The Mars Gravity Biosatellite (MGB) Program is a joint project between the Massachusetts Institute of Technology and University of Queensland, in the development of a biosatellite that orbits at low earth orbit under artificial Martian gravity. The Airbag Impact Attenuation System (AIAS), is part of the Entry, Descend and Landing System (EDLS). This thesis attempts to fulfil the objectives in the development of an advanced drop test rig (DTR) and provide further improvements on the airbag design.
The Mars Pathfinder Project, Hope-X HSFD-II and the K-1 Launch vehicle provided many insights on the requirements of this investigation. It would be viable to attenuate the impact of DTR through the use of orifices to release the pressure from the airbag. Detailed analysis of the airbag fabrication process and the material selection must also be conducted to assist in the design of the AIAS for the Mars Gravity Biosatellite Program.
The DTR is a steel plate with four flanges that divides the plate into four equal quad- rants. There are twelve lead masses mounted with three on each quadrant of the plate and each lead mass weighs approximately six kilograms. A clamp ring was used to attach the airbag to the plate and an o-ring was placed in the groove of the clamp ring to ensure air tight seal between the airbag and the plate.
The airbag fabric is a non-breathable material provided by Charles Parsons® named “Commander 520". Tetrahedron patches were used to approximate the spherical shape of the airbag. Airbags were constructed with sewing machines set on \triple strength" stitches. The seams were further supported by the Bostik 1669 adhesive to enhance the strength and sealing of the stitches.
A snap shackle was used as the quick release mechanism to ensure quick and clean drops. The maximum drop height was approximately 1.4 meters, which corresponds to a maximum velocity achievable by the test rig of 5.24 m=s. In the actual tests, the DTR was dropped from a height of one meter measured from the bottom of the airbag corresponding a velocity of 4.43 m=s.
Through the drop tests conducted, it was possible to achieve an attenuation with an acceleration less than 20 g. It was recommended that “anti-bottoming" airbags be used to dampen the vibration caused by the attenuation. Both the DTR and airbag satisfied the requirements for drop tests, however, they should merely be used as preliminary prototypes. The numerical simulations model could not be verified due to the unsuccessful replicaton of the numeric simulation parameters in physical context. As suggestions for future developments, the manufacture of space-rated material and actual \dummy payload" would assist in the verification of the simulation model.