Chronos Program: Unraveling The Bombardment History Of The Inner Solar System

Mark Robinson
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Chronos Program: Unraveling The Bombardment History Of The Inner Solar System
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What is the history of bombardment of the inner Solar System? Was there a cataclysm event? What happened post heavy-bombardment? The answers to these fundamental questions literally rest on surface the Moon, just waiting to be scooped up. First, determining the correct relative and absolute ages of lunar basins will tell us if there was a terminal cataclysm at the end of heavy bombardment (~3.9 by). The so-called Nice model appeared as a result of the idea of a spike, or cataclysm, at the end of the period of heavy bombardment, which came out of Apollo era relative and absolute dating of lunar basins. The whole idea of such a cataclysm is now being re-evaluated and it seems equally likely that there was no cataclysm, and thus the Nice model may be irrelevant. Settling this question will likely be the number one priority of the next planetary science decadal plan. CSFD based absolute age dating of all other inner Solar System bodies assumes we correctly understand the lunar cratering chronology. Final accretion and migration of the outer planets assumes we correctly understand the lunar cratering chronology. Understanding lunar bombardment history is not a lunar question, but rather a Solar System question. Of course the period after 3.9 by until today is also important and our absolute knowledge of key events is sketchy at best. The chronology of the Bombardment History of the Inner Solar System can be determined by sampling ten sites on the Moon, thus I propose the Chronos Program be seriously considered as the future of human exploration of the Moon is planned. Rationale: Determine the timing of key events on the Moon by developing a sustainable sample return program with future relevance to Mars Sample Return. Need: Understand impactor history within the Solar System and the geochemical evolution of the Moon. Goals: Primary – Determine the age of formation of key landforms on the Moon over a ~4 billion year period. Secondary – Determine the geochemical evolution of the Moon over time. Objectives: Develop a cost effective robotic system to collect and bring samples from multiple locations on the Moon and enable Earth return. 1) land safely and accurately within ± 200 m of assigned target 2) collect and document appropriate sample for radiometric age dating 3) store sample in sealed container 4) return sample to Earth in pristine state The Chronos Program goals and objectives require documented sample return from ten widely separated sites, clearly an ambitious program. The thought of sustaining a ten sample return program, at first blush, may seem staggering. However it may be possible and plausible by leveraging other orbital assets to shift the return to Earth costs (from lunar orbit) to an existing infrastructure, and reusing the land-and-return vehicle. The Chronos architecture is based on a simple vehicle capable of descending from lunar orbit, landing precisely, collecting a documented sample, and returning to an orbital asset. After the sample is transferred to the orbiter the Chronos vehicle is refueled and sent down to the surface to sample a different area. This procedure is repeated until all the ten sites are adequately sampled. Engineering Feed Forward Benefits: Test and perfect autonomous precision landing and hazard avoidance applicable to future landed vehicles (robotic and crewed), perfect sampling and sealing operations and technology, perfect automated rendezvous and capture by human tended vehicle, perfect in space refueling and reuse of land-and-return vehicle. A single Mars sample return mission is estimated to cost between $5 and $20 billion, mitigating risks through the Chronos Program represents systems engineering best practices.