Recovery Capsule Research Articles

Preparation of Niobium Aluminium Alloy Based on Shock Compression Method

A new method based on a light-gas gun has been proposed to synthesize Nb-Al alloys, and a recovery capsule has been investigated. The copper-coated sample is accessible after shock wave loading. In this paper, we successfully synthesize Nb-Al alloys, which are high-temperature structural materials. X-ray diffraction is employed to clarify the structural characteristics of compounds after impact, and the simulation of X-ray diffractions is employed to clarify the structure. In detail, tetragonal NbAl3 alloys certainly appeared in the recovery capsule; this alloy is considered to be best candidate.

Design and application of new recovery capsule

Design and application of new recovery capsule

The role of decompression and micro-jetting in shock wave synthesis experiments

In a set of shock experiments under comparable porosities at pressures of about 35 GPa the melting behavior of porous copper was investigated. All experiments were performed with the impedance corrected sample recovery system and different degrees of decompression were used. It was possible to reduce the degree of molten metal in parts of the sample after sample recovery down to zero. The avoiding of melting was possible only by avoiding larger degrees of adiabatic decompression. This behavior implies a complete dependence of the melting on the release path for porous copper under the given conditions. The zones, where the melting processes are avoided, include also areas with intense micro jetting. Because also in these zones melting does not occur, it is possible that the melting curve of copper along the Hugoniot is not yet solved. The experiments have verified, that it is possible to use equation-of-state calculations for the solid state only, concerning the pressure area of currently commercial interest for the production of nitrides and diamond with copper-powder as pressure medium. Furthermore in this work the role of different parts of the sample recovery capsule is described to improve the comparability of shock wave synthesis experiments. On the other hand, the experimentally results given in this work show significant differences to data, obtained by a number of simulations.

Numerical simulation of some problems of recovery capsule aerodynamics

This paper presents the numerical simulation of the circumfluence of a recovery apparatus with brake engines and a detachable heat protection shield carried out by the use of the conservative numerical method of cluster architecture. The simulation results of the action of reactive jets of brake engines on the landing surface and the recovery apparatus, as well as the basic aerodynamic characteristics, are considered.

Aero-thermo-dynamic analysis of a low ballistic coefficient deployable capsule in Earth re-entry

The paper deals with a microsatellite and the related deployable recovery capsule. The aero-brake is folded at launch and deployed in space and is able to perform a de-orbiting controlled re-entry. This kind of capsule, with a flexible, high temperature resistant fabric, thanks to its lightness and modulating capability, can be an alternative to the current “conventional” recovery capsules. The present authors already analyzed the trajectory and the aerodynamic behavior of low ballistic coefficient capsules during Earth re-entry and Mars entry. In previous studies, aerodynamic longitudinal stability analysis and evaluation of thermal and aerodynamic loads for a possible suborbital re-entry demonstrator were carried out in both continuum and rarefied regimes. The present study is aimed at providing preliminary information about thermal and aerodynamic loads and longitudinal stability for a similar deployable capsule, as well as information about the electronic composition of the plasma sheet and its possible influence on radio communications at the altitudes where GPS black-out could occur. Since the computer tests were carried out at high altitudes, therefore in rarefied flow fields, use of Direct Simulation Monte Carlo codes was mandatory. The computations involved both global aerodynamic quantities (drag and longitudinal moment coefficients) and local aerodynamic quantities (heat flux and pressure distributions along the capsule surface). The results verified that the capsule at high altitude (150km) is self-stabilizing; it is stable around the nominal attitude or at zero angle of attack and unstable around the reverse attitude or at 180° angle of attack. The analysis also pointed out the presence of extra statically stable equilibrium trim points.

Tolerance of eCry3.1Ab in Reciprocal Cross Offspring of eCry3.1Ab-Selected and Control Colonies of Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae).

Two new insect colonies were created by separating virgin western corn rootworm, Diabrotica virgifera virgifera LeConte, males and females from both a selected laboratory colony that was being reared on eCry3.1Ab-expressing corn (Zea mays L.) and a control colony reared on its near-isoline corn. Females from the selected colony were paired with males of the control colony and vice versa to create both a selected female by control male colony (Sel♀) and control female by selected male colony (Con♀). Both colonies along with their parental colonies (eCry3.1Ab-selected and control) were evaluated on eCry3.1Ab-expressing corn and its near-isoline in seedling assays. Larvae from each colony were also used in diet toxicity experiments in order to determine the LC50 and EC50 values for the eCry3.1Ab toxin for each. Statistical analysis of seedling assay experiments did not indicate any significant colony×corn interaction but did show a significant main effect of corn type for both larval recovery and larval head capsule widths. Results from the diet toxicity assays showed the control colony to have a significantly lower LC50 value than the selected and cross colonies and a significantly lower EC50 than the selected and Con♀ colonies. Calculations of dominance values (h) of eCry3.1Ab resistance traits from seedling assays indicated that the two reciprocal cross colonies have a dominance value (h) of ∼1, suggesting dominance of the eCry3.1Ab resistance trait.

