RUI: Using Lunar Impact Glasses as Tools for Investigating Solar System Processes

Albion College, Albion MI

Investigators

Abstract

The appearance of abundant craters on the Moon makes it clear that objects from the outer Solar System have bombarded objects in the inner Solar System over time. Bombardment by large objects may have had fundamental effects on our Earth, including possibly bringing the molecules that are necessary for life. On Earth, it is rare to see the evidence of these impacts because of the constant changes to its surface due to geological (e.g. earthquakes and volcanic eruptions) and meteorological (e.g. wind and rain) processes. However, the Moon, due to its nearness to Earth, serves as a good substitute for understanding terrestrial impact events. But the timing of impacts on the Moon over the last 4500 million years is not well understood. This study will examine samples of lunar material affected by the bombardment that were brought back by the Apollo missions to try and determine how when they were formed and what they are made of. This will help us determine what kinds of objects hit the earth, and when, potentially providing insights into their influence on Earth's evolution. The PI resides at a predominantly undergraduate college, and will involve her students in studying the samples and their data so that they will learn how to manage and think critically about large data sets. She will also bring students to the annual Lunar and Planetary Science Conference to present their results. Thus, they will develop skills that will benefit them in graduate school or the workforce, and their involvement in inquiry-based learning in science, technology, engineering and mathematics (STEM) fields achieves a key aspect of the National Science Foundation's mission. Furthermore, students who work with the lunar samples and their data will become knowledgeable about extraterrestrial sample characterization and may be poised to be some of the best-prepared graduate students available to work on any samples returned from both the Moon and Mars in the next ~20 years. The Moon provides the most clear and complete history of impact events in the inner Solar System. Bombarded since its formation ~4.5 billion years ago, the Moon's impact record can be used to gain insights into how the Earth has been influenced by similar impacting events over billions of years. The timing of impacts on the Moon, however, is not well understood and has been the focus of many studies. Deciphering the lunar impact history is a complex process and lunar impact glasses, numerous in the regolith samples returned with the Apollo missions, can be used to address this issue. This study focuses on obtaining geochemical and geochronological data on lunar impact glasses, which are pieces of melted regolith (lunar dirt) created by energetic impacting events on the Moon. These impact glasses possess the composition of the target material and can be dated by the 40Ar/39Ar (argon) method in order to determine their age of formation, how long they have been exposed at the lunar surface, and the composition of the solar wind prior to the time of burial. The study's objective is to understand the ages of impact glasses, along with their compositions, in order to learn more about Solar System processes. In particular, team can begin to piece together information about the rate of impact events and their effects (if any) on Earth, as well as the changing nature (if any) of the solar wind composition.