The Retractable Ultra‐lightweight (ULP) Solar Array for Retrievable Space Platforms

Retrievable space platforms, e.g. ESA's Micro ‐ gravity Platform EURECA, as shown in principle in Fig. 1, require large solar arrays which have to be retracted after operation in orbit for retrieval with the STS. The foldable ultra‐lightweight panel (ULP) solar array, developed, built and tested by MBB in the period between 1973 and 1978, represents a modern hybrid concept especially suitable for such high‐powered 3‐axis stabilised space platforms due to its advanced design features —rigid carbon‐fibre frame with pretensioned flexible cell substrate, —high stowage density by frame to frame packing with zero‐spacing, —wide power range from 1 to 12 kW due to its modular design, —high dynamic stiffness and thermal stability because of used CFRP structure material. Up to now, the solar array deployment mechanism was designed for a non‐reversible deployment and latch‐up in orbit. This design formed the basis for the development of an automatically operating retraction mechanism. This motor‐driven and motion‐controlled deployment and retraction mechanism applied on the ULP solar array will be a breakthrough for cost saving by retrieval of one of the most expensive sub‐systems of high‐power space platforms.