For decades, the International Space Station (ISS) has operated as a bastion of international cooperation and a unique testbed for microgravity research. In recent years, private industry has also been affiliating with NASA and international partners to offer transportation, logistics management, and payload demands. As the costs of flying projects to the ISS decrease, the barriers limiting nontraditional partners from accessing the ISS also decrease. However, the ISS in its current form cannot be sustained forever. As NASA looks toward commercialization of low Earth orbit (LEO) and the development of a cislunar station, concrete plans for shifting the public–private relationship of the ISS are unclear. With the consistent need to continue microgravity research—from governments and private industry—understanding the socio-technical and policy issues that affect the ecosystem for future microgravity platforms is essential to maintaining an accessible and sustainable space economy. Through this work, the authors seek to evaluate the accessibility of the evolving microgravity research ecosystem. To measure accessibility, the authors propose a new framework in which accessibility is defined along new metrics of economic and administrative openness. Through case study research, the authors conducted interviews with industry experts and organizational representatives and reviewed publicly available data about microgravity research platforms from the ground to LEO. This article then leverages Systems Architecture methods to examine the stakeholders, needs, objectives, system functions, and forms for the ISS and microgravity research platforms now and in the future. Particular attention is paid toward the market dynamics affecting barriers to entry for emerging space nations and nontraditional spaceflight participants. Evaluations found that end users utilize a variety of fully public, mixed public/private, and fully private pathways to gain access to microgravity research platforms and that mixed public/private pathways fostered the highest levels of economic and administrative openness.