Deciphering the origin and evolution of planets, moons, and small bodies is one of the grand challenges of planetary science. In order to meet this challenge, the processes that shape solar system objects must be understood in detail. Impact cratering is one such process. Impact craters scar the surfaces of nearly every solid body in the Solar System. However, impacts can do more than sculpt: they also can be a force for compositional change. Meteorites, spacecraft data, experiments, and numerical models all indicate that portions of the projectile can survive impact and be retained on planetary surfaces, particularly at speeds common in the asteroid and Kuiper belts. Such findings raise questions: What conditions are required for impact delivery? How do variables such as speed, angle, impactor properties, and target properties affect delivery? What does the impactor contribution look like: that is, what is its physical state? To find answers, I draw on hypervelocity impact experiments and terrestrial impact craters. I employ a variety of chemical, spectroscopic, and isotopic analyses. Chapter one examines whether Ceres, the largest object in the asteroid belt, could have accumulated a significant impactor component. Chapter two assesses the effects of impact variables on projectile preservation. Chapter three investigates whether impact melts from Canada’s West Clearwater crater carry a meteoritic signature. And, chapter four investigates how efficiently impacts deliver water. Each chapter reaches its own conclusions, but the findings highlight three common themes. First, impact delivery should be the expectation, not the exception, in the asteroid and Kuiper belts, among the Jupiter Trojans, and during lower velocity (<6 km s-1) impacts at the Moon and Mars. Second, impact angle profoundly affects the amount of material delivered by impact, the distribution of impactor material, and the physical state of the impactor component. Third, because exogenic contamination should be commonplace, missions such as OSIRIS-REx, Hayabusa-2, Psyche, and Lucy must plan how to recognize the exogenic material that these missions will likely encounter. Rather than tainting the targets of these missions, exogenic debris should reveal valuable insights into the solar system’s origin and evolution, insights unavailable on Earth.
Asteroids--Collisions with Earth
United States. National Aeronautics and Space Administration
Daly, Ronald Terik,
"Preserving Projectiles During Impacts on Asteroids and Planets"
Earth, Environmental and Planetary Sciences Theses and Dissertations.
Brown Digital Repository. Brown University Library.