Enabling Parallel Activities for Mars 2020 Rover Surface Operations

Abstract

Level 1 requirements levied on the Mars 2020 mission from NASA Headquarters challenged the Mars 2020 surface mission (also known as the Perseverance rover) to perform significantly better relative to the 2012 Mars Science Lab (MSL) surface mission (also known as the Curiosity rover). In one and a quarter Mars years, the Perseverance rover was expected to drive 50 percent farther and collect over twice as many samples as its predecessor, Curiosity. In order to reach these requirements, Mars 2020 came up with five guiding principles, two of which were “Be fast, be flexible: perform flight and ground functions more quickly” and “Do more science: increase the time that the vehicle is actively pursuing science on Mars”. These guiding principles required the mission to lay the groundwork early on for more surface activities to be performed in parallel, such as thinking while driving. Parallelism enabled both direct efficiency gains, such as completing multiple activities simultaneously during a given time frame, and indirect gains, such as increased available energy and better informed tactical planning due to more data being available sooner. These efficiency gains allowed the rover to complete more complex plans and better handle adversity such as data return disruptions. Although the mission planned to test and approve most of the parallel activities in the development phase, limitations on budget, time and personnel drove the majority of parallel activity testing and approvals to occur in the operations phase. Ideally, any activity can run concurrently with any other activity, but constraints such as Electromagnetic Interference (EMI), hardware safety, and resource utilization prevent some activities from running in parallel. In order to coordinate these behaviors on the rover, the mission needed an efficient and streamlined mechanism to manage them on the ground and maximize the amount of time the rover could pursue science on Mars. In response to this challenge, the Mars 2020 Surface Operations Team overhauled a legacy product from MSL called the Parallelism Matrix. Over the course of the primary mission, the Mars 2020 Parallelism Team made the following improvements: established a process to triage untested activity parallelism, enabled automatic updates to the matrix after downlinked data was analyzed, created a thorough testing campaign to investigate and approve untested parallel interactions, and provided a tool to autonomously track executed parallel activities as soon as data hit the ground. This paper will discuss: similarities and differences between the Perseverance and Curiosity missions with respect to maximizing science exploration time, Mars 2020's new Flight Software (FSW) capabilities that enabled more parallelism, the Surface EMI testing campaign, the Surface Operations Parallelism Working Group efforts, Surface Operations parallelism tools and processes, the current state of parallel activity efforts on Mars 2020, the measurable benefits and achievements of parallelism, and the lessons learned and recommendations for the future.