Earth Impact Studies for Mars Sample Return

Dynamic finite element modeling of a series of penetrometer drop tests into soft clay that were conducted as part of the Mars sample return advanced technology program is discussed. Structural impacts into soil continue to challenge analysts to develop accurate soil material models for finite element simulations to predict the observed deceleration pulse and impact crater. Parametric studies are presented for penetrometers of varying diameter, mass, and impact velocity to a maximum of 45 m/s, which is the expected terminal velocity of a sample return capsule. Parameters influencing the simulation such as the contact penalty factor and the material model representing the soil are discussed. An empirical relationship between peak deceleration and key parameters is developed and is shown to correlate experimental and analytical results. The results provide preliminary design guidelines for Earth impact that may be useful for future space exploration sample return missions.