Description: Thin, flexible, and highly efficient solar arrays are needed that package compactly for launch and deploy into large, structurally stable high power generators. Inverted Metamorphic Multi-junction (IMM) solar cells can enable these arrays, offering higher efficiencies of >33% and lower mass and flexibility, but integration challenges of this thin crystalline cell technology need solution. The Thin Hybrid Interconnected Solar-Array (THINS) technology allows robust and reliable integration of IMM cells into a flexible blanket comprising standardized modules engineered for producibility. The modules support the IMM cell by using multi-functional materials for structural stability, shielding, CTE stress relief, and integrated thermal and electrical functions. The Phase I effort demonstrated the feasibility of key THINS component, including the structurally stabilized IMM cell, and integration with advanced multi-functional substrate and superstrate components, and completed the modularity approach for interfacing into the Roll Out Solar Array (ROSA) deployable structure, while improving standardization and manufacturability. Design evaluation shows figures of merit for array level specific power, including deployable structure, greater than 400W/kg and volumetric efficiency greater than15kW/m^3, significantly higher than current approaches. The low mass and low stowed volume provides a path to package 300kW in a single launch with a deployment approach that uses simple, robust mechanisms. Phase II advances the THINS/ROSA technology, incorporating advanced 4 -Junction IMM solar cells into THINS modules using demonstrated spaceflight qualified materials, testing module coupons in thermal cycling and plasma environments, fabricating a full-scale module to demonstrate automatable manufacturing processes, integrating that module and inactive modules (with cell simulators) into the ROSA deployable structure, and culminating in a full-scale deployment demonstration.

Benefits: NASA technology objectives have traditionally included solar arrays with high specific power, high power capability, high voltage capability, compact packaging, and modularity for improved schedule responsiveness, standardization, qualification traceability, automation, and lowered cost. Lightweight, high power solar arrays with compact packaging is a key enabling technology for meeting NASA goals of establishing a capability for Solar Electric Propulsion (SEP), as well as for long-duration manned missions. In particular, providing tens to hundreds of kilowatts can be enabling for outer planetary missions, allowing improved SEP performance during cruise, and providing significant power (hundreds of watts) for the objective mission, despite the minimal sunlight available at the asteroid belt, Jupiter and beyond. The THINS/ROSA array also has the advantages of improved electromagnetic cleanliness because of the capability for flex-circuit back-wiring, encapsulation, and the continuity of coverglass materials to create a continuous grounded, shielded enclosure. Such a technology can be enabling for high performance electric and magnetic field instruments often used on NASA science spacecraft, such as THEMIS, MMS, and Maven, and could also enable the higher voltages needed for direct drive SEP approaches.

The ability to fit tens of kilowatts in a compact stowage envelope is of great benefit to commercial missions, where high power translates directly to improved spacecraft revenue. Improvements in reliability and reduced costs are also of great interest to commercial spacecraft suppliers, since the solar array can often drive the total spacecraft and launch costs, and reliability is needed to avoid the failures that drove up costs of commercial missions significantly in recent years. The ability to package high power with compactness can significantly reduce launch costs by enabling smaller, economical launch vehicles, and high efficiency reduces cost by reducing solar array area and therefore the required hardware and station-keeping costs. The modularity concept provides a means of improving process control and standardization to improve reliability and reduce the cost of manufacturing and qualification. Significant interest in this technology has been expressed from commercial spacecraft providers such as Boeing, Orbital Sciences and Loral. Vanguard has been working extensively with Boeing on its development of high power, flexible arrays, such as the Integrated Blanket Interconnect System (IBIS), which is a version of Boeing's High Power Solar Array (HPSA) that incorporated earlier versions of THINS, and which would benefit from the technology maturation achievable with the continuation of this SBIR.