Jeremy A. Banik

CubeSat Deployable Antenna Using Bistable Composite Tape-Springs

In this letter, a new conductive composite tape-spring is proposed for CubeSat deployable antennas that is constructed using a glass fiber reinforced epoxy with an embedded copper alloy conductor. The tape-spring is bistable enabling the antenna to be elastically stable in both the deployed and stowed states. A dipole antenna is designed, simulated, and tested to prove the viability of the electrical properties of this material.

Synchronous Deployed Solar Sail Subsystem Design Concept

A solar sail concept has been developed from a common spiral fold pattern in order to enable a simultaneous mast and sail deployment. This novel concept utilizes the stored strain energy in a series of elastic spar members to enforce proper folding kinematics rather than relying on bulky mechanical joints. The critical inner and outer spar networks are secured to four elastically extendible masts anchored to a central drum. Deployment of the solar sail system is actuated by rotating the central drum around which the masts, spars, and film are wrapped. Tensioned radial cords deterministically unfold the membrane film under the authority of the resilient, spring-like spar members. Proper elastic behavior of the spars is an important facet to this design, and thus a significant effort was dedicated their development. This compact ground demonstration concept includes about 7.5 m 2 of reflective membrane film for useful propulsion. Features of this robust, lightweight membrane structure may prove valuable to reducing mass and increasing deployment reliability of other planar subsystems such as sun shades, solar arrays, radiators, or antenna arrays.

Development of an Elastically Deployable Boom for Tensioned Planar Structures

This paper reports on the design, analysis and testing of a new elastically deployable boom. The boom is designed such that it flattens and elastically stows around a circular hub. Using finite element analyses, a design trade was performed to determine the boom geometry that maximizes bending stiffness. Predictions of the boom’s bending and torsional stiffness and strength were also made using the finite element model. Mechanical tests of a 0.610 m boom segment were conducted to measure these properties as well. The bending stiffness test results were consistent with the finite element analysis, showing a 3.8% and 6.5% difference in stiffness about the soft axis and stiff axis, respectively. The bending buckling loads and modes shapes corresponded to those predicted by the nonlinear finite element analysis.

Stowage and Deployment Strength of a Rollable Composite Shell Reflector

This paper presents the investigation of the stowage and deployment strength of a thin composite shell capable of being rolled and stowed in a tight dual-roll or single-roll configuration. This shell is square in shape and has a doubly-curved surface for use as a segment of a larger deployable reflective aperture. Carbon fiber reinforced polymer is the material chosen for this investigation due to its stiffness, conductive, and reflective characteristics. Analysis and coupon-level testing gave confidence that a [0,±45PW,0] laminate would be rollable and resistant to creep effects at the desired roll diameter. However full-scale prototype stowage testing proved the laminate to be too stiff to be hand rolled to the dual-roll configuration at 2.5 cm diameter. An alternative laminate [±45PW,0,±45PW] proved to roll much easier but exhibited severe creep effects. High speed video footage of deployment shows the presence of snap-through over-deployment behavior, but the shell quickly settled back into the desired doubly-curved shape. Relatively short-term, five-day, stowage testing proved both shell laminates to be susceptible to creep effects due to high stored elastic strain energy. Thinner laminas and additional cross-plies are expected to reduce creep effects and improve stowage manageability by reducing overall strain energy levels.

Design Developments of a Non-Planar Deployable Structure

This paper presents a concept for a deployable structure to position and support elastic thin shell reflector segments. The structure consists of the rigid structural members and compliant hinges. The compliant hinges allow the structure to deploy into non-planar configurations without binding. Fabricated prototypes met the fundamental requirements for the scope of this work by demonstrating their ability to fold or stow without failure and to be in a stress free state in the deployed configuration. The structure assembly procedure is critical to meeting system-level surface error requirements. The selected method utilizes positioning hexapods to precisely place and hold the compliant hinges during assembly. Once all hinges are in place and verified by a metrology system, the struts are then bonded in place. This methodology guarantees the full support structure is stress free in the deployed state. The accuracy of the assembly process was characterized using a photogrammetry metrology system.

