Hypervelocity impact simulation experiments on LDEF°-foils

A variety of space environmental effects can be studied on many experiments having been exposed on the LDEF-satellite.

Among others the thermal blankets of the Ultra-Heavy Cosmic Ray Nuclei Experiment (“UHCRE”, Exp. A0178) displayed many micrometeoroid / space debris impact features.

In an effort to understand their nature and characteristics, an experimental impact simulation program has been carried out.

UHCRE-spare foils have been impacted by glass, aluminium, and iron projectiles with masses ranging from about 30 nanograms up to several milligrams. Impact velocities range between about 3 km/s and 13 km/s.

Characteristic impact craters and perforation holes have been produced. Their sizes and morphologies have been related with respective projectile impact parameters.

“Halo zones” around perforation holes, as they had been observed in the exposed LDEF-foils, have also been obtained experimentally. They were found to be delamination effects within the foil layers caused by the propagation of impact shock waves.     

Accelerator test of an angle detecting inclined sensor (ADIS) prototype with beams of Ca and fragments

The measurement of cosmic rays and Solar energetic particles in space is basic to our understanding of the Galaxy, the Sun, phenomena in the Heliosphere and what has come to be known broadly as “space weather”. For these reasons, cosmic ray instruments are common on both scientific spacecraft and operational spacecraft such as weather satellites.

The resource constraints on spacecraft generally mean that instruments that measure cosmic rays and Solar energetic particles must have low mass (a few kg) and low power (a few W), be robust and reliable yet still highly capable. Such instruments must identify ionic species (at least by element, preferably by isotope) from protons through the iron group. The charge and mass resolution of heavy ion instruments in space depends upon determining ions’ angles of incidence. The Angle Detecting Inclined Sensor (ADIS) system is a highly innovative and uniquely simple detector configuration used to determine the angle of incidence of heavy ions in space instruments. ADIS replaces complex position sensing detectors (PSDs) with a system of simple, reliable and robust Si detectors inclined at an angle to the instrument axis.

In August 2004, we tested ADIS prototypes with a ⁴⁸Ca beam at the National Superconducting Cyclotron Laboratory's (NSCL) Coupled Cyclotron Facility (CCF). Among the analyses performed on the data taken at the NSCL, we demonstrate that our prototype design with an ADIS system has a charge resolution of less than 0.25e. We also present a more generalized analytic derivation of instrument response and report on the corresponding analysis of Monte-Carlo modeling data.     

A comparison of fragmentation models

The key to conducting an accurate lethality assessment is the use of a robust assessment methodology. One of the critical components of a lethality assessment is the characterization of the debris cloud created by the initial high speed impact. Without a proper characterization, it is impossible to obtain an accurate prediction of the response of an interior target component to subsequent debris cloud impact loadings. The fast-running codes FATEPEN2, KAPP-II, and PEN4 contain fragmentation models that characterize the debris cloud fragment population resulting from a high speed impact. The objective of the work described in this paper as to compare the predictions of the fragmentation models within these three codes over the 1–16 km/s impact velocity regime. This objective was achieved through a parametric study of debris cloud material characterization using the fragmentation schemes in the FATEPEN2, KAPP-II, and PEN4 semi-empirical lethality assessment schemes for a variety of projectile and target materials and configurations.     

The chemistry of micrometeoroid and space debris remnants captured on hubble space telescope solar cells

Prior to the retrieval in 1993 from low Earth orbit (LEO), the “—V2” Solar Array wing of the Hubble Space Telescope was exposed to hypervelocity impacts (micrometre to millimetre scale) from both micrometeoroids and space debris. The initial survey of the damage (100–3500μm diameter sized craters) identified that micrometeoroid remnants dominated the flux in the 100–1000μm size regime, with debris dominating>1000μm. These residues were composed of remnants of silicate minerals, calcite, metal sulfides and metals that often appeared as complex poly-mineralic melts within melt pits. A further survey of 10–100μm diameter craters identified that the most common chemistry was space debris with the crossover from meteoroids to debris being at around 30μm D_CO. Residues include remnants of specialised steels and paint fragments but the dominant type is aluminium and aluminium oxide, which are almost certainly remnants of solid rocket motor operations. It is found that the relative contribution of debris as a function of size, agrees remarkably with a prediction derived using flux data from Long Duration Exposure Facility and a meteoroid model.     

