Debris/Micrometeoroid Impacts and Synergistic Effects on Spacecraft Materials

MRS Bulletin ◽  
2010 ◽  
Vol 35 (1) ◽  
pp. 41-47 ◽  
Author(s):  
E. Grossman ◽  
I. Gouzman ◽  
R. Verker

AbstractIn the last 40 years, the increased space activity created a new form of space environment of hypervelocity objects—space debris—that have no functional use. The space debris, together with naturally occurring ultrahigh velocity meteoroids, presents a significant hazard to spacecraft. Collision with space debris or meteoroids might result in disfunction of external units such as solar cells, affecting materials properties, contaminating optical devices, or destroying satellites. The collision normally results in the formation of additional debris, increasing the hazard for future missions. The hypervelocity debris effect is studied by retrieving materials from space or by using ground simulation facilities. Simulation facilities, which include the light gas gun and Laser Driven Flyer methods, are used for studying the materials degradation due to debris impact. The impact effect could be accelerated when occurring simultaneously with other space environment components, such as atomic oxygen, ultraviolet, or x-ray radiation. Understanding the degradation mechanism might help in developing materials that will withstand the increasing hazard from the space debris, allowing for longer space missions. The large increase in space debris population and the associated risk to space activity requires significant measures to mitigate this hazard. Most current efforts are being devoted to prevention of collisions by keeping track of the larger debris and avoiding formation of new debris.

Author(s):  
J. Zhao ◽  
F. Tan ◽  
C. Liu ◽  
C. Sun

The near-earth space environment is cluttered with man-made debris and naturally occurring meteoroids, which is a big menace to the safety of satellites and spacecrafts. This paper is addressed on the failure response of aluminum shields under hypervelocity impact of milligrame level flyer. A compacted electric gun is employed to accelerate a mylar flyer up to 10 km/s. Failure response of Ly12 aluminum shields with different thickness and layers impacted by mylar flyer with different velocities is under investigation. The spallation is observed in the rear free surface of 4 mm thick monolithic aluminum shield, and its fracture mechanism changes from plastic to brittle when loading pressure is above 13 GPa. A perforation with a diameter 8 mm in the impacted area of the 4mm thick Ly12 shield is observed after which is impacted by 0.1 mm thick mylar flyer 8mm in diameter with velocity 8.2 km/s. When three layers of shields are impacted, the debris clouds (DC) are observed in the first and the second spaces respectively during the impact process by high speed camera, and its leftover can be observed on the surface of the third plate. The shape of the first debris cloud head is a little flat, and its speed of lateral expansion is very slow, which is different from those impacted by spherical projectile, and its formation mechanics mainly attributes to multi-spallations based on the analysis of simulation.


2007 ◽  
Vol 348-349 ◽  
pp. 785-788 ◽  
Author(s):  
Gong Shun Guan ◽  
Bao Jun Pang ◽  
Yue Ha

Impacts of meteoroids and space debris on pressure vessels can have detrimental consequences for any mission. Depending on the parameters of the impacting particle and the characteristic of the vessel, the damages can range from relatively uncritical craters in the vessel’s surface to the catastrophic bursting of vessels, which besides the loss of vessel may result in severe secondary damages to surrounding components. In order to investigate failure mechanisms of thin-walled aluminum pressure vessels under hypervelocity impact of space debris, a non-powder two-stage light gas gun was used to launch Al-sphere projectiles impacting on unshielded and shielded vessels. Damage patterns and mechanisms leading to catastrophic rupture are discussed. Experimental results indicate that the impact kinetic energy of the projectile and the gas pressure in the vessel have an important effect on the damage modes of the vessel. On the one hand, high pressure gas can lead to a vessel blast. On the other hand, high pressure gas can mitigate the impact of the debris cloud on the rear wall of the vessel. Catastrophic rupture of unshielded gas-filled vessels can be avoided when the impact energy is less than a certain limit value. When the bumper is perforated, damage of shielded pressure vessel might be fatal for vessels with high gas pressure.


2020 ◽  
Vol 10 (9) ◽  
pp. 3011
Author(s):  
Ziying Wei ◽  
Huibo Zhang ◽  
Baoshan Zhao ◽  
Xiaoang Liu ◽  
Rui Ma

The security of the space environment is under serious threat due to the increase in space debris in orbit. The active removal of space debris could ensure the sustainable use of the space environment; this removal relies on detumbling technology. According to the characteristics of the mechanical impact-type active detumbling method, this paper discusses a method to accurately identify the impact force using a pressure sensor. In this work, the impact force between a flexible impact end-effector and the space debris was analyzed theoretically and experimentally considering the pressure change during impact. Firstly, a nonlinear impact force model was established for the impact between a flexible end-effector and space debris. Secondly, impact experiments were performed and the friction model was modified. Finally, the effect of detumbling was verified through simulation experiments. The results showed that the identification error of normal impact force was less than 6.7% and the identification error of tangential friction force was less than 6.9%. Therefore, this identification method of impact force met the requirements of space debris detumbling, which has important guiding significance for the active removal technology of space debris.


