Speaker
Description
Passive thermal control of a satellite is typically performed using multilayer insulation (MLI) blankets. The current state-of-the-art method for MLI fixation makes use of stand-offs, which are glued to the spacecraft structure, and clip-washers, which fix the blankets on these stand-offs. This method is highly reliable and has a wide heritage, however it is time-consuming for several reasons: For a typical satellite more than 1000 stand-offs with variable geometries are involved. It is common that positioning clashes with adjacent hardware such as harness occur during installation, which requires lengthy clarification between AIT teams. Since the state-of-the-art stand-offs are rigid items, the stand-off holes can only be punched in the blankets after an on-site integration fit-check of the blankets is performed. All these circumstances lead to a long throughput time of blanket installation.
The goal of the ESA GSTP project “MLI Efficient Mounting” is to overcome these drawbacks by developing alternative MLI mounting systems, which considerably reduce the time effort and overall cost for MLI integration. Apart from the commercial aspects, the characteristic technical requirements were verified, such as electrical grounding, thermal performance, cleanliness, outgassing, removability, overlapping and interfaces, environmental conditions (thermal conditions, vibrations).
Based on the given specifications that both local and global mounting techniques shall be developed, different solutions were investigated over the course of the project, and a trade-off performed, ranking the options regarding their viability. In the end, two different types of local fixation elements and one global solution were selected. The local techniques focused on an improvement of the flexibility and on standardization. An alternative stand-off type has been investigated, which consists of a standardized base and a standardized shaft in the form of a ball rod, which has rotational flexibility inside the base and can be cut to length as needed. The second local solution focused on a novel type of self-adhering, reclosable fastener. The global solution makes use of standardized, lightweight secondary structure frames with pre-mounted MLI blankets. This concept also facilitates the standardization of the MLI blanket design and attachment to the structure.
A qualification campaign has been performed to aim for TRL 5. Several breadboards were manufactured representing typical spacecraft geometries. The breadboards were subjected to thermal-performance, -cycling and mechanical vibration testing. Additional sample tests, confirming temperature capability and outgassing, supported the proof of concepts. The integration feasibility of the novel concepts was demonstrated on a 2m x 2m mock-up, which represented a full-scale satellite panel including typical items, e.g. brackets, harness, radiators and pipes.
The selected attachment designs and finally qualified concepts will be subject of this talk.
