Space Station/Shuttle Orbiter dynamics during docking

Mathematical models of a reference space station configuration (Power Tower) and a Space Shuttle Orbiter are developed and used to study the dynamic behavior of the Space Station/Orbiter system just prior to and subsequent to an impulsive docking of the two spacecraft. The physical model of the space station is a collection of rigid and flexible bodies. The orbiter is modeled as a rigid body. An algorithm developed for use in digitally simulating the dynamics of the system is described and results of its application are presented

Finite element models of wire rope for vibration analysis

The usefulness of wire rope in shock and vibration isolation is briefly reviewed and its modeling for the purpose of vibration analysis is addressed. A model of a nominally straight segment of wire rope is described in which the rope structure is represented by a maiden, or central, strand of wire with one (or more) strand(s) wrapped around it in a helix (helices). The individual strands are modeled using finite elements and MSC NASTRAN. Small linear segments of each wire are modeled mathematically by dividing them lengthwise into triangular prisms representing each prism by a solid NASTRAN element. To model pretensioning and allow for extraction of internal force information from the NASTRAN model, the wound strands are connected to the maiden strand and each other using spring (scalar elastic) elements. Mode shapes for a length of wire rope with one and fixed to a moving base and the other attached to a point mass, are presented. The use of the NASTRAN derived mode shapes to approximate internal normal forces in equations of motion for vibration analyses is considered

Initial investigations into the damping characteristics of wire rope vibration isolators

Passive dampers composed of coils of multi-strand wire rope are investigated. Analytical results range from those produced by complex NASTRAN models to those of a Coulomb damping model with variable friction force. The latter agrees well with experiment. The Coulomb model is also utilized to generate hysteresis loops. Various other models related to early experimental investigations are described. Significant closed-form static solutions for physical properties of single-and multi-strand wire ropes are developed for certain specific geometries and loading conditions. NASTRAN models concentrate on model generation and mode shapes of 2-strand and 7-strand straight wire ropes with interfacial forces

New Laboratory-Based Satellite Impact Experiments for Breakup Fragment Characterization

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Tracking The Trajectory Of Space Debris In Close Proximity Via A Vision-Based Method

The increasingly cluttered environment in space is placing a premium on future spacecraft and satellites that are capable of tracking and estimating the trajectory of unknown space debris autonomously without consistent communication with ground stations. In this paper, a vision-based debris trajectory-tracking method in close proximity is presented using two cameras onboard of two satellites in a formation. To differentiate the target debris from other clutters, a data-association technique is investigated. A two-stage nonlinear robust controller is developed to adjust the attitude of the satellites such that the target debris can be maintained within the field of view of the onboard cameras. Capabilities of the proposed estimation and control methods are validated in the simulations. © 2014 American Society of Civil Engineers

Rapid, automated, test, verification and validation (v&v) for the CubeSats

Bringing up of a small-scale mission assurance and engineering workflow is described. The experiences learned in the ZACUBE-1 mission prompted the development of an automated systems engineering platform leading to conformity in system design, test, and verification. The platform implements the methodology of systems engineering by coordinating diverse elements of the lifecycle and by incorporating the tools involved. The phase B/C activities of system modelling, simulations, prototyping, and design may be unified to a compounding effect and raising the level of the system view. The Verification and Validation (V&V) is achieved by integrating a test and measurement facility to the platform. With the platform, we accomplish rapid electrical and functional test and verification of the CubeSat subsystems and thermal validation in 20 °C to +50 °C cycle. The platform is automated by an application software which executes functional and thermal environment tests and provides support for requirements flow, system definition, embedded development, and simulations by integrating real-time target hardware. The platform is exploited in validating an S-band communications subsystem while economizing time and obtaining valuable insight into transmission performance under thermal loading

Editorial Perspectives on Industry-Integrated Engineering and Computing Education and Fostering the Socio-Economic Development Role of Engineering and Technology Schools

International audienc