Influence of Landing Site Geology on Reentry Spacecraft Design

The influence of the ground characteristics on the structural design of entry vehicles has been noted in previous studies of sample return missions. This paper demonstrates that a proper characterization of landing site soil properties can potentially lead to a significant benefit to the system design. Consideration of such less traditional design parameters becomes more necessary as vehicles become smaller or if payload mass fractions are to be increased. These are the primary motivations for this research. Often, programmatic factors will drive the choice of landing site, but the results here indicate that there could be strong technical gains to be made by selecting one site over another or, at the very least, for undertaking a proper characterization of the terrain at the intended landing site, rather than using generic data. The paper reports on experiments conducted on soil from the Woomera test site in Australia and Sydney beach sand to compare against previous studies of the Utah Test and Training Range soil. Results indicate that at least a factor of 2 reduction in the peak deceleration would be experienced when landing in Woomera as compared with Utah, leading to the potential for a lighter entry vehicle or more payload.