Surface Timeline Management and Analysis for the Mars Sample Return Mission

The Mars Sample Return Campaign being planned jointly by the U.S. National Aeronautics and Space Administration and the European Space Agency seeks to return samples of Martian rocks and atmosphere from the surface of Mars to Earth for subsequent scientific analysis. It is comprised of two flight projects, which would retrieve the samples acquired by NASA's Mars 2020 Perseverance rover and return them to Earth. One of the flight projects would be the Sample Retrieval Lander, led by NASA, which would land on the surface of Mars, collect the samples from Mars 2020, and launch them into Mars orbit. The second flight project, led by the European Space Agency, would be the Earth Return Orbiter, which would capture the samples and return them to Earth.The baseline Sample Retrieval Lander surface mission nominally extends from landing on October 17, 2030 to the end of the Mars launch period on May 27, 2031, which yields a total surface mission duration of 222 Earth days, or 215 Mars Sols. In the most constrained timeline, the Sample Retrieval Lander could land as late as November 11, 2030, reducing the total surface mission duration to 197 Earth days, or 190 Mars sols. The limited time to perform the Sample Retrieval Lander surface mission is a critical constraint on the surface phase and drives many aspects of flight system and mission system design. Unlike previous Mars missions, there is no possibility of extended mission time on the surface, due to the Earth return launch constraint. It is therefore imperative to manage the Sample Retrieval Lander surface timeline as a critical project resource.This paper will present an overview of management practices and analytical methodologies developed by the Sample Retrieval Lander surface team to ensure mission objectives are met within the available surface mission timeline. The nominal surface timeline is built from the bottom up, starting with the basic duration constrained by activity duration, energy consumption, and ground in the loop decisions. Growth factors and developmental margin are added to the basic duration to yield the maximum growth timeline duration. This maximum growth timeline duration plus the desired operational margin is compared against the available mission duration of 190 sols to assess the health of the surface timeline. A suite of products has been developed to capture the robustness of the surface timeline, conduct probabilistic analysis of the timeline, and provide regular reporting on the health of the timeline with data visualizations to inform technical and operational design decisions. The timeline analysis and management practices outlined in this paper aim to serve as a resource for future time- constrained aerospace missions and applications.The decision to implement Mars Sample Return will not be finalized until NASA's completion of the National Environmental Policy Act (NEPA) process. This document is being made available for information purposes only.