industry explored various prototype designs and ways of protecting silicone Fresnel lenses, solar cells from the severe UV radiation (2–5). Commonly, it is considered that the space environment imposes benevolent influences on optical devices and their coatings compare to the earth’s surface under environmental stresses. For space applications coatings must tolerate and survive in numerous environmental requirements. The space environment poses various radiation damages from micro-meteorite, vacuum exposure and thermal exposure which depends on the orbital properties of space missions. Generally, solar cell power generating panels are exposed directly in a space environment which causes optical damage or transmission loss caused by the energetic irradiation from electrons and protons. Previously, to protect the silicone lenses from solar UV darkening, cerium doped glass covers over the lens were used (6). Due to ambient radiation, the glass lens covers are cracked during launch simulation shock testing. This failure has initiated the coating of a silicone lens surface with UV absorbent thin films. Presently, multifunctional smart optical coatings have been used in space instrument applications. TiO2 and Al2O3 are wide bandgap semiconductors having extraordinary properties such as good UV absorbent, extremely high mechanical hardness, chemical inertness, and high thermal conductivity (7–12). Because of these properties, single or multilayer TiO2 and Al2O3 films have incurred good candidature in space industries for such applications (13–14). Although there are reports showing that electron irradiation on TiO2 or Al2O3 single layer films have enhanced the film properties through densification, residual stress, defects generation etc. but less reports are available related to multilayered films (15,16). Therefore, it is technical and scientific interest to study the effects of electron beam radiation on TiO2/Al2O3 multilayer thin films. Here, we investigate how high energetic electron beam irradiation effects on optical and electrical properties of four layered rf magnetron sputter deposited TiO2/Al2O3 thin films. We believe that our findings could be important in the contest of the present efforts to select suitable coatings for optical devices in the space environment.