Wire Boom Research Articles

The Electric Field Instrument (EFI) for THEMIS

The design, performance, and on-orbit operation of the three-axis electric field instrument (EFI) for the NASA THEMIS mission is described. The 20 radial wire boom and 10 axial stacer boom antenna systems making up the EFI sensors on the five THEMIS spacecraft, along with their supporting electronics have been deployed and are operating successfully on-orbit without any mechanical or electrical failures since early 2007. The EFI provides for waveform and spectral three-axis measurements of the ambient electric field from DC up to 8 kHz, with a single, integral broadband channel extending up to 400 kHz. Individual sensor potentials are also measured, providing for on-board and ground-based estimation of spacecraft floating potential and high-resolution plasma density measurements. Individual antenna baselines are 50- and 40-m in the spin plane, and 6.9-m along the spin axis.

Practical Design and Flight Test of a Yo-Yo Wire Boom Deployment System

Ay o-yo-type wire-boom deployment system has been developed and flight tested on a sounding rocket mission. The goal of the work has been to validate a new mechanism that rapidly deploys wire booms from a spinning spacecraft. This work takes a theoretical system design and implements it in practical hardware. The limitations inherent in practical hardware necessitated new theoretical developments. A modified stability analysis has been developed for the case of nonzero axial separation between the wire-boom base attachment points and the spacecraft’s center of mass. This modified stability analysis dictates that a stable design is impractical for many missions because very large wire-boom tip masses are needed and because the three-dimensional deployment transients are very sensitive to small asymmetries. This problem has led to the development of design criteria and analysis techniques, which permit a short-duration mission to use a slightly unstable nutation mode. These techniques have been used to design a system that has been flown on two daughter spacecraft that were part of a formation of three sounding rocket subpayloads. Each daughter spacecraft deployed four 3-m-long wire booms in under 10 s and maintained a low level of spin instability for the remaining 700 s of the mission. The nutation oscillations showed a slow exponential growth, but the coning half-angles of both spacecraft never exceeded 16 deg.

Astrid-2, an advanced microsatellite for auroral research

Abstract. The successful launch of the Swedish microsatellite Astrid-2 in December 1998 began a new era of auroral research, with advanced microprobes of 30 kg or less used as research tools. Innovative technologies and low-mass solutions were used for the sensors and deployment systems to allow a fairly complete set of scientific instruments within the 10 kg allocated for the scientific payload. A newly developed wire boom deployment system proved to function excellently. During its seven month lifetime Astrid-2 collected more than 26 Gbytes of high-quality data of auroral electric and magnetic fields, and auroral particle and plasma characteristics from approximately 3000 orbits at an inclination of 83° and an altitude of about 1000 km. Scientific results cover a broad range of topics, from the physics of energization of auroral particles to how the magnetosphere responds to the energy input from the solar wind and global magnetic field modelling. The fulfilment of both the technological and the scientific mission objectives has opened entirely new possibilities to carry out low-budget multipoint measurements in near-Earth space.Key words. Ionosphere (auroral ionosphere; instruments and techniques) – Magnetospheric physics (auroral phenomena)

Rapid Energy Dissipation in a Yo-Yo-Type Wire Boom Deployment System

A wire boom deployment system has been developed that uses a mechanism that is similar to the classic yo-yo despin mechanism. The goal has been to develop a way to rapidly deploy wire booms from a spinning soundingrocket experiment. The main challenge in using a yo-yo-type mechanism is to dissipate the excess kinetic energy so that the wire booms do not rewrap themselves about the spacecraft after deploying. A ring has been added to the basic yo-yo mechanism. It rotates with respect to the main spacecraft about the nominal spin axis, and the wire boomsdeploy from it. Thering/spacecraftjoint isdamped, and relativemotion betweenthering and thespacecraft dissipates the excess energy. This system is analyzed and simulated in two and three dimensions. The results show that a well-tuned system can deploy 2.5 m wire booms in under 20 s and that it can tolerate the expected levels of asymmetry and parametric uncertainty.

Signatures of storm sudden commencements in the electric field measured at geostationary orbit (GEOS-2)

GEOS-2 carried a long wire boom antenna to measure the ambient electric field. In view of the long successful operation of the spacecraft a vast amount of electric field data was accumulated between 1978 and 1983. A survey of the data set revealed about 90 sudden occurrences of large amplitude Pc5 type waves. It turned out that about half of these events were associated with SSC's recorded on ground. We describe how the electric field and the computed E × B/B2 plasma drift changed from the undistrubed pre-SSC periods to the initial tens of seconds after the sudden compression occurred. The typical picture obtained from these events is that SSC's detected by GEOS-2 near local noon show a clear compressional plasma drift pattern, i.e., E × B/B2 points tailward. Close to the flanks or in the nightside these signatures contain not only a tailward flow proper but also a radially inward component. The magnetic field signatures show that the compressional component is strongest around local noon with a remarkable decrease via the flanks toward local midnight. Our data indicates that SSC's are hardly detectable in the geostationary orbit near local midnight. Based on simple geometrical considerations and within the accuracy of the ground recording times of the SSC's (±30s) we derive propagation velocities for the radially inward travelling compressive wave of 950 km/s and for azimuthal directions in the outer magnetosphere 1100 km/s.

Dynamics of wire boom oscillations on a spinning satellite Part I, Lagrangian equations of motion and transient response

This paper reports on the results of a theoretical formulation on the dynamics of a spinning satellite with four extendable/retractable wire booms each with a tip mass attached. Seven coupled nonlinear equations of motion of hub and boom oscillations in the spin plane are derived from the Lagrangian and solved on a computer to generate simulations of time-dependent dynamical behavior of the satellite system under different boundary conditions. The transient response of the system due to perturbations by wire boom extension/retraction is derived analytically by means of the Laplace transform method.

Dynamics of wire boom oscillations on a spinning satellite Part II, normal modes in spin plane

Harmonic analysis of the normal modes in the spin plane of a satellite with four hinged wire booms each with a tip mass attached is presented. Analytical expressions of normal mode coordinates and frequencies are obtained by solving the matrix eigenvalue equations, using secular determinant and simultaneous diagonalization methods. Translational oscillation of the center body is present in configurations of lower symmetry. The analytical results are in good agreement with computer simulations.