The effect of thin deployable construction elements of the international space station on the probability of its hull penetration by meteoroids and orbital debris

When calculating the probability of hull penetration by meteoroid and orbital debris (M/OD) for some of the International Space Station (ISS) modules (e.g. FGB, Service module, cargo vehicle “Progress”), one has to take into account their additional shielding produced by ISS deployable construction elements (such as solar panels, radiators), which decrease M/OD penetrating probabilities. The lack of developed calculation methods of accounting for this effect has arisen the necessity to investigate the law— governed nature of particle fragmentation process accompanying high velocity penetration of thin barriers, as well as to elaborate techniques for correct calculation of the probability of no penetration (PNP) of module pressure wall. The results of thorough analysis of the theoretical and experime ntal published data as well as of data obtained in joint NASA and RSA experimental program on particle fragmentation are presented in this report in the form of normalized analytical correlation between the fragment maximum size and impact parameters. On the basis of above mentioned particle fragmentation law, the method of module hull ballistic limit curves (BLC's) recalculation is determined, which include the effect of thin barriers greatly distanced from the module hull. This BLC's are used for module PNP calculations with the help of modified version of NASA BUMPER code. The special subroutines accounting for PNP changes due to the particle collisions with ISS deployable construction elements are introduced in the BUMPER algorithm. The results of the Service module PNP calculations with account for its “shadowing” by solar panels and radiators are presented.     

Effect of Particle Size on Deformation and Compaction Characteristics of Ascorbic acid and Potassium Chloride: Neat and Granulated Drug

Deformation and compaction characteristics of two soluble drugs, ascorbic acid and potassium chloride, were investigated. Five different particle size fractions of ascorbic acid with mean particle size (d₅₀) ranging from 30-300μm and four different particle size fractions of potassium chloride with d₅₀ ranging from 20-400 μm were selected in the study. The compaction behavior of the drug substances as neat drugs or as granulated drugs were evaluated on both a Carver press and an instrumented single-punch tablet press. The results clearly show that mean particle size of the drug substances plays an important role in their compactibility. Intrinsic compactibility of both drug substances was slightly improved with increased particle size. Granulations of the drugs with polyvinyl pyrrolidone significantly improved their compactibility. However, this effect was more pronounced in the drug substance with finer particle size. The Heckel plots indicate that deformation characteristics of both granulated drugs were related to their original mean particle sizes. The granulations prepared from the coarser particle size (d₅₀ 250 μm to 400 μm) underwent two stages of deformation, so-called “brittle fracture” and “plastic deformation”. While the granulations prepared from the finer particle size predoninantly underwent “plastic deformation”. The results indicated that the plastic deformation of both granulated drugs was progressively enhanced whilst fragmentation of particles was correspondingly reduced as the particle size of the drugs was decreased. Scanning electron photomicrographs indicated that the granulation process changed the surface morphology of the drug particles imparting more “microirregularities” or “defects”, thereby providing greater “interparticulate bonding” as compared with the neat drugs. Optimum particle size range of ascorbic acid and potassium chloride for satisfactory compactibility was found to be 30-40 μm and 20-40 μm, respectively. The present study demonstrates the importance of selecting the appropriate particle size of drug for the development of tablet dosage forms.     

Degradation and destruction of optical surfaces by hypervelocity impact

This study investigates the damage caused by impacts of space debris and micrometeoroids (SD/MM) on mirrors of placed on spacecrafts in an orbit of 700 km and 1400 km altitude with an inclination of 48°. For the investigated orbits the maximum damage from impact degradation of the optical surface as well as the probability of total destruction by single particle hit has been calculated. Based on the NASA statistical standard model ORDEM 96, the calculation of SD particle fluxes shows that at 700 km altitude an average of 62000 impact damages per m² and per year are caused by particles with a diameter equal or larger than 1 μm. At 1400 km altitude the figure is reduced by 30%. The corresponding MM fluxes have been calculated with the Grün model and are 1.5 orders of magnitude smaller than the SD fluxes. For the generation of a damage law and for the determination of the total destruction limits, 50 impact damages were produced on coated and uncoated quartz glass samples, employing the impact facilities of the Ernst-Mach-Institute (EMI) and the Aerospace Department of the Technical University Munich (TUM/LRT). The particle sizes were varied between 3 μm and 1000 μm. The impact velocities were between 2.0 km/s and 16.1 km/s. Due to the irregular damages a clear correlation with the impact angle (0°, 30°, 60°) could not be proven. The diameter of the optically inactive surface after impact is proportional to E^0.458 (where E = kinetic energy of the impact). The experimental total destruction limit of 5 mm thick quartz glasses is reached with an impact energy of 13.5 J (Aluminum sphere, 0.9 mm diameter, 5 km/s impact velocity). The degradation analysis showed that 3.5 % of the optical surfaces of the mirrors in 700 km orbits (48 ° inclination) is destroyed within 10 years by space debris and micro-meteoroids. The probability of total destruction for the considered mirrors in 700 km altitude is in the percent range for an operational period of 10 years. Degradation damages and the probability of total destruction in an orbit in 1400 km is slightly below the values for the 700 km orbit.     

