Martin Hillebrandt

Testing of the Deorbitsail drag sail subsystem

Deorbitsail is a 3U Cubesat project that will launch, deploy, and support a large drag sail deorbiting payload. The flight payload sail system will deploy to 5 by 5 meters, increasing the frontal area of the spacecraft dramatically. A series of 4-by-4-meter sail deployments has been performed with a prototype of the proposed system. The prototype system tests included partial deployments in environmental chambers and full-scale deployment at ambient lab conditions. Design changes arising from testing of the sail system prototype are described in this paper. Engineering model construction is underway and the Deorbitsail launch will be in 2014. Deorbitsail is a European Commission 7th Framework Programme project with nine partner organizations.

Deployment Testing of the De-Orbit Sail Flight Hardware

The paper describes the results of the deployment testing of the De-Orbit Sail flight hardware, a drag sail for de-orbiting applications, performed by DLR. It addresses in particular the deployment tests of the fullscale sail subsystem and deployment force tests performed on the boom deployment module. For the fullscale sail testing a gravity compensation device is used which is described in detail. It allows observations of the in-plane interaction of the booms with the sail membrane and the central satellite body to which the booms and sails are attached. During the tests issues with the sail deployment tests were encountered which lead to design changes regarding the sail and type of sail attachment.

A New Deployable Truss for Gossamer Space Structures

A new deployable mast for realization of large, deployable space structures such as antennas of high arperture, long instrument booms, large solar arrays or solar sails has been developed at the DLR. The triangular truss is based on the use of longerons of composite tapes and shows a signicant increase in mass eciency compared to existing deployable mast concepts. The longerons of thin carbon bre tapes enable realization of large cross-sectional dimensions which leads to a strong insensitivity of critical compression load towards element length. Thereby, in comparison to trusses with longerons of solid rods - the most commonly used type of longerons - higher truss bay length and radius can be achieved for a lower amount of structural mass. This directly contributes to bending stiness and strength. The folding mechanism makes use of the high deformation capability of longerons of tapes in attened state. It is based on a two path folding pattern where the truss is attened rst in cross-direction and reeled up afterwards. This is enabled by the combined use of exible longerons and hinges added to one batten row and ensures high volume eciency. This is especially true for very long masts as the stowage volume mainly depends on the intial reeling radius.