Study of the Effects of Projectile Shape in the Asteroid Orbit Change by Spacecraft Impact

Statistical Significance of Mission Parameters on the Deflection Efficiency of Kinetic Impacts: Applications for the Next-generation Kinetic Impactor

“…Note, however, that more realistic target properties should be studied to fully understand these effects. Previous experimental kinetic impact studies (Ikeda et al 2017) have suggested that the impactor geometry may influence the ejecta velocity distribution. We do not see strong statistical evidence that supports this; however, as discussed in Section 3.1.2, Figure 8 showed some evidence of geometry effects occurring in the normalized ejecta massvelocity distributions for the impactors with impact velocities of 500 m s −1 .…”

“…This paper investigates six different impactor geometries: sphere, plate, ring, ogive, cone with a solid nose, and cone with a hollow nose (Figure 2). The morphology (shape) and composition (Al or Cu) of the impactors were motivated by experimental findings from previous works (Ikeda et al 2017), munitions ballistics studies (Harvey 1948;Stefanopoulos et al 2014), and realistic impactor spacecraft end-members (A' Hearn et al 2005;Schultz et al 2010;Cheng et al 2018). The simple impactor shapes (sphere, plate, and ring) were modeled using 2D AMR grids, which are less computationally expensive compared to their 3D counterparts.…”

“…The extent to which β can be optimized remains an open question because it depends on asteroid parameters that can have rather high uncertainties, such as the local topography at the impact site and target material properties like cohesion and porosity (Stickle et al 2015;Cheng et al 2016;Raducan et al 2019). Previous experimental and computational work has shown that β depends on the impact velocity (Holsapple & Housen 2012), target material properties (i.e., strength, porosity, cohesion, and internal friction; Tedeschi et al 1995;Holsapple & Housen 2012;Walker et al 2013;Bruck Syal et al 2016;Raducan et al 2019;Rainey et al 2020;Walker et al 2020), and impactor properties (Ikeda et al 2017). While it is impossible to control the composition or morphology of a real asteroid (though such properties could be constrained by a reconnaissance mission, if time allowed), there is opportunity to tailor the design of the impactor.…”

“…Previous studies on the effect of impactor shape on momentum enhancement are quite sparse. Ikeda et al (2017) presented results from a two-stage light gun that launched five different aluminum impactor geometries into a firebrick target (density = 2.0 g cm −3 ) mounted on a ballistic pendulum to measure β. Figure 1 replots a subset of their findings in addition to lines representing a linear fit (ax + b) to the data, which captures the general trends.…”

Spacecraft Geometry Effects on Kinetic Impactor Missions

“…There have been some investigations of the effect of projectile geometry. Ikeda et al (2017) performed a series of gas gun experiments with projectiles with different simple shapes (cylinders, spheres, cones, and cups). Of particular relevance to our study, Ikeda et al (2017) note a complex trend in the resulting ejecta momentum based on projectile type and impact velocity: hollow shapes produce larger ejecta momenta for small impact velocities, while a solid sphere impactor fares best at high impact velocities.…”