Thursday, 23 February 2012

Description of the REXUS 13/14 sounding rocket experiment SAM

In the following the layout of the REXUS13/14 sounding rocket experiment SAM will be described. The deployable structure of SAM consists of two rows of spherical cells that are deployed by using the expansion of trapped air in the spheres when subjected to vacuum (space) conditions. The two layers of spheres are manufactured out of 30micron reflectively coated Mylar. Each cell is manufactured by heat welding circular sheets of Mylar together. The diameter of each cell is 14 cm; the diameter of the entire structure is 98 cm. The connection between the ejectable module and the deployable structure is obtained with an adhesive.

In order to change the shape of the structure, micro pumps are added to vary the trapped air pressure between two neighbouring cells. The pressure change in these cells will then change the volume of the two spheres and therefore change the shape of the entire structure. This bio-inspired structure originates from the heliotropism of plants (movement of plants towards the sun).

Mp6 micro pumps from Bartels Mikrotechnik GmbH (Dortmund, Germany) are used to change the pressure between two cells. There will be two pumps mounted to the inside wall of the deployment storage. The rows of spheres closest to the sides of the cube are joined to form one big actuator. The micro pumps will pump the residual air from the bottom to the top layer of Actuator 1 to lift up the up side and respectively from the bottom to the top layer of Actuator 2 to lift up the down side of SAM. The control software will alternate between the actuation of Actuator 1 and Actuator 2. A more precise actuation timeline needs to be validated by tests of the pumps and the structure in the vacuum chamber.

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