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Space Situational Awareness & Space Traffic Management
Published in M. Madi, O. Sokolova, Space Debris Peril: Pathways to Opportunities, 2020
Space operators have a wealth of authoritative information that they may be willing to share with others in the interest of space safety. The upper left box in Fig. 2.11 depicts data from contributing space operators, whether they be operating satellites, launch booster and upper-stage vehicles, sub-orbital/exoatmospheric vehicles (e.g. space tourism), high-altitude balloons, or airships. Operator space platforms may host sensors and systems that can provide valuable in-situ measurements of orbital debris, spacecraft charging, and space weather proxies to aid the development and tuning of refined orbital debris models, space weather predictions and models, and dynamically calibrated atmosphere models. In this construct, contributing operators are encouraged to report any satellite and launch vehicle anomalies [12] they experience in the interests of a shared understanding of space risk.
Reliability and Flight Qualification
Published in Hamid Hemmati, Near-Earth Laser Communications, 2018
The technology of space qualification of optoelectronics and photonics components and subsystems appropriate for space-based optical communication is still developing and is defined by implementers of flight projects.Appropriate flight qualified components generally are not commercially available.Qualification of COTS is at a lower cost but higher risk approach.Qualification from the source is at a lower risk but typically higher cost approach.To quantify a subsystem’s performance under the flight qualification environment, a fairly accurate knowledge of the environmental conditions during and after launch is required for thermal, vibration, vacuum, outgassing, radiation, etc.Some reliability and qualification issues may be mitigated via modeling, while others would require verification through testing.Development of a systematic qualification approach is critical to the reliability of a given part or subsystem.Quantities in tens or even hundreds of a given part may be necessary for qualification, often from multiple vendors, to quantify a given part with low qualification heritage.Semiconductor lasers and photodetectors are sensitive to displacement damage due to protons and neutrons. Passive optical elements and fibers are sensitive to ionizing radiation, such as those caused by electrons, gamma rays, and protons.Derated operation of active elements (e.g., diode laser’s operational current) improves reliability of the device.Heritage may be applied only to the part that is exactly the same as that flown in space.Avoid gold–indium contact in active components. Understand single event upset behavior and causes in photodetectors and laser diodes.Analyze possible pathways for spacecraft charging.Selection of Telcordia-qualified components is a good staring point in the qualification process.COTS devices may require special qualification testing—in particular, plastic parts.
Discharge and electromagnetic radiation behind the hole of simulated charging satellite surface under impact
Published in Waves in Random and Complex Media, 2022
Enling Tang, Liangliang Zhao, Yafei Han, Chuang Chen, Mengzhou Chang
Earlier studies of MMOD impact-induced EMPs and RF radiation ignored the charging conditions on the spacecraft surface. NASA has produced a graphic of spacecraft charging conditions showing that the spacecraft surface can reach more than –20,000 V under extreme conditions [28]. So it cannot ignore the coupling effect of the physical processes of hypervelocity impact and biases. Collette et al. describe laboratory experiments which reproduce characteristic signals observed on spacecraft; the results show that the positive and negative values of spacecraft surface biases will affect the signal detected by the antenna [29]. Vaverka et al. present the numerical simulations of spacecraft charging focused on changes in the spacecraft potential generated by dust impacts in various locations of the Earth’s magnetosphere [30]. To understand the microparticle hypervelocity impact plasma and its associated threat to spacecraft electronics, Hew et al. studied the hypervelocity impact flash expansion geometry under various surface electrical conditions. They concluded that impact flash cone angle depends on the impact surface electrical bias. Nuttall systematically studied the RF radiation generated by hypervelocity impact on charged targets using patch antennas, the target material was biased via an external power supply in the range of −1000–1000 V including grounded and floating configurations. In these experiments, author observe for the first time wide-band RF emissions from hypervelocity impacts with charged surfaces [31].
Development of Object-oriented PIC Code for Simulation of Plasma Flow Around a Satellite in Solar Corona
Published in International Journal of Computational Fluid Dynamics, 2021
Jorge Alberto García Pérez, Kojiro Suzuki
Since the onset of the Space Race, scientific research has been conducted on the topic of the interaction between space plasma and the surface of satellites. Between 1956 and 1957 several calculations of spacecraft charging for a satellite orbiting the Earth were published. These included phenomena such as photoemission and the effect of the relative velocity of the satellite (Whipple 1981). In the following decades, numerical simulations gained popularity within the plasma physics community in both their fluid-based and kinetic-based approaches, giving rise to codes such as NASCAP (Mandell, Stannard, and Katz 1993) or PicUp3D/SPIS (Forest, Eliasson, and Hilgers 2001). They allowed a more detailed study of phenomena such as potential barriers, wake effects and the emission of particles from the surface of the satellite.
Electrical characteristics of etched ion-tracks in polyimide filled with silver nanoparticles
Published in Radiation Effects and Defects in Solids, 2018
Tejashree Bhave, P. S. Alegaonkar, V. N. Bhoraskar, K. A. Bogle, D. K. Avasthi, S. V. Bhoraskar
Another possible reason of asymmetric current–voltage characteristic might be related to the presence of asymmetric electrostatic potential distribution across the filled tracks. This may be expected to arise from the asymmetric accumulation of trapped charges, in the metal–polymer composite, during the process of electron irradiation. In fact, charging of polymers by ionizing radiations, like electrons and gamma rays, is not new. There are many reports (22, 23) about charge accumulation in highly insulating polymers which include fluoropolymers and polyimides (24). In fact this is the main cause of the spacecraft charging leading to the so-called electrostatic discharging (ESD) (25). The extent of charge depends on the energy and intensity of radiation as well as on the nature of polymer. During electron irradiation the trapping sites are created as well as filled by electrons and may be energetically deep or shallow. Deep traps can generate bulk charges which are not affected by external environmental conditions. In the present experiment, since the two ends of the cones of the composite material, in the track, have different diameters they will have different extent of charges. This may create an asymmetric internal electrostatic potential and consequently generate an asymmetric I–V characteristic. Such an effect has also been experimentally demonstrated, in literature, by controlling the charge; either chemically or physically (26). Moreover, Kosinska (27) had proposed a theoretical model in his article ‘How the asymmetry of internal potential influences the shape of I–V characteristic of nano-channels’. The model considers the symmetric nano-pore with asymmetric charge distribution. In this model, the current rectification in asymmetrically charged nano-channels shows a diode like shape of I–V characteristic. Here it is shown that ion rectification may be induced by the coupling between the degree of asymmetry and the depth of internal electric potential well. It is stated that: although factors such as geometry, chemical structure, etc, may also be sources of the potential asymmetry, the main source of the asymmetry is the electrostatic potential. In most of these cited examples, ionic conductivity was measured in wet electrolytic medium. However, in the present experiments, influence of such potential asymmetry on the electron current in a dry system should not be much different in causing current rectification.