2021 ◽  
Vol 11 (20) ◽  
pp. 9490
Author(s):  
Shuyi Ren ◽  
Xiaohua Yang ◽  
Ronglan Wang ◽  
Siqing Liu ◽  
Xiaojing Sun

The wide application of satellite constellations in the field of space-based global communications and remote sensing has led to a substantial increase in small-satellite launch plans, a sharp increase in the density of space objects in low-Earth orbit (LEO), and a reduction in available orbit and frequency resources. This will further aggravate the trend of deterioration of the space debris environment. Taking the Starlink constellation as an example, this paper describes the influence of the constellation from the environmental debris flux of the satellite, the evaluation of the number of evasion maneuvers, the change of risk level, the success rate of post mission disposal (PMD) and the growth rate of space objects. The simulation results show that the collision risk of the Starlink constellation is related to the orbital parameters, and the higher success rate of post-mission disposal (PMD) can reduce the collision risk of the constellation. The large constellations increases the growth rate of space objects, and even if all the satellites are disposed of after the mission, the impact of constellations on the space environment can not be offset.


Biology ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 471
Author(s):  
Camino Gutiérrez-Corbo ◽  
Bárbara Domínguez-Asenjo ◽  
María Martínez-Valladares ◽  
Yolanda Pérez-Pertejo ◽  
Carlos García-Estrada ◽  
...  

Diseases caused by trypanosomatids (Sleeping sickness, Chagas disease, and leishmaniasis) are a serious public health concern in low-income endemic countries. These diseases are produced by single-celled parasites with a diploid genome (although aneuploidy is frequent) organized in pairs of non-condensable chromosomes. To explain the way they reproduce through the analysis of natural populations, the theory of strict clonal propagation of these microorganisms was taken as a rule at the beginning of the studies, since it partially justified their genomic stability. However, numerous experimental works provide evidence of sexual reproduction, thus explaining certain naturally occurring events that link the number of meiosis per mitosis and the frequency of mating. Recent techniques have demonstrated genetic exchange between individuals of the same species under laboratory conditions, as well as the expression of meiosis specific genes. The current debate focuses on the frequency of genomic recombination events and its impact on the natural parasite population structure. This paper reviews the results and techniques used to demonstrate the existence of sex in trypanosomatids, the inheritance of kinetoplast DNA (maxi- and minicircles), the impact of genetic exchange in these parasites, and how it can contribute to the phenotypic diversity of natural populations.


Marine Drugs ◽  
2021 ◽  
Vol 19 (4) ◽  
pp. 196
Author(s):  
Muhammad Bilal ◽  
Leonardo Vieira Nunes ◽  
Marco Thúlio Saviatto Duarte ◽  
Luiz Fernando Romanholo Ferreira ◽  
Renato Nery Soriano ◽  
...  

Naturally occurring biological entities with extractable and tunable structural and functional characteristics, along with therapeutic attributes, are of supreme interest for strengthening the twenty-first-century biomedical settings. Irrespective of ongoing technological and clinical advancement, traditional medicinal practices to address and manage inflammatory bowel disease (IBD) are inefficient and the effect of the administered therapeutic cues is limited. The reasonable immune response or invasion should also be circumvented for successful clinical translation of engineered cues as highly efficient and robust bioactive entities. In this context, research is underway worldwide, and researchers have redirected or regained their interests in valorizing the naturally occurring biological entities/resources, for example, algal biome so-called “treasure of untouched or underexploited sources”. Algal biome from the marine environment is an immense source of excellence that has also been demonstrated as a source of bioactive compounds with unique chemical, structural, and functional features. Moreover, the molecular modeling and synthesis of new drugs based on marine-derived therapeutic and biological cues can show greater efficacy and specificity for the therapeutics. Herein, an effort has been made to cover the existing literature gap on the exploitation of naturally occurring biological entities/resources to address and efficiently manage IBD. Following a brief background study, a focus was given to design characteristics, performance evaluation of engineered cues, and point-of-care IBD therapeutics of diverse bioactive compounds from the algal biome. Noteworthy potentialities of marine-derived biologically active compounds have also been spotlighted to underlying the impact role of bio-active elements with the related pathways. The current review is also focused on the applied standpoint and clinical translation of marine-derived bioactive compounds. Furthermore, a detailed overview of clinical applications and future perspectives are also given in this review.