The treasure of gold and silver artifacts from the Royal Tombs of Sipán, Peru — a study on the Moche metalworking techniques

In 1987–1990, a spectacular treasure of gold and silver ornamental and ceremonial artifacts was recovered scientifically from the unlooted Royal Tombs of Sipán, Peru (dated to approximately AD 50–300). These objects give evidence of the outstanding craftsmanship of the Moche metalsmiths and reflect the various elaborate metalworking techniques available at that time. The present paper summarizes the results of a study on an array of artifacts stemming mainly from the tomb of the “Lord of Sipán.” Most of the objects were found to be made of thin sheet metal (1–<0.1 mm thick), which was further worked by cutting, embossing, punching, and chasing. Three-dimensional structures were created from pieces of the sheet metal by mechanical or metallurgical joining (soldering or welding). The Moche metalsmiths were masters in making objects that looked like pure gold or silver. In the case of copper objects, the surfaces were often found to be gilded electrochemically by the deposition of very thin gold films. In the case of objects made of alloys of copper with gold and some silver (tumbaga) or of copper with silver, the surface gilding or silvering was achieved by the depletion of copper, mostly by selectively oxidizing the surface copper and etching away the copper oxides that are formed.     

Addition of “Living” Polymers onto C60.

Various “living” polymers were grafted onto C₆₀ The number of arms of the so obtained “star” molecules can be controlled by stoechiometry and/or by varying the reactivity of the carbanion on the “living” chain against a double bond on the C₆₀. Even the oxanion of “living” polyethylenoxide is able to add onto the reactive double bonds on C₆₀. In some conditions, the carbanions present on these alkaline salts of grafted fullerenes becomes able to initiate anionic polymerization of vinyl monomers. Using “living” poly(phenylvinylsulfoxide) as a precursor polymer for PA, polyacetylene chains could be attached to the fullerene.     

Fracture of solids by radiation pulses as a method of ensuring safety in space

To determine the optimum conditions of fracturing or altering the trajectory of dangerous space objects (large iron or rock space bodies, threatening to collide with the Earth), and also destroy space debris in the space around the Earth, the author presents a mathematical formulation of the problem of calculating the dynamic strength of solids under the effect of high-energy loading pulses. The results of numerical modeling are compared with the experimental data for the formulation of cupola-shaped swollen areas on the rear surface of a metallic plate subjected to laser radiation. The change in the fracture mechanisms (front and rear spallation) with increasing energy of the effect has been detected. Recommendations are given for optimizing the pulsed laser effect on dangerous space objects to ensure the fragmentation or change their orbit.Expanded form of the document presented at the International Conference Space Protection of the Earth≓ (SPE'94, Snezhinsk, Russian, September 26–30, 1994).Translated from Problemy Prochnosti, No. 3, pp. 31–51, March, 1996.     

Characterization of prompt flash signatures using high-speed broadband diode detectors

Impact flash is a brief, intense flash of light released when a target is impacted by a hypervelocity particle. It is caused by emissions from a jet of shocked material which is thrown from the impact site. Impact flash phenomenology has been known for decades, and is now being considered for applications where remote diagnostics are required to observe and diagnose impacts on satellites and space craft where micrometeoroid and orbital debris impacts are common. Additionally, this phenomena and remote diagnostics are under consideration for missile defense applications. Currently, optical signatures created from hypervelocity impact can be utilized as the basis for detectors (spectrometers, pyrometers), which characterize the material composition and temperature. More recent interest has focused on study of hypervelocity impact generated debris and the physics of the associated rapidly expanding and cooling multiphase debris cloud. To establish this capability technically in the laboratory, we have conducted a series of experiments on a two-stage light gas gun at impact velocities ranging from 6 to 19 km/s, which is representative for light emissions resulting from hypervelocity impacts in space. At these high impact velocities jetting is no longer the dominant mechanism for observed impact flash signatures. The focus of this work is to develop fast, inexpensive photo-diodes for use as a reliable prompt flash, and late time radiating debris cloud diagnostic to: (a) characterize material behavior in the shocked and expanding state when feasible; (b) ascertain scaling of luminosity with impact velocity; (c) determine the temperature of the impact flash resulting from radiating emissions when multiple silicon diodes are used in conjunction with narrow band pass filtering at specific wavelengths as a pyrometer. The results of these experiments are discussed in detail using both a metallic target, such as aluminum, and an organic material such as Composition-B explosive.     

