Abstract
Experiments conducted onboard the International Space Station help investigate the physiological changes that living organisms undergo in microgravity. On Earth, the two-axis clinostat serves as an alternative that can continuously change the direction of gravity and simulate microgravity conditions by time-averaging the gravity vector. However, its structural characteristics inevitably produce poles where gravity is unevenly concentrated. This study conducted a quantitative analysis and comparison of pole formation across four representative clinostat control strategies. To evaluate the poles, two quantitative indicators were defined. The commonly used control strategies, maintaining a constant angular velocity or following a random distribution, were found to induce severe poles. In contrast, when the angular velocity of the external motor followed a specifically designed reciprocal sinusoidal profile, pole formation could be significantly reduced by adjusting the ratio between the minimum and maximum angular velocities. These trends, identified through simulations, were further validated through experiments using an inertial measurement unit.
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These data that support the findings of this study are available from the corresponding author upon reasonable request.
References
Fitts, R. H. et al. Prolonged space flight-induced alterations in the structure and function of human skeletal muscle fibres. J. Physiol. 588, 3567–3592 (2010).
Riley, D. A. et al. Decreased thin filament density and length in human atrophic soleus muscle fibers after spaceflight. J. Appl. Physiol. 88, 567–572 (2000).
Trappe, S. W. et al. Comparison of a space shuttle flight (STS-78) and bed rest on human muscle function. J. Appl. Physiol. 91, 57–64 (2001).
Baldwin, K. M., Herrick, R. E., Ilyina-Kakueva, E. & Oganov, V. S. Effects of zero gravity on myofibril content and isomyosin distribution in rodent skeletal muscle. FASEB J. 4, 79–83 (1990).
Lewis, M. L. et al. Spaceflight alters microtubules and increases apoptosis in human lymphocytes (Jurkat). FASEB J. 12, 1007–1018 (1998).
Williams, D., Kuipers, A., Mukai, C. & Thirsk, R. Acclimation during space flight: Effects on human physiology. CMAJ 180, 1317–1323 (2009).
Mehta, S. K., Stowe, R. P., Feiveson, A. H., Tyring, S. K. & Pierson, D. L. Reactivation and shedding of cytomegalovirus in astronauts during spaceflight. J. Infect. Dis. 182, 1761–1764 (2000).
Boonyaratanakornkit, J. B. et al. Key gravity-sensitive signalling pathways drive T cell activation. FASEB J. 19, 2020–2022 (2005).
Villa, A., Versari, S., Maier, J. A. & Bradamante, S. Cell behavior in simulated microgravity: A comparison of results obtained with RWV and RPM. Gravit. Space Biol. Bull. 18, 89–90 (2005).
Hatton, J. P. et al. The kinetics of translocation and cellular quantity of protein kinase C in human leukocytes are modified during spaceflight. FASEB J. 13, S23–S33 (1999).
Cogoli-Greuter, M. The lymphocyte story—An overview of selected highlights on the in vitro activation of human lymphocytes in space. Microgravity Sci. Technol. 25, 343–352 (2014).
Schwarzenberg, M. et al. Signal transduction in T lymphocytes-A comparison of the data from space, the free fall machine and the random positioning machine. Adv. Space Res. 24, 793–800 (1999).
Walther, I. et al. Simulated microgravity inhibits the genetic expression of interleukin-2 and its receptor in mitogen-activated T lymphocytes. FEBS Lett. 436, 115–118 (1998).
Hoson, T., Kamisaka, S., Masuda, Y., Yamashita, M. & Buchen, B. Evaluation of the three-dimensional clinostat as a simulator of weightlessness. Planta 203, S187–S197 (1997).
Nishikawa, M. et al. The effect of simulated microgravity by three-dimensional clinostat on bone tissue engineering. Cell Transpl. 14, 829–835 (2005).
van Loon, J. J. W. A. Some history and use of the random positioning machine, RPM, in gravity related research. Adv. Space Res. 39, 1161–1165 (2007).
Borst, A. G. & van Loon, J. J. W. A. Technology and developments for the random positioning machine, RPM. Microgravity Sci. Technol. 21, 287–292 (2009).
Kim, Y. J. et al. Time-averaged simulated microgravity (taSMG) inhibits proliferation of lymphoma cells, L-540 and HDLM-2, using a 3D clinostat. Biomed. Eng. OnLine 16, 48 (2017).
Jeong, A. J. et al. Microgravity induces autophagy via mitochondrial dysfunction in human Hodgkin’s lymphoma cells. Sci. Rep. 8, 14646 (2018).
Kim, S. M. et al. An experimental and theoretical approach to optimize a three-dimensional clinostat for life science experiments. Microgravity Sci. Technol. 29, 97–106 (2017).
