Recently completed activities
This study has demonstrated that Inflatable structure technology based on rigidization technique using high latency epoxy resin is feasible with low needed power level.
The remaining concern to be solved is the leakage control of beam that should take advantage of the already existing sealing techniques used for inflatable boats or life jacket.
Solar Arrays and Earth Observation Antenna applications are the most interesting candidate applications for a future in-orbit demonstration since they offer the widest and short term market opportunities.
For Solar Array applications, the development of low mass cell assembly is necessary to make inflatable technology attractive over today technology. For antenna applications, no blocking have been evidenced on beam and membrane that requires reasonable development effort on design and materials.
The manufacturing and test campaign that has been conducted has first confirmed that UV radiation can be used to rigidise inflatable structures, even though a thermal control layer is required to provide in orbit an appropriate temperature distribution. No electric heating or lighting and therefore no harness are required. This test campaign was essentially focused on the comparison of various wall construction concepts to get a much deeper view of the pros and cons of the different designs that can be used to build inflatable space structures.
Still improvements can be pursued, particularly regarding the materials and possibly fibre lay-up. The woven construction is ideal for cylinders but may even be extended to more complex configurations. The fibreglass fabric internal facing could be impregnated with a silicone airtight layer in order to get rid of the internal bladder. An efficient thermal control has to be designed to guarantee an appropriate temperature, a low transverse gradient to prevent boom bending and limited ageing effects. There are indeed many improvements which can be investigated and provide interesting solutions for inflatable structures designers.
In the first step, the team performed a review of the requirements, solar cells and flexible blanket technologies and existing deployable support structures. Then, a brainstorming session and a trade-off study lead to the selection approved by ESA, of a reference concept based on a central inflatable and rigidizable boom with two deployable lateral membranes. This concept showed advantages in terms of mass and manufacturing costs compared to the existing concepts. Following this design selection, the design and development plan has been defined.
The second phase of the project consisted in the preliminary mechanical and thermal design and analysis of a full-scale 1500 W solar array. Then a breadboard was derived using dedicated scaling rules.
In the third step, the breadboard was manufactured and tested. The testing campaign was very successful. It enabled to demonstrate on ground the feasibility of the deployment and the rigidization of an inflatable rigidizable structure.
The Alternative Descent and Landing Technologies programme has established the necessary requirements for the design of a conventional entry, descent and landing system. A robust design has been produced to these requirements incorporating a vented airbag landing system. This DM design had a mass over 100 kg lighter than one incorporating an unvented airbag.
Detailed design or identification of all the components of the descent and landing system has been carried out as well as a full assessment of the predicted performance of the system under the specified conditions.
The system is now in a state to be taken forward into a full development programme. The high risk items, and therefore the priority for this programme, have been identified and a plan for the final verification of the system established with a series of end-to-end tests.
The maturity of the vented airbag landing system has been significantly advanced by the manufacture and testing of prototype airbags and the associated control systems. The tests have indicated that the vented airbag may provide a significant advantage over an unvented system in terms of system mass, although further testing is required to verify their suitability for future missions.
Several improvements have been introduced in SAMCEF during the PASTISS project, they are related to: the inflation, the analysis of inflated thin structure, the wrinkling of thin membrane, the definition of the initial shape, the fluid structure interaction, etc.
A catalogue of benchmark cases for the analysis of inflatable structures has been developed by the structures section. The catalogue is available in PDF format.
Last update: 18 June 2007