Six Years and 184 Tickets: The Vast Scope of the Mars Science Laboratory's Ultimate Flight Software Release

The Mars Science Laboratory (MSL) Curiosity rover is about to receive its sixth and likely final complete flight software update after having operated on Mars for more than a decade. Software transitions on MSL provide an opportunity to add or replace functionality, fix bugs, and prepare for future capabilities. The penultimate full software release, R12, was installed on Curiosity in 2015, three years after its August 2012 landing, and was followed over the subsequent seven years by many patches as engineers worked to address new mission constraints quickly. Because each additional patch increases the complexity of maintaining and operating the rover, a new flight software update called R13 was proposed, which aimed to make operations more straightforward by incorporating existing patches, improved software capabilities, and new software capabilities into a single monolithic rover flight software image. The R13 development effort kicked off in early 2017. Over the next six years, the scope of R13 expanded to include many desired capabilities and bug fixes - some of which were proposed even earlier than 2015 but were unable to be implemented in R12. Overall, the MSL Change Control Board approved 56 bug fixes and 53 new features for R13 development. Twenty-seven developers implemented these changes over a 3.5-year period. Following a 2.25-year testing campaign, R13 was approved for use in flight onboard Curiosity. In this paper, we detail the path of the R13 flight software release from its proposal in April 2016 to its approval for use in flight in September 2022.