Kim, D. et al. Customized small-sized clinostat using 3D printing and gas-permeable polydimethylsiloxane culture dish. npj Microgravity 9, 63 (2023).
Wuest, S. L. et al. A novel microgravity simulator applicable for three-dimensional cell culturing. Microgravity Sci. Technol. 26, 77–88 (2014).
Kim, Y. J. et al. Manufacturing and control of a robotic device for time-averaged simulated micro and partial gravity of a cell culture environment. Int. J. Control Autom. Syst. 18, 53–64 (2020).
Manzano, A. et al. Novel, Moon and Mars, partial gravity simulation paradigms and their effects on the balance between cell growth and cell proliferation during early plant development. npj Microgravity 4, 9 (2018).
Hammond, T. G. & Hammond, J. M. Optimized suspension culture: The rotating-wall vessel. Am. J. Physiol. Ren. Physiol. 281, F12–F25 (2001).
Clary, J. L. et al. Development of an inexpensive 3D clinostat and comparison with other microgravity simulators using Mycobacterium marinum. Front. Space Technol. 3, 1032610 (2022).
Kim, S. C. et al. Effects of simulated microgravity on colorectal cancer organoids growth and drug response. Sci. Rep. 14, 25526 (2024).
Choi, D. H. et al. 3D cell culture using a clinostat reproduces microgravity-induced skin changes. npj Microgravity 7, 20 (2021).
Malczyk, M., Blachowicz, T. & Ehrmann, A. Coupled system of dual-axis clinostat and Helmholtz cage for simulated microgravity experiments. Appl. Sci. 14, 9517 (2024).
Song, C. et al. Preparation for mice spaceflight: Indications for training C57BL/6J mice to adapt to microgravity effect with three-dimensional clinostat on the ground. Heliyon 9, e19355 (2023).
Yotov, V. V., Marovska, J., Turiyski, V. & Ivanov, S. I. A new random positioning machine modification applied for microgravity simulation in laboratory experiments with rats. Inventions 7, 85 (2022).
Ye, Y. et al. Conserved mechanisms of self-renewal and pluripotency in mouse and human ESCs regulated by simulated microgravity using a 3D clinostat. Cell Death Discov. 10, 68 (2024).
Kim, T. Y. Theoretical study on microgravity and hypogravity simulated by random positioning machine. Acta Astronaut 177, 684–696 (2020).
Rojas-Moreno, A. & Santos-Rodriguez, F. Design of a novel 3DOF clinostat to produce microgravity for bioengineering applications, in: Proc IEEE XXV Int Conf Electron Electr. Eng. Comput. (INTERCON), August 2018, IEEE, New York, 2018, pp. 1–4.
Cacayurin, CRC et al. (2023). An engineered design of 3-axis clinostat for simulated gravity experiments in astrobotany. In: Proc IEEE 15th Int Conf Humanoid Nanotechnol Inf Technol Commun Control Environ Manag (HNICEM), November 2023.
Braveboy-Wagner, J. & Lelkes, P. I. Impairment of 7F2 osteoblast function by simulated partial gravity in a Random Positioning Machine. npj Microgravity 8, 20 (2022).
Benavides Damm, T., Walther, I., Wüest, S. L., Sekler, J. & Egli, M. Cell cultivation under different gravitational loads using a novel random positioning incubator. Biotechnol. Bioeng. 111, 1180–1190 (2014).
Acknowledgements
This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (No. RS-2024-00458826) and by a grant of the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health & Welfare, Republic of Korea (Grant No. HI19C1352). It was also supported by Industrial Technology Innovation R&D Program of MOTIE/KEIT (Project No. 25421092), Development of a therapeutic endoscopic system incorporating a motorized autonomously controlled endoscopic scope - featuring over 5,000 cycles of durability, bending capability exceeding 180°, and IPX7 waterproof rating - and an AI-based image processing unit, aimed at localization of endoscopy systems and improving the success rate of endoscopic treatments.
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Y.J.K. proposed the indices for pole evaluation, conducted simulations, and drafted the manuscript. S.P. fabricated clinostat hardware, performed IMU-based experiments, and drafted the manuscript. Y.J.K. and S.P. contributed equally to this work. As the corresponding author, S.K. supervised the entire research process and the preparation of the manuscript.
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Kim, Y.J., Park, S. & Kim, S. Comparison of clinostat control strategies to achieve simulated microgravity with uniform gravity vector distribution. npj Microgravity (2026). https://doi.org/10.1038/s41526-026-00570-8
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DOI: https://doi.org/10.1038/s41526-026-00570-8