The impact of flat, thin plates on aluminum targets in the 5–10 km/s velocity range

The purpose of the study was to investigate the effect of the impact of a thin membrane on aluminum in the velocity range 6–10 km/s. The impulsive load delivered by a membrane impact will exceed the momentum/area of the membrane because of rebound, blow-off of vaporized membrane material, and ejection of molten and fractured material from the target (impulse gain). One of the objectives of the study was to quantify the impulse gain in the velocity range of interest. Also of interest was the physical damage to the target including spall, melting and fracture. Understanding these damage mechanisms is important for protecting spacecraft from the impact of space debris and meteoroids.

Simple theories account for the flyer rebound, but hydrodynamic modeling is required to treat the blow-off of target material. At lower velocities, the blow-off is negligible, but at10 km/s calculations show it to be equal to the rebound momentum for one-dimensional (1-D) impacts. The modeling of three-dimensional (3-D) experiments revealed large effects at the edge of an impacting membrane, prompting an emphasis on 1-D pressure profile experiments.     

Aspects of reliability design of hydrocarbon offshore platforms

The paper is a critical examination of Reliability and Safety aspects relating to Offshore Hydrocarbon Platforms. It aims at providing appropriate Design Criteria and proposing reasons for the implementation of more qualified gas detection systems technologies. Criteria generally adopted for manned platforms, associating an alarm to the detection of gas, cannot be extrapolated to unmanned platforms, especially when the topside is not realised on the basis of a completely ‘open’ layout.

The paper discusses reliability design criteria for manned platformsbased on operational design experience and discusses design improvements and reasons for the greater reliability required from gas detection systems when applied to unmanned platforms.     

Global systems in the post-cold war information age : Chips, orbits, and new stimuli for cooperation

The US space program is held back by the high cost and inflexibility of access to space using current launch systems. But as a result of impressive advances in hypersonic aeronautics and advanced materials in recent years, there are excellent prospects for developing a fully reusable air-breathing single-stage-to-orbit launch vehicle during the next decade. The National Aerospace Plane (NASP) is a US technology development program that could lead to immense reductions in low-earth orbit launch costs and provide the operational flexibility of aircraft-like operations. Such a capability would cause a broad rethinking of the “market” for space launch, leading to introduction of new services and uses of space, particularly those taking advantage of the capabilities of small satellites.     

From Columbia to Discovery: Understanding the impact threat to the space shuttle

The loss of the space shuttle Columbia in 2003 was caused by the impact of foam insulation on the leading edge of the wing. The foam strike created a hole in reinforced carbon–carbon panel 8 that led to excessive heating during re-entry, loss of the integrity of the left wing, and subsequent loss of the vehicle and crew. In the 2.5 years following the accident, there was a concerted effort to understand the impact threat to the space shuttle system. The effort was a large one, and was comprised of five integrated parts: (1) identifying the debris that can be shed by the External Tank and Solid Rocket Boosters; (2) determining the impact speeds and angles that debris can strike the Orbiter; (3) quantifying the amount of damage to the thermal protection system caused by those strikes; (4) estimating the temperature rise in the damaged regions during re-entry; and (5) deciding whether the temperature rise is sufficient to affect structural integrity. Each of these parts was addressed through experimentation and the development of what are called within the space shuttle program Critical Math Models. These models are extensively verified and validated to give high confidence in their results and are baselined by the shuttle program. This paper overviews the extensive experimental and modeling efforts of the return-to-flight program, emphasizing the impact testing and modeling.     

