Deployable Tensegrity Reflectors for Small Satellites

Future small satellite missions require low-cost, precision reflector structures with large aperture that can be packaged in a small envelope. Existing furlable reflectors form a compact package which, although narrow, is too tall for many applications.An alternative approach is proposed, consisting of a deployable “tensegrity” prism forming a ring structure that deploys two identical cable nets (front and rear nets) interconnected by tension ties; the reflecting mesh is attached to the front net. The geometric configuration of the structure has been optimized to reduce the compression in the struts of the tensegrity prism. A small-scale physical model has been constructed to demonstrate the proposed concept. A preliminary design of a 3-m-diam, 10-GHz reflector with a focal-length-to-diameter ratio of 0.4 that can be packaged within an envelope of 0.1 x 0.2 x 0.8 m^3 is presented

The Suaineadh Project : a stepping stone towards the deployment of large flexible structures in space

The Suaineadh project aims at testing the controlled deployment and stabilization of space web. The deployment system is based on a simple yet ingenious control of the centrifugal force that will pull each of the four daughters sections apart. The four daughters are attached onto the four corners of a square web, and will be released from their initial stowed configuration attached to a central hub. Enclosed in the central hub is a specifically designed spinning reaction wheel that controls the rotational speed with a closed loop control fed by measurements from an onboard inertial measurement sensor. Five other such sensors located within the web and central hub provide information on the surface curvature of the web, and progression of the deployment. Suaineadh is currently at an advanced stage of development: all the components are manufactured with the subsystems integrated and are presently awaiting full integration and testing. This paper will present the current status of the Suaineadh project and the results of the most recent set of tests. In particular, the paper will cover the overall mechanical design of the system, the electrical and sensor assemblies, the communication and power systems and the spinning wheel with its control system

A Deployable tensegrity structure, especially for space applications

The invention relates to a deployable tensegrity structure comprising, in the deployed state, a support structure (100) having a ring shape around a longitudinal axis and comprising : - a first flexible tension member (101 ) defining a first contour of said ring shape and a second flexible tension member (102) defining a second contour of said ring; - a first plurality of rigid compression members (103, 103', 103") extending between said first and second contours (101, 102), one end (1030,1030') of each rigid compression member of the first plurality being mounted on the first contour (101 ) whereas the other end (1031,1031 ") is not mounted on a contour and; a second plurality of rigid compression members (104, 104') extending between said first and second contours (101, 102), one end (1040') of each rigid compression member of the second plurality being mounted on the second contour (102) whereas the other end (1041, 1041 ') is not mounted on a contour; said first and second plurality of rigid compression members (103, 103', 103" 104, 104') being arranged with a repetitive crossing pattern around the ring; - a first plurality of flexible tension members (105, 106, 107, 110, 111 ) linking each end (1030, 1030',1040') of a compression member mounted on one of said contours (101,102) to an end of another compression member which is not mounted on one of said contours and, a second plurality of flexible tension members (108, 109, 112) linking each end (1031, 1031 ", 1041, 1041 ') of a compression member which is not mounted on a contour to an end of another compression member which is also not mounted on a contour

Study of various tensegrity modules as building blocks for slender booms

This study investigates the structural performance of long and slender tensegrity booms. Previous studies show that tensegrity structures are generally more flexible than conventional trusses or space frames. The aims here were (i) to quantify how much more flexible eleven different tensegrity booms are, when compared to state-of-the-art truss booms, (ii) to find a general explanation for this. The performance criterion used for the comparison was the first natural frequency of the boom. A finite element program with truss elements was used to compute the natural frequencies around the initial prestressed configurations. The results show that tensegrity booms have between one and three orders of magnitude lower natural frequencies than truss booms. It is concluded that for the best performing tensegrity booms, the bending stiffness is independent of the level of pre-stress and the number of infinitesimal mechanisms as the bending stiffness is given mainly by the material stiffness of the tension elements and not the geometric stiffness as the infinitesimal mechanisms are not activated by bending. Thus, whereas the level of pre-stress and the presence of infinitesimal mechanisms play major roles for the stiffness of some tensegrity structures, the axial stiffness and orientation of tension elements are most important for the studied slender booms

Making the first steps towards solar power from space- Microgravity experiments testing the deployment of large antennas

Concepts for solar power from space have received renewed attention over the past year. High costs for fossil fuel during most of 2007 and 2008 have contributed to increasing the interest not only in traditional renewable energy sources but also in options usually considered as rather "exotic". Solar power from space is one of these. Given the potential size of such an endeavour, it is particularly important to demonstrate its feasibility and convince energy sector representatives and critics via concrete demonstrator projects targeting key technologies. The construction of a light-weight, very large structure as needed for transmitting antennas and the demonstration of wireless power transmission over very large distances are two of these key technologies. The present paper presents two experiments Furoshiki-2 and Suaineadh addressing these key technologies