This study investigates the impact of Washingtonia palm biomass on clayey soil shear strength using experimental and statistical approaches. The research examines the effects of Washingtonia filifera leaf powder, trunk fibres, and biochar derived from the rachis (pyrolyzed at 400 degrees C) on the properties of reinforced soil. Factors investigated include additive percentage (1%, 3%, 5%), sodium hydroxide (NaOH) solution concentration (2%, 5%, 8%), and immersion time (1 h, 4 h, 7 h). A Box-Behnken experimental design with 15 trials was employed to prepare soil-powder, soil-fiber, and soil-biochar composites. Direct shear tests were conducted on reinforced and unreinforced specimens to determine shear strength, cohesion, and friction angle. Results showed significant improvement in shear strength for all additives under normal stresses of 100, 200, and 300 kPa. Increasing additive content enhanced both cohesion and friction angle. Biochar-reinforced soil yielded the highest cohesion of 112 kPa, followed by fiber-soil with 70 kPa and powder-soil with 69 kPa, compared to 15 kPa in unreinforced soil. Additionally, soil mixed with powder, fiber, and biochar exhibited friction angle improvements of 57%, 93%, and 110% respectively, from an initial 13.5 degrees in unreinforced soil. Regression models were developed for shear stress responses using the Response Surface Methodology, and the influence of each parameter on the models was determined using ANOVA analysis. Using a combined approach of response surface methodology (RSM) and the desirability function, optimal values (5% of additives, 5% NaOH concentration, and 1 h of immersion time) were determined. These optimal values agreed well with the experimental results. It can be concluded that the inclusion of the three additives has positive benefits on the mechanical properties of the reinforced soil, with biochar demonstrating the most significant improvements.

A renewed interest in Moon exploration has been forming in recent years due to its close proximity as well as identification of key resources such as water ice in Lunar polar regions. Furthermore, the launch industry has been transforming with increased availability in the variety and instance of spacecraft launchers. Additionally, rideshare missions are becoming the new norm. Rideshare missions not only to LEO but even to Geosynchronous Transfer Orbit are currently available, reducing the cost of access to the deep space. Electric propulsion is also becoming more widespread. Advances in these varied fields will possibly converge in capable small spacecraft designs that will be able to carry out complex missions in deep space. This particular study focuses on identifying key sizing parameters of such a spacecraft. An initial trajectory design utilizing AGI's Systems Tool Kit (STK) was carried out involving low-thrust orbit raising from Geosynchronous Transfer Orbit with eventual Lunar capture. Preliminary lunar station keeping was examined. Later, key design parameters such as eclipse times, communication durations etc. were investigated. Overall, a broad framework was obtained upon which optimization studies and preliminary design can be conducted.