摘要 :
As time progresses, space becomes more congested with micrometeoroids and orbital debris (MMOD). This increase in debris flux poses a critical threat to satellites already in orbit, manned missions, and future orbiting spacecraft....
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As time progresses, space becomes more congested with micrometeoroids and orbital debris (MMOD). This increase in debris flux poses a critical threat to satellites already in orbit, manned missions, and future orbiting spacecraft. To reduce the operational impact of MMOD collisions, current protection schemes use Whipple Shields, an aluminum plate with a prescribed standoff distance, as the basis for protection. These aluminum shields are manufactured and installed on the space vehicle while on Earth, which constrains their size and shape, and ultimately, their effectiveness. These fixed shields also cannot be repaired if they are damaged during service. This work describes a prototype shield system that can be additively manufactured and installed while the vehicle is in orbit. This system, designed for manufacture via three-dimensional printing in space, would allow an operator to add shielding to a vehicle once in orbit, protecting it against MMOD traveling at hyper velocities. These on-orbit manufactured shields allow specific tailoring to more-efficiently and effectively meet mission requirements. CTH finite element code was used to simulate hypervelocity impacts (HVI) on computer-aided design (CAD) models of the prototypes. These simulations used structures made of analogous materials such as polycarbonate to make and evaluate new design parameters. The performance of different design parameters in simulations drove a redesign of the original prototype. These new designs were additively manufactured with ULTEM 9085, and underwent testing at a hypervelocity impact laboratory. Six prototypes were tested and successfully survived a hypervelocity projectile impact, indicating their potential effectiveness as spacecraft MMOD shielding.
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摘要 :
As time progresses, space becomes more congested with micrometeoroids and orbital debris (MMOD). This increase in debris flux poses a critical threat to satellites already in orbit, manned missions, and future orbiting spacecraft....
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As time progresses, space becomes more congested with micrometeoroids and orbital debris (MMOD). This increase in debris flux poses a critical threat to satellites already in orbit, manned missions, and future orbiting spacecraft. To reduce the operational impact of MMOD collisions, current protection schemes use Whipple Shields, an aluminum plate with a prescribed standoff distance, as the basis for protection. These aluminum shields are manufactured and installed on the space vehicle while on Earth, which constrains their size and shape, and ultimately, their effectiveness. These fixed shields also cannot be repaired if they are damaged during service. This work describes a prototype shield system that can be additively manufactured and installed while the vehicle is in orbit. This system, designed for manufacture via three-dimensional printing in space, would allow an operator to add shielding to a vehicle once in orbit, protecting it against MMOD traveling at hyper velocities. These on-orbit manufactured shields allow specific tailoring to more-efficiently and effectively meet mission requirements. CTH finite element code was used to simulate hypervelocity impacts (HVI) on computer-aided design (CAD) models of the prototypes. These simulations used structures made of analogous materials such as polycarbonate to make and evaluate new design parameters. The performance of different design parameters in simulations drove a redesign of the original prototype. These new designs were additively manufactured with ULTEM 9085, and underwent testing at a hypervelocity impact laboratory. Six prototypes were tested and successfully survived a hypervelocity projectile impact, indicating their potential effectiveness as spacecraft MMOD shielding.
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摘要 :
As time progresses, space becomes more congested with micrometeoroids and orbital debris (MMOD). This increase in debris flux poses a critical threat to satellites already in orbit, manned missions, and future orbiting spacecraft....
展开
As time progresses, space becomes more congested with micrometeoroids and orbital debris (MMOD). This increase in debris flux poses a critical threat to satellites already in orbit, manned missions, and future orbiting spacecraft. To reduce the operational impact of MMOD collisions, current protection schemes use Whipple Shields, an aluminum plate with a prescribed standoff distance, as the basis for protection. These aluminum shields are manufactured and installed on the space vehicle while on Earth, which constrains their size and shape, and ultimately, their effectiveness. These fixed shields also cannot be repaired if they are damaged during service. This work describes a prototype shield system that can be additively manufactured and installed while the vehicle is in orbit. This system, designed for manufacture via three-dimensional printing in space, would allow an operator to add shielding to a vehicle once in orbit, protecting it against MMOD traveling at hyper velocities. These on-orbit manufactured shields allow specific tailoring to more-efficiently and effectively meet mission requirements. CTH finite element code was used to simulate hypervelocity impacts (HVI) on computer-aided design (CAD) models of the prototypes. These simulations used structures made of analogous materials such as polycarbonate to make and evaluate new design parameters. The performance of different design parameters in simulations drove a redesign of the original prototype. These new designs were additively manufactured with ULTEM 9085, and underwent testing at a hypervelocity impact laboratory. Six prototypes were tested and successfully survived a hypervelocity projectile impact, indicating their potential effectiveness as spacecraft MMOD shielding.
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摘要 :
Spacecraft operating in low-Earth orbit (LEO) are subjected to a number of hazardous environmental constituents that can lead to decreased system performance and reduced operational lifetimes. Due to their thermal, optical, and me...
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Spacecraft operating in low-Earth orbit (LEO) are subjected to a number of hazardous environmental constituents that can lead to decreased system performance and reduced operational lifetimes. Due to their thermal, optical, and mechanical properties, polymers are used extensively in space systems; however they are particularly susceptible to material erosion and degradation as a result of exposure to the LEO environment. The focus of this research is to examine the material erosion and mass loss experienced by the Novastrat 500 polyimide due to exposure in a simulated LEO environment. In addition to the polymer samples, chrome, silver and gold specimens will be examined to measure the oxidation rate and act as a control specimen, respectively. A magnetically filtered atomic oxygen plasma source has previously been developed and characterized for the purpose of simulating the low-Earth orbit environment. The plasma source can be operated at a variety of discharge currents and gas flow rates, of which the plasma parameters downstream of the source are dependent. The characteristics of the generated plasma were examined as a function of these operating parameters to optimize the production of O~+ ions with energy relevant to LEO applications, where the ram energy of the ions due to the motion of the satellite relative to the LEO plasma is high (e.g. 7800 m/s, which corresponds to approximately 5 eV of kinetic energy for O~+ ions). The plasma downstream of the source consists of streaming ions with energy of approximately 5 eV and an ion species fraction that is approximately 90% O~+.
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