Session E5: GS-2: Hypervelocity Impact Response and Debris Clouds

The Recent Research Progresses in Space Debris Hypervelocity Impact Test in CAST

A more perfect projectile/sabot aerodynamic separating technique in hypervelocity impact experiment was developed. By using this technique, the Al sphere with diameters from 10 mm to 1 mm were separated with sabot 100{\%} successfully in the velocity ranges of 3$\sim $ 7km/s, on the two-stage-light-gas gun with 18 mm caliber. The technique of flier-plate with graded wave impedance in hypervelocity launcher was developed, and a titanium plate with 4mm in diameter and 2 mm in thickness was launched to 10km/s. The ballistic limit curve of typical aluminum alloy whipple shield was investigated by both experiment and numerical simulation, the results were compared with Christiansen equation, and a jump phenomena were found at velocity between 8.5km/s and 11km/s in simulation results. The hypervelocity impact damage characteristic and damage model of fused silica glass outer windshield was obtained by using the two-stage-light-gas gun up to 6.5 km/s impacting velocity. The hypervelocity impacts on the outer surfaces functional material, such as the thermal control material, window glass, and OSR etc., by using The Laser-driven Flyer system are also reviewed.   

Demonstration of Survivable Space Penetrator

This work was performed in support of MoonLITE which is a proposed UK space mission to the moon. The basic premise is to deploy 4 instrumented penetrators, one each on the near-side, far-side and at the poles of the moon, with an impact velocity of approximately 300m/s. The primary science aims are to set up a passive seismometer network, investigate the presence of water and volatiles and determine thermal gradients in the lunar soil (i.e. regolith). A key requirement is that the penetrator shell survives the impact together with the instrument payload and supporting subsystems. The material chosen for the penetrator shell was 7075 aluminum alloy, which is a good compromise between high compressive strength and low mass. The baseline penetrator design was evaluated and refined using the DYNA3D hydrocode to determine the survivability of the penetrator in sand at an impact velocity of 300m/s and an attack angle of 8 degrees. The simulations predicted that the penetrator design would survive this severe impact condition which was confirmed by experiments on the Pendine rocket test track.   

Hypervelocity sub 10-micron impacts into aluminium foil: new experimental data and implications for comet 81P/Wild-2's dust fluence

Recent experimental work (\textit{Price, M. C. et. al., LPSC XXXX, {\#}1564, 2009) }has shown that the lip-to-lip diameter of hypervelocity impact craters at micron-scales (D$_{p}<$ 10 microns) is a non-linear function of the impactor's diameter (D$_{p})$. We present data for monodisperse silica projectiles impacting aluminium-1100 and elemental aluminium at 6.1 km$\backslash $sec and discuss the implications of this effect for the Stardust fluence calibration for micron-scale particles (which make up the majority of the impactor flux). Hydrocodes have been used to investigate the potential causes of the phenomena and the results are presented.   

Numeric investigations of the sensitivity of debris cloud thermodynamic state to equation of state

Modeling of hypervelocity impact generated debris clouds with hydrocodes has been focused primarily on the cloud shape and behavior. Little attention has been paid to understanding the thermodynamic state, temperature and phase of the debris. This paper will examine such thermodynamic effects through modifications to existing analytical equations of state (EOSs) in order to demonstrate the sensitivity of debris cloud thermodynamics to changes in EOS. A companion paper (Nance, Worsham, and Cogar, ``Equation of State Effects in Hypervelocity Impact Simulations'') will focus on modeling such impacts using tabular EOSs.   

Dynamic Response of Submerged Structures to Bubble Impact Loading

This paper presents a study on dynamic response of a submerged structure to impact loading induced by an underwater explosion bubble. The structure response to the bubble impact loading is simulated by a coupled boundary element method (BEM) with finite element method (FEM). The BEM is used to simulate the physical process of the explosive bubble growth, contraction and collapse, while the FEM is used to simulate the submerged structure response to the impact loading induced by the underwater explosion bubble. The benchmark tests are conducted, showing the capability of the simulation method. The effects of different charge locations on both structural responses and bubble deformations are examined. From the results obtained, some insights to the problem of submerged structures subjected to impact loading induced by underwater explosion bubbles are deduced.   

Analysis of the vibration environment induced on spacecraft components by hypervelocity impact

This paper reports the result achieved within the study ``Spacecraft Disturbances from Hypervelocity Impact'', performed by CISAS and Thales-Alenia Space Italia under European Space Agency contract. The research project investigated the perturbations produced on spacecraft internal components as a consequence of hypervelocity impacts of micrometeoroids and orbital debris on the external walls of the vehicle. Objective of the study was: (i) to set-up a general numerical /experimental procedure to investigate the vibration induced by hypervelocity impact, (ii) to analyze the GOCE mission in order to asses whether the vibration environment induce by the impact of orbital debris and micrometeoroids could jeopardize the mission. The research project was conducted both experimentally and numerically, performing a large number of impact tests on GOCE-like structural configurations and extrapolating the experimental results via numerical simulations based on hydrocode calculations, finite element and statistical energy analysis. As a result, a database was established which correlates the impact conditions in the experimental range (0.6 to 2.3 mm projectiles at 2.5 to 5 km/s) with the shock spectra on selected locations on various types of structural models.The main out coming of the study are: (i) a wide database reporting acceleration values on a wide range of impact condition, (ii) a general numerical methodology to investigate disturbances induced by space debris and micrometeoroids on general satellite structures.