Structural Architectures for a Deployable Wideband UHF Antenna

This paper explores concepts for a wideband deployable antenna suitable for small satellites. The general approach taken was to closely couple antenna theory and structural mechanics, to produce a deployable antenna that is considered efficient in both fields. Approaches that can be deployed using stored elastic strain energy have been favored over those that require powered actuators or environmental effects to enforce deployment. Two types of concepts were developed: thin shell structure and pantograph. These concepts cover four antenna topologies: crossed log periodic, conical log spiral, helical and quadrifilar helix. Of these, the conical log spiral antenna and the accompanying deployment concepts are determined to be the most promising approaches that warrant further study.

Highly Compact Wrapped-Gore Deployable Reflector

Deployable space structures have long been investigated as a means for packaging the desired solution within the confines of the launch environment. In this study, the design of a highly compact reflector that can be stowed in a 1U CubeSat is addressed. The ideal diameter of the finished reflector is 1 meter. In order to accomplish this objective, a folding method is developed and design constraints are derived from the packaging requirement. A design method is presented in which the deployed shape is divided into gores and flattened for manufacturing. Constraints on the shape of the gores are imposed in order to produce a flat configuration with desirable stowing characteristics. Two iterations of the design are presented with deployed diameters of 0.8 and 0.5m and final stowed diameters of 16 and 14cm respectively.

Synchronous Deployed Solar Sail Concept Demonstration

for the purpose of demonstrating mechanical feasibility of the unique structural architecture. The concept features a simultaneous mast and main sail deployment scheme that is enabled by a highly deformable carbon fiber reinforced epoxy structure. Remarkably simple to manufacture, this support structure consists of uniquely shaped spar members that progressively induce tension into radial lines throughout deployment as the spars themselves are being passively tensioned by a set of four unfurlable masts. Dozens of nearly flawless deployment cycle tests were conducted on the mockup without gravity offload assistance. These tests were followed by a series of photogrammetric shape measurements taken at several stages of sail deployment. Comparison of these measurements with non-linear structural analysis predictions revealed a satisfactory correlation that validates basic modeling techniques and demonstrates the overall analyzability of the structure. Successes from the current effort have not only shown that this solar sail structural architecture is indeed feasible but that it has potential to achieve unprecedented levels of analyzability and deployment simplicity as a promising small satellite payload.

Advanced Folding Approaches for Deployable Spacecraft Payloads

Radio communications apertures for spacecraft have long been implemented using deployable architectures in order to fit within the allowable launch vehicle volume. Apertures for optics missions have traditionally not been segmented because of the tight requirements on the deployed surface. By the nature of the problem, larger apertures are generally better, but complicate orbital delivery. While there are several reflectors commercially available, high packing ratios come at very high cost due to the extremely complex nature of the designs. Researchers at the Space Vehicles Directorate have been investigating ways to enable high packing ratios while reducing the design, integration, and testing complexity of deployable systems, thereby driving down cost and enabling greater mission capabilities. Recent advances in flexible composites have opened up the possibilities of packaging apertures using either distributed or concentrated strain. This paper offers an overview of recent work done to enable lower complexity deployable apertures. Several origami-inspired designs are presented including a flat spiral folding membrane, a parabolic antenna reflector, and a phased array structure.Copyright

Deployable helical antennas for cubesats

This paper explores the behavior of a self-deploying helical pantograph antenna for CubeSats. The helical pantograph concept is described along with concepts for attachment to the satellite bus. Finite element folding simulations of a pantograph consisting of eight helices are presented and compared to compaction force experiments done on a prototype antenna. Reflection coefficient tests are also presented, demonstrating the operating frequency range of the prototype antenna. The helical pantograph is shown to be a promising alternative to current small satellite antenna solutions.