constrained to not extend upward into the vertical space of the stack of modules 200 however this constraint may be relaxed to accommodate the arrangement of solar panels in a launch configuration as illustrated in fig4 a fig4 a illustrates an arrangement of a spacecraft 100 using conventional fold away solar panels 410 in a conventional design the design of each module must be coordinated so as to avoid interference with the solar panels or other external components to facilitate modular design the constraints placed on modules 200 preferably include a distance dl beyond which external elements of the module 200 are not permitted to extend if all of the modules 200 conform to this constraint an anchor module with fold away solar panels 410 can be designed independently of the particular modules 200 that form the stack as is well known in the art however the use of fold away solar panels requires a substantial amount of design effort because these external panels 410 introduce a substantial moment arm factor that must be taken into account in the mechanical design of the entire spacecraft in a modular design each module 200 must be capable of supporting the remainder of the stack of modules in the presence of the forces that the panels 410 introduce during launch and during deployment in a preferred embodiment the.