Dismantling the oblique granular impact; Towards better landings on planets, moons, and asteroids
Peter Miklavcic, PhD Qualifying Exam, Advised by Professor Hesam Askari
Thursday, February 24, 2022
Oblique, low-velocity impacts of man-made spacecraft onto extraterrestrial granular terrains are an inevitability in space exploration. This poses a challenge as such granular media, often called 'regolith', differs from Earthen materials in terms of grain roughness and grain size distribution. Within a sample of regolith, grain geometries are found to be rough and vesicular and grain sizes may vary by an order of magnitude or more. Such features are driven by the absence of erosive forces in extraterrestrial environments that homogenize and smooth grains here on Earth. The granular mechanics in extraterrestrial surfaces are also heavily influenced by reduced-gravity environments. The objectives of this proposed work will explore how low-velocity angled impact behaviors are affected by these environmental factors - acceleration of gravity, grain size distribution - and dynamic factors - projectile velocity and approach angle. Simulations will be conducted in Earth-like gravity and asteroid Bennu-like micro-gravity and both mono-disperse and bi-disperse granular systems will be studied. Discrete granular simulations will afford study of sub-surface behavior of granular media during an impact in terms of packing fraction, strain, and force chain networks. Successful completion of all objectives will add to the collective understanding of the extra-terrestrial oblique, low-velocity impact event. This result has implications throughout space-faring industries, providing a means to improve mission outcomes by boosting the likelihood of a successful landing event.