椭球弹丸超高速撞击防护屏碎片云数值模拟

低地球轨道的各类航天器易受到微流星体及空间碎片的超高速撞击.本文采用AUTODYN软件进行了椭球弹丸超高速正撞击及斜撞击防护屏碎片云的数值模拟.给出了三维模拟的结果.研究了在相同质量的条件下,不同长径比椭球弹丸以不同速度和入射角撞击防护屏所产生碎片云的特性,并与球形弹丸撞击所应产生的碎片云特性进行了比较.结果表明:在相同的速度下,不同长径比椭球弹丸撞击的碎片云形状、质量分布和破碎程度是不同的,随撞击入射角的增加弹丸的破碎程度增大,滑弹碎片云的数量增加;随撞击速度的增加,弹丸的破碎程度也增加.     

Predicting orbital debris shape and orientation effects on spacecraft shield ballistic limits based on characteristic length

We propose the use of “characteristic length,” based on radar cross section, as a metric for comparing the performance of orbital debris impactors of differing shapes, and the use of NASA's standard breakup model (SBM) “flake” shape as the representative particle for predicting orbital debris penetration effects. We also propose the use of a 26-view methodology for examining non-spherical particles such as cylinders, rectangular prisms, octahedrons, etc., with the intent to describe their potential impact orientations while minimizing the number of hydrocode runs needed to develop orientation-dependent ballistic limit curves. Using this methodology and the smooth particle hydrodynamic code (SPHC), we predict the ballistic limit for SBM-based particles against a typical spacecraft dual-wall shield at normal obliquity and velocities of 7, 8, and 12 km/s. Finally, we compare these results with ballistic limits produced by spherical impactors of the same characteristic length as the SBM-based particles.     

A multi-shock concept for spacecraft shielding

The results of an advanced spacecraft shielding program conducted at the NASA Johnson Space Center Hypervelocity Impact Research Laboratory (HIRL) are presented. The results include two new aspects of shielding design: the geometrical configuration and the type of material used for the shield. The geometrical configuration of the shield will be the prime focus of this paper due to its application over a large range of materials. The uniqueness of this concept is in the utilization of a multi-shock (MS) shielding technique where ultra-thin (t_s) spaced (ΔS), shield elements are used to repeatedly shock the impacting projectile (diameter d_p) to a high enough energy state to cause melting and vaporization at velocities which normally would not produce these results. Although the concept of multi-sheet shields has been proposed and tested many times (Christiansen, 1987; Gehring, 1970; Rajendra and Elfer, 1989; Richardson, 1970), the t_s/d_p ratio has always been large enough that the shield material has provided a large percentage of the debris plume mass which the back sheet must withstand. This concept does not produce the same results. The low t_s/d_p adds very little shield material to the debris plume allowing a substantial decrease in the thickness (strength) of the backsheet and the proper spacing between sheets prevents the debris plume from destroying successive sheets prior to the particulates reaching the sheet. The present concept, using aluminum as an analog for comparison to a dual sheet (aluminum) “Whipple shield” results in a 30% reduction in weight.

The use of other materials with this concept can result in even greater weight savings. The concept was tested at normal impact, oblique impact, and low velocity impact (2.7 km/s) and performed as well as an equivalent dual sheet shield. The scaling characteristics of the new cincept were tested and verified for impacting projectiles of mass 45 milligrams and 1.27 grams at velocities of 6.7 km/s. The new concept provides a shield which can be tailored to meet many design requirements, produce minimal secondary debris particles, provide a means for designing an augmentable shielding system, and most important reduce the weight of debris shielding.     

Design and Computation of Fullerene C60with a Corona for Polymer Synthesis

“Saturnized fullerene C₆₀ molecules” were designed as the cardinal points for cross-linked polymers. Results from the graphic molecular modeling, including the CVFF calculations, indicate that the 1, 2-adduct [-N(CH₂)6-]6·C_6oH₆with S₆ symmetry is the best target molecule.     

航天照相侦察卫星

现代国际公约规定，一国的领空限制在80—110千米以下，在此以上像公海一样属于公空，可以自由飞行，因此容许别国飞行物，包括人造卫星，进行各种正常活动，如：探测，照相等等。航天侦察卫星就此应运而生。航天照相侦察卫星是发展最快，最成功的一类，卫星上一般安装有航天照相机或电视摄影机，对目标进行拍摄，其飞行轨道的近地点通常离地面150—280千米，所配备的摄影系统有极高的分辨率，能进行红外和多谱段拍摄，具有夜间侦察和识别伪装物的能力，集中了一些最先进的科学技术，已经取得了极佳的效果。本文对其最新的进展进行综述。