2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Camille Merienne ◽  
Chloe Marchand ◽  
Samira Filali ◽  
Damien Salmon ◽  
Christine Pivot ◽  
...  

AbstractBackgroundStability of low amoxicillin oral dosage form (5 mg) used in reintroduction drug test was not fully documented. Furthermore, the impact of (1) salt moiety of amoxicillin and (2) amoxicillin – excipient interactions upon the antibiotic formulation stability during the storage was not characterized so that the estimation of the pharmaceutical expiration date from shelf-life was uncertain. Thus, the main goal of this study was to estimate the shelf-life of two formulations of amoxicillin, using a semi-predictive methodology.MethodsAmoxicillin sodium (AS) and amoxicillin trihydrate (ATH), corresponding to 5-mg amoxicillin, were compounded with microcrystalline cellulose (MCC) in oral hard capsules which were, then, submitted to four environmental conditions (25 °C / 60% or 80% relative humidity (RH); 40 °C / 75% RH; 60 °C / 5% RH) in climatic chambers for 45 and 84 days. Therefore, the characterization of amoxicillin-MCC mixture was assessed by attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR) The profiles of amoxicillin content (determined by stability indicating chromatographic method) as a function of storage time, temperature and RH were fitted to pre-defined kinetic models performed by accelerated predictive stability (APS).ResultsATR-FTIR analysis of AS, ATH, MCC and bulk specimens stored in heated and humid atmosphere confirmed water sorption to cellulose described by a broad and unresolved 3600 to 3000 cm−1 band associated with (1) general intramolecular and intermolecular hydrogen bonding between water and hydroxyl groups of the cellulose, and with (2) free hydroxyl in cellulose. Moreover, a dramatic decrease of absorption at 1776 and 1687 cm−1 respectively characteristic of the β-lactam ring (νC=O) and amide group (νC=O), was revealed as a consequence of AS and ATH degradation caused by moisturization of bulk. Amoxicillin degradation was established by chromatographic analysis showing faster AS degradation than ATH throughout time exposure. The combined effects of temperature – RH were successfully modeled by APS, where AS and ATH showed accelerated (auto-catalysis degradation mechanism) and linear degradation, respectively. The faster AS degradation was assumed to be linked to lower hydrogen donor to hydrogen acceptor count ratio and polar surface than ATH, increasing the probability of AS hydrolysis by water adsorption to AS-MCC solid dispersion (e.g., by reduction of protective intramolecular hydrogen bonds between AS molecules). Furthermore, the compounding which involved a drastic homogenization of solids may have affected the crystalline degree of MCC with an increase of amorphous phase more sensitive to water adsorption.ConclusionsThe improvement of amoxicillin compounding for oral dose forms might be rationalized by taking into account the molecular descriptors of salt moiety and excipients, improved by the choice of an appropriate process of production, characterized from infrared vibrational spectroscopy and chromatographic analysis and finally predicted from accelerated stability assays.


2021 ◽  
Vol 13 (9) ◽  
pp. 4606
Author(s):  
Faisal Masood ◽  
Perumal Nallagownden ◽  
Irraivan Elamvazuthi ◽  
Javed Akhter ◽  
Mohammad Azad Alam

A compound parabolic concentrator (CPC) is a non-imaging device generally used in PV, thermal, or PV/thermal hybrid systems for the concentration of solar radiation on the target surface. This paper presents the geometric design, statistical modeling, parametric analysis, and geometric optimization of a two-dimensional low concentration symmetric compound parabolic concentrator for potential use in building-integrated and rooftop photovoltaic applications. The CPC was initially designed for a concentration ratio of “2×” and an acceptance half-angle of 30°. A MATLAB code was developed in house to provoke the CPC reflector’s profile. The height, aperture width, and concentration ratios were computed for different acceptance half-angles and receiver widths. The interdependence of optical concentration ratio and acceptance half-angle was demonstrated for a wide span of acceptance half-angles. The impact of the truncation ratio on the geometric parameters was investigated to identify the optimum truncation position. The profile of truncated CPC for different truncation positions was compared with full CPC. A detailed statistical analysis was performed to analyze the synergistic effects of independent design parameters on the responses using the response surface modeling approach. A set of optimized design parameters was obtained by establishing specified optimization criteria. A 50% truncated CPC with an acceptance half-angle of 21.58° and receiver width of 193.98 mm resulted in optimum geometric dimensions.


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