SPLESA: Small Planetary-Surface Lightweight Solar Arrays
Bernasconi, M.C1; Zenger, R2
1MCB Consultants; 2RUAG Aerospace
The execution of payloads of opportunities or piggyback elements riding alongside a major mission is often hampered by power limitations. In particular, different efforts based on small planetary lander payloads have given initial consideration to the use of deployable solar array structures, but eventually has to accept lower-power, fixed panels because of the excessive complexity and absolute mass of available traditional options. Accordingly, one can identify a need for modestly-sized (<10 m2) but very-efficiently-stowed items, for which the major issue concerns the feasibility of shrinking a complete array (i.e. including deployment elements) into a package with a mass limited to 2-4 kg.
We report on a concept marrying "inflatable" structures with thin-film devices that builds on a fair amount of heritage projects to make such a product possible in the near-term. Work to date has looked at three different technologies for the expandable support structure: in addition to pure inflatable members (for short-duration applications), we assessed generic chemically-rigidized expandable structural (CRES) elements, as well as taken a first look at elastic recovery options. These discussions have proceeded in parallel with preliminary design definition activities. Because of the small objects under consideration here (about 3.5 m in extension), both circular and square frames can be envisioned and compared.
For the critical stowage and deployment aspects, we identified a simple scheme, with development tests heritage covering the unfolding of membrane surfaces at least up to 10 m2. Together with the assessed mass penalty, under conservative assumptions, this packaging volume leads to volumetric power densities at 200 kW/m3 - or better, depending on the array's size. These results are assessed in comparison with other primary power sources.
Finally, after mentioning issues like separation from the carrier, deployment actuation, avoidance of excessive interaction with the terrain at the lander's location, we outline a development plan for a near-term realization of such an item, building upon various technological projects that have accumulated a solid heritage base.
In conclusion, one can remark that, while inflatable gossamer structures generally receive attention as enabling the realization of large elements, the application discussed here addresses a rather small structure that could profit from those technologies. The analysis has showed that inflatable solar arrays do offer potential benefits for small lander. Once available, such an object could come to support other functions like powering individual elements of a sensor network, charging station for mini-rovers, and more.
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