Thrust analysis of rocket landing on planetary granular surfaces

¹ Department of Earth and Space Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, Japan, 560 0043
² Food Engineering Department, CSIR-Central Food Technological Research Institute, Mysuru, India, 570 020

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Published online: 1 December 2025

Abstract

We systematically investigate the thrust exerted by a high-speed air jet using laboratory experiments. The study considers smooth and bumpy rigid plates, as well as a deformable granular bed that simulates planetary surfaces. A vertically downward, pressure-controlled air jet (0.01–0.3 MPa) is emitted through nozzles of varying diameters (d_n), with the nozzle-to-surface distance (h_n) adjusted to mimic the rocket’s descent. For non-deformable surfaces, thrust (T_n) increases with jet velocity (v_n), with smoother surfaces generating maximum thrust and finer grains producing greater thrust than coarser ones. At high v_n, increasing h_n enhances T_n, while its effect diminishes at lower velocities. For deformable granular beds, T_n decreases with increasing grain size (d_n), and h_n has minimal influence when erosion occurs. Narrower nozzles produce higher T_n for a constant h_n. These findings provide critical insights into optimizing thrust and landing conditions for rocket descents on diverse planetary surfaces.