This paper presents highly adaptive small satellites (HASSs) experiment for space mission modelling. This experiment seeks to unravel an unprecedented significant reduction in the flight validation cycle by providing a test platform for robust space mission technology(s). The experimental setup has three candidate field programmable gate arrays (FPGAs) representing the model satellites. The ground station is a relay PC (with an FPGA card) running a real-time operating system. The data and communication network are a deterministic Ethernet. The ground station transmits an FPGA code to configure a satellite(s) to operate in a particular mode. The experimental modelling incorporates a preprogrammed mode change capability based on satellite attitude/orientation in space. The model analysis results reveal reliable, multifunctional, reconfigurable, and cheap space missions with allowance for a HASS reuse. Hence, integrated and adaptive payload systems employing the HASS architecture can now be reliably and sustainably designed, tested, and space qualified.