Halide based shock-wave treatment of fluid-rich natural phases

For the synthesis of high pressure phases from natural minerals and the shock wave treatment of fluid bearing phases a halide based method was developed. The experiments were performed in the pressure range between 25 and 162 GPa with a success rate for the new method of 100% for the new method. Based on the Impedance Corrected Sample Recovery Capsule under avoiding the adiabatic decompression a direct comparison between different loading paths and sample holder geometries is possible. The recovered samples show neither indications of melting in the case of kaolinite and very limited degassing in the case of carbonates. The recovery of amorphous water bearing Al-Si-phases with Aluminum in four-, five- and six-fold coordination was possible. The samples were analyzed with scanning electron microscopy, x-ray diffraction, nuclear-magnetic-resonance- and infra-red-spectroscopy and the results were directly compared.

Uncertainties in the shock devolatilization of hydrated minerals: A nontronite case study

Controlled recovery of hydrated minerals subjected to planar shock loading is challenging because of the large difference in shock impedance between the natural samples and the engineering materials used as the recovery capsules. Significant differences in recovery capsule design confound straightforward interpretation of existing data on shock modification of hydrated minerals. We present X‐ray diffraction and infrared spectroscopy results from new shock recovery experiments on nontronite (a smectite clay observed on Mars) and identify major issues in the interpretation of recovered samples. Previous work assumes that the first shock pressure step in a ring‐up configuration is the most important factor in the interpretation of shock modification. By comparing the X‐ray diffraction and infrared spectroscopy data from experiments with similar first shock steps but significantly different final shock states, we show that one cannot simply interpret the recovered samples based upon the first shock pressure step. This work demonstrates the need for a deeper understanding of the thermodynamics of ring‐up experiments in order to be able to interpret the results in terms of an equivalent single shock loading pressure for planetary applications. In this work, we also show that venting of the samples does not matter significantly at low pressures but may be important at high pressures. We have developed a recovery method and validation test that allows us to address the major issues and technical tradeoffs with shock recovery experiments on volatile materials.

Heat fluxes and temperatures at a critical point of the frontal bluntness of the recovery capsule

The model is developed to estimate heat fluxes and temperatures at early stages of designing a system of heat-resistant coating at the critical point of the frontal bluntness of the recovery capsule without account for radiation heat flux from the air, heated behind the shock, and heat-resistant coating ablation.

Disturbance ranging in capsule atmosphere descent

A problem of evaluating disturbance significance in the statistic analysis of recovery capsule motion in atmosphere is considered. We present the results of comparing several methods, namely, iteration method of least squares, statistic linearization method and statistic test method (independently for each disturbance). The methods are compared using as an example the calculation of landing point scatter for a spherical recovery capsule that is returned from the orbit by means of a cable system.

Synthesis of Cubic Silicon Nitride in a Cylindrical Recovery Capsule

Cubic silicon nitride was synthesized from a mixture of hexagonal silicon nitride and copper powder in a cylindrical recovery capsule. It was shown that the synthesis occurred only in the region of the Mach reflection of shock waves near the axis of the capsule. A method of loading the material with ejection of the sample from the capsule into an airtight container was developed. As a result of loading, up to 20% of the starting hexagonal silicon nitride transforms to the cubic phase.

A two-step process for controlling the surface smoothness of polyelectrolyte-based microcapsules

Biocompatibility is one of the crucial requirements to be fulfilled when designing devices for immunoisolation of transplanted cells. The quality of the capsule surface (smoothness/roughness) influences the nature of cell overgrowth on it by immunocytes, which eventually may lead to the transplant failure. A microcapsule has been developed based on the polyelectrolyte complexation of the polyanions sodium alginate and cellulose sulphate with the polycation poly(methylene-co-guanidine), which was successfully tested in rodent animal models. Recently, the principles for controlling the surface smoothness of these capsules has been identified. This paper reports on a two-step process used for production of stable capsules with improved surface properties. The methodology involves separating the process of drop shape recovery and precursor capsule formation from the process of membrane formation by applying a two-reactor design. The multi-loop reactors are connected in series, and the process separation is given by the different composition of cation solutions flowing in each reactor. This process enables one to prepare the microcapsule immunoisolation device, which can differ in the extent of surface roughness and, thus, is suitable for studying the effect of surface morphology of the immunoisolation device on cell overgrowth. The effect of this process on the capsule permeability has also been evaluated.

Numerical analysis of semiconductor thermocouple operation in recording exothermic processes in a recovery capsule

Numerical simulation is used to analyze the operation of a semiconductor tin-monosulfide thermocouple. The element is used to record exothermic processes in shock-recovery experiments. We solved the problem in a one-dimensional formulation by considering a multilayer scheme that models the location of the sample and the thermocouple inside a real flat capsule. Numerical calculations yield time dependences of the thermal electromotive force(EMF) at various heat-release rates in the substance under study.

The MUSES-C, world's first sample and return mission from near Earth asteroid:NEREUS

The Institute of Space and Astronautical Science (ISAS) launches the engineering test spacecraft, MUSES-C toward a near Earth asteroid NEREUS (4660) in 2002. It is aiming at demonstrating four key technologies requisite for the future sample and return missions from extra terrestrial bodies. They are 1) An electrical propulsion, ion thrusters in interplanetary field as a primary propulsive means, 2) An autonomous guidance and navigation based on optical aid, 3) An automated sampling mechanism and 4) A direct hyperbolic reentry of the recovery capsule to the ground. This paper presents the current design status of MUSES-C focusing its attention on the contents and readiness of above mentioned key technologies.