# # Program information file # PROGRAM_ID 2021A003 PROGRAM_TITLE Investigation of the Massalia asteroid family as the source of L-chondrites PROGRAM_INV1 Michael Gaffey PROGRAM_INV2 Sherry Fieber-Beyer PROGRAM_INV3 Justin Germann PROGRAM_INV4 Caleb Strom PROGRAM_INV5 PROGRAM_SCICAT solar system PROGRAM_ABSTRACT_BEG Asteroids and their natural samples, the meteorites, provide direct information on the thermal and chemical states of the late solar nebula and the early solar system. They also provide evidence on the collisional and orbital evolution of the population of these minor planets over the past 4.5 billion years as well as the sources of the current near-Earth asteroid population, which represent both a risk [impact hazard] and opportunity [resources] for humanity. Of particular interest are the L-chondrites, the most abundant type among meteorite falls [~38% of falls]. Based on meteorite evidence, the L-chondrite parent body suffered a catastrophic collision ~470 Myr ago, which apparently disrupted the body forming an asteroid family [a group of fragments following similar orbits]. This event is recorded in Middle and Late Ordovician marine sediments by a high abundance of fossil L-chondrites [~100 times background fall rates], and a correspondingly high terrestrial cratering rate. Recent work had linked abundant L-chondrite dust in Ordovician sediments to the mid-Ordovician ice age due to reduced sunlight due to dust from the breakup. We propose SpeX observation to obtaining VNIR [~0.7 -- 2.5 um] reflectance spectra of a representative sample of the Massalia asteroid family, currently the best L-chondrite source candidate. Confirming it as the L-chondrite source would further several major advances. First, it would establish the early solar system spatial context for the chemical, thermal and temporal conditions recorded in the L-chondrites. Second, it would provide a firm age on a family forming event, helping to calibrate theoretical models of orbital diffusion and evolution of the asteroid population and of the delivery of asteroids into the near-Earth population. And if the Massalia family can be confirmed as the source of L-chondrites, it would strengthen the link between a cosmic event and significant terrestrial consequence. PROGRAM_ABSTRACT_END