Assembly and Deployment of Large Space Structures

In 2021, NASA LaRC published a survey of their research into large space structures (Dorsey et al., 2021) (link), which is summarized as follows. In the 1960s, two concepts were developed for a large space reflector and a communication satellite. In the 1980s, LaRC conducted testing of a 5 m cubic truss, with 2 in diameter struts, for the main structure of the proposed Space Station Freedom (SSF), using an erectable node and a joint system and testing simulated ISA in a neutral buoyancy tank (Watson et al., 1988)
⁸. Then, the SSF truss was adapted to a scaled-down 1-in cross-sectional diameter version and changed from a cubic framework to a tetrahedral structure to test a precision segmented reflector (PSR) concept. This involved assembling a 14 m test structure with a team of two astronauts in a neutral buoyancy tank (Bush et al., 1991) (link) (Pawlik et al., 1989) (link). In the early 2000s, NASA LaRC also investigated assembling truss structures using robots in their Automated Structures Assembly Laboratory (ASAL), where they assembled an example telescope backplane tetrahedral truss structure from 102 2-m long struts (Doggett, 2002) (link). Newer telescope structures are in development called Tri-Trusses, which are a concept for a deployable truss that could be assembled to create the backplane of a large space telescope on the order of 20 m in diameter (William et al., 2019) . In 1985, NASA conducted the Assembly Concept for Construction of Erectable Space Structure (ACCESS) experiment during an Extravehicular Activity (EVA) outside the shuttle where two astronauts assembled a 13.7 m long structure (Heard et al., 1986) (link). In 2017, as a part of the previously mentioned CIRAS project, NASA LaRC assembled a 32-in cubic truss using a team of robots. This was a strut-by-strut assembly where struts were grabbed by the Strut Attachment, Manipulation, and Utility Robotic Aide (SAMURAI) at the end of a LRM, and then handed off to the NINJAR, which precisely positioned them until a full truss bay was assembled and then lifted (Wong et al., 2018) (link). Additional truss bays could then be constructed below to create any tower of any consisting desired bays. Overall, there are many other examples of structures in space, but this shows how many examples can be found for either assembling a truss strut-by-strut or assembling deployed units either robotically or with astronauts. The idea of having a mixed assembly scheme, as has been described in this paper, could not be found previously published though it is obvious that mixed methods of assembling and deploying structures are heavily used in space exploration. For example, the ISS was created with a mixture of launching prefabricated modules, docking them together to assemble, and deploying large truss units such as those for the solar arrays to create the final station structure